




















                                EZNEC Version 2.0







                      Copyright (c) 1997 by Roy W. Lewallen




                                     CONTENTS


        INTRODUCTION  . . . . . . . . . . . . . . . . . . . . . . . . .  5
             ACKNOWLEDGEMENTS . . . . . . . . . . . . . . . . . . . . .  6
             A FEW WORDS ABOUT COPY PROTECTION  . . . . . . . . . . . .  6
             COPYRIGHT NOTICE . . . . . . . . . . . . . . . . . . . . .  7
             A FEW WORDS ABOUT LEGALESE . . . . . . . . . . . . . . . .  7
             SINGLE USE SOFTWARE LICENSE AGREEMENT  . . . . . . . . . .  7
             DISCLAIMER . . . . . . . . . . . . . . . . . . . . . . . .  9
             ABOUT THIS MANUAL  . . . . . . . . . . . . . . . . . . . . 10
             DESCRIPTION  . . . . . . . . . . . . . . . . . . . . . . . 10
             EZNEC AND NEC  . . . . . . . . . . . . . . . . . . . . . . 12
             HARDWARE REQUIREMENTS  . . . . . . . . . . . . . . . . . . 13
             INCOMPATIBILITIES  . . . . . . . . . . . . . . . . . . . . 13

        GETTING  STARTED  . . . . . . . . . . . . . . . . . . . . . . . 14
             INSTALLATION . . . . . . . . . . . . . . . . . . . . . . . 15
                  Running INSTALL . . . . . . . . . . . . . . . . . . . 15
                  Windows 3.xx EZNEC Installation . . . . . . . . . . . 16
                  Windows 95 EZNEC Installation . . . . . . . . . . . . 16
                  Windows NT EZNEC Installation . . . . . . . . . . . . 19
                    . . . . . . . . . . . . . . . . . . . . . . . . . . 20
             RUNNING EZSETUP  . . . . . . . . . . . . . . . . . . . . . 20
             MEMORY CONSIDERATIONS AND COMPUTER SETUP . . . . . . . . . 24
             MEMORY MANAGER SETUP . . . . . . . . . . . . . . . . . . . 25
             RUNNING EZNEC UNDER WINDOWS  . . . . . . . . . . . . . . . 26
                  Inserting EZNEC Graphics in Windows Documents . . . . 26

        UPGRADING FROM EZNEC V. 1 . . . . . . . . . . . . . . . . . . . 27
             DIFFERENCES FROM EZNEC V. 1  . . . . . . . . . . . . . . . 28
             USING ELNEC and EZNEC v. 1 FILES WITH EZNEC v. 2 . . . . . 29
             UPGRADING  . . . . . . . . . . . . . . . . . . . . . . . . 29

        RUNNING EZNEC . . . . . . . . . . . . . . . . . . . . . . . . . 30
             STARTING EZNEC . . . . . . . . . . . . . . . . . . . . . . 31
             STARTING EZNEC IN TRACEVIEW MODE . . . . . . . . . . . . . 31
             WHAT TO WATCH FOR WHILE EZNEC IS RUNNING . . . . . . . . . 31
             TEST DRIVE . . . . . . . . . . . . . . . . . . . . . . . . 31
                  Along the Straightaway  . . . . . . . . . . . . . . . 32
                  Through the Curves  . . . . . . . . . . . . . . . . . 35
                  On The Race Course  . . . . . . . . . . . . . . . . . 40
             WHAT'S HAPPENING . . . . . . . . . . . . . . . . . . . . . 43

        MODELING WITH EZNEC . . . . . . . . . . . . . . . . . . . . . . 44
             INTRODUCTION TO MODELING . . . . . . . . . . . . . . . . . 45
             MODELING THE ANTENNA STRUCTURE . . . . . . . . . . . . . . 45
             CONSIDERATIONS FOR MODELING WIRES  . . . . . . . . . . . . 47
                  General . . . . . . . . . . . . . . . . . . . . . . . 47
                  "Crossed Dipoles" . . . . . . . . . . . . . . . . . . 48


                                        2




                  Closely Spaced Wires  . . . . . . . . . . . . . . . . 48
                  Elevated Radial Systems . . . . . . . . . . . . . . . 48
                  Feedlines and Baluns  . . . . . . . . . . . . . . . . 49
                  Linear Loaded Antennas  . . . . . . . . . . . . . . . 50
                  Log Periodic Antennas . . . . . . . . . . . . . . . . 50
                  Multiband Antennas  . . . . . . . . . . . . . . . . . 50
                  Shunt Fed Towers  . . . . . . . . . . . . . . . . . . 51
                  Small Loops . . . . . . . . . . . . . . . . . . . . . 51
                  Wires With Different Diameters ("Stepped Diameter")
                    . . . . . . . . . . . . . . . . . . . . . . . . . . 51
                  Wires Joining at an Acute Angle . . . . . . . . . . . 53
             MODELING GROUND  . . . . . . . . . . . . . . . . . . . . . 54
                  Ground Model Types  . . . . . . . . . . . . . . . . . 54
                  Connection to Ground  . . . . . . . . . . . . . . . . 55
                  Buried Wires  . . . . . . . . . . . . . . . . . . . . 55
                  Using Two Media . . . . . . . . . . . . . . . . . . . 55
                  Real Ground Limitations . . . . . . . . . . . . . . . 55
             USING LOADS  . . . . . . . . . . . . . . . . . . . . . . . 56
             USING SOURCES  . . . . . . . . . . . . . . . . . . . . . . 57
                  Phased Arrays . . . . . . . . . . . . . . . . . . . . 58
                  Using Multiple Sources  . . . . . . . . . . . . . . . 59
             USING TRANSMISSION LINES . . . . . . . . . . . . . . . . . 59
             NEAR FIELD / FAR FIELD ANALYSIS  . . . . . . . . . . . . . 61
             INTERPRETING THE RESULTS . . . . . . . . . . . . . . . . . 63
                  Patterns  . . . . . . . . . . . . . . . . . . . . . . 63
                  Near Field  . . . . . . . . . . . . . . . . . . . . . 63
                  Source (Feedpoint) Impedance and SWR  . . . . . . . . 64
                  Currents  . . . . . . . . . . . . . . . . . . . . . . 65
                  Load Data . . . . . . . . . . . . . . . . . . . . . . 66
             TIPS . . . . . . . . . . . . . . . . . . . . . . . . . . . 66
                  Doubling the Number of Available Segments . . . . . . 66
                  Segment Length Tapering . . . . . . . . . . . . . . . 67
                  Scaling . . . . . . . . . . . . . . . . . . . . . . . 67
                  Conductivity and Scaling  . . . . . . . . . . . . . . 68
                  Using Templates . . . . . . . . . . . . . . . . . . . 68
                  Modeling Complex Structures . . . . . . . . . . . . . 68
             WHY NOT DBD? . . . . . . . . . . . . . . . . . . . . . . . 69

        REFERENCE MANUAL  . . . . . . . . . . . . . . . . . . . . . . . 70
             GENERAL INFORMATION AND CONVENTIONS  . . . . . . . . . . . 71
             SCROLLING  . . . . . . . . . . . . . . . . . . . . . . . . 73
             LIMITATIONS  . . . . . . . . . . . . . . . . . . . . . . . 73
             THE MENUS  . . . . . . . . . . . . . . . . . . . . . . . . 74
                  The Main Menu . . . . . . . . . . . . . . . . . . . . 74
                  The Options Menu  . . . . . . . . . . . . . . . . . . 82
                  The Wires Menu  . . . . . . . . . . . . . . . . . . . 85
                  The Sources Menu  . . . . . . . . . . . . . . . . . . 94
                  The Loads Menu  . . . . . . . . . . . . . . . . . . . 96
                  The Transmission Lines Menu . . . . . . . . . . . . . 97
                  The Media Menu  . . . . . . . . . . . . . . . . . . . 99


                                        3




                  The 2D Pattern Plot Display and Menu  . . . . . . .  101
                  The 3D Pattern Plot Display and Menu  . . . . . . .  104
                  The View Antenna Display and Menu . . . . . . . . .  106
                  The SWR Graph Display and Menu  . . . . . . . . . .  114
                  The Near Field Setup Menu . . . . . . . . . . . . .  115
                  Frequency Sweep and the Frequency Sweep Menu  . . .  116
             GROUP EDIT . . . . . . . . . . . . . . . . . . . . . . .  120
             SAVING, RECALLING, AND DELETING FILES  . . . . . . . . .  123
             SAVING, RECALLING, COMBINING, AND DELETING ANTENNA
             DESCRIPTIONS . . . . . . . . . . . . . . . . . . . . . .  123
             USING THE NEC BURIED GROUND RADIAL MODEL . . . . . . . .  124
                  Adding or Changing Radials in the NEC buried radial
                  model . . . . . . . . . . . . . . . . . . . . . . .  125
             TRACEVIEW  . . . . . . . . . . . . . . . . . . . . . . .  126
                  Starting TraceView  . . . . . . . . . . . . . . . .  126
                  Changing the Primary Trace  . . . . . . . . . . . .  126
                  Ending TraceView  . . . . . . . . . . . . . . . . .  127
             EZNEC FILES  . . . . . . . . . . . . . . . . . . . . . .  127
                  Files on the Distribution Disk(s) . . . . . . . . .  127
                  Files Created by EZNEC and/or EZSETUP . . . . . . .  128
             MICROSMITH . . . . . . . . . . . . . . . . . . . . . . .  130
             PRINTERS . . . . . . . . . . . . . . . . . . . . . . . .  130
             OpenPF PLOT FILE STANDARD  . . . . . . . . . . . . . . .  131
             IMPORTING WIRE DESCRIPTIONS  . . . . . . . . . . . . . .  132
                  Complete Rules for Wire Files Used for Importing  .  133
             THE FREQUENCY LIST FILE  . . . . . . . . . . . . . . . .  135
                  Complete Rules for the Frequency List File  . . . .  135
             PLOTTERS . . . . . . . . . . . . . . . . . . . . . . . .  136
             ENVIRONMENT VARIABLES  . . . . . . . . . . . . . . . . .  136
                  EZNEC environment variables . . . . . . . . . . . .  136
             PROBLEMS . . . . . . . . . . . . . . . . . . . . . . . .  138
             ERROR MESSAGES . . . . . . . . . . . . . . . . . . . . .  143
             HELP!  . . . . . . . . . . . . . . . . . . . . . . . . .  149
             INDEX  . . . . . . . . . . . . . . . . . . . . . . . . .  150


















                                        4


























                                      EZNEC








                                   INTRODUCTION




                                 ACKNOWLEDGEMENTS

        The fundamental computation portion of this program is that of
        NEC-2. Many people have contributed to the development of this
        code, but in recent years the major contributors have been G.J.
        Burke and A.J. Poggio of Lawrence Livermore National Laboratory.
        Without their monumental effort this program would not be
        possible.

        EZNEC has been extensively tested and improved over its
        development cycle. The people who have done this testing (of
        EZNEC and its predecessor ELNEC and professional version EZNEC
        PRO) and by their suggestions and comments made many
        contributions to EZNEC's usability are: Dick Adler, K3CXZ; Jack
        Belrose, VE2CV; Gary Breed, K9AY; Jim Bromley, W5GYJ; John
        Brosnahan, W0UN; Paul Carr, N4PC; L.B. Cebik, W4RNL; Al
        Christman, K3LC; Bill Clarke, WA4BLC; Tony DeBiasi, K2SG; Ed
        Farmer, AA6ZM; Dick Gardner, N1AYW; Ernie Guerri, W6MGI; Linley
        Gumm, K7HFD; Jerry Hall, K1TD; Ed Hanlon; Bob Haviland, W4MB; Wes
        Hayward, W7ZOI; Dick Kiefer, K0DK; Doug McGarrett, WA2SAY; Bob
        Rullman, K7MSH; Jim Sanford, WB4GCS; Roger Steyaert, K7RXV; C.H.
        "Buck" Walter; and Dean Straw, N6BV.

        I want to give special thanks to L.B. Cebik, W4RNL, who made many
        extensive and thorough tests, and numerous thoughtful suggestions
        for several program versions.

        Thanks to all the EZNEC users who took the time to send in their
        suggestions. Finally, but foremost, thanks to my family for being
        understanding and supportive during the many, many hours I've
        spent away from them working on this program.


                        A FEW WORDS ABOUT COPY PROTECTION

        A friend of mine made the observation that a conscience is kind
        of like a little wheel with sharp teeth that spins and digs into
        you. But each time it does, he said, the teeth wear down a little
        so the next time it's not quite as sharp. Eventually, if you use
        it enough, there aren't any teeth left. If the teeth on your
        wheel are worn all the way down, what I'm about to say won't
        reach you anyway so you may as well skip the rest of this
        section.

        Copy protection is a big nuisance to both the user and the
        software developer. It also can necessitate an increase in price.
        That's a lousy deal -- more nuisance for a higher price. That's
        why this software is not copy protected. Yet copying it is easier
        than ripping off a Walkman from K-Mart, with zero chance of
        getting caught (although it's just as illegal and dishonest). So


                                        6




        it's pretty risky to put the product out without copy protection.
        I'm well aware that sellers of similar programs have had to copy-
        protect their programs to prevent such theft. Theft? You bet!
        Literally hundreds of hours (many weeks of full-time work) have
        gone into developing this program and refining it to make it
        useful and easy for you to use. (Other expenses, like
        advertising, aren't cheap either!) So please, when someone asks
        you for a copy of the program, realize that he or she is asking
        you to steal. Politely say no, but give them the name and address
        where they can order a copy. It's a bargain at the price, it'll
        save future users more nuisance and a higher price, and it'll
        save the wear on your conscience wheel. Thanks.


                                 COPYRIGHT NOTICE

        EZNEC Version 2 and its manual are copyright (c) 1997 by Roy W.
        Lewallen. All rights are reserved.


                            A FEW WORDS ABOUT LEGALESE

        I'm no fan of legalese, and this manual contains a good deal more
        than previous versions. But several things have prompted its
        inclusion.  Please carefully read the SINGLE USE SOFTWARE LICENSE
        AGREEMENT and DISCLAIMER below. If you don't accept the
        conditions stated there, you can return the program for a prompt
        and full refund.


                      SINGLE USE SOFTWARE LICENSE AGREEMENT

        By using the software, the user agrees to the following terms and
        conditions.

        Ownership. All ownership of this software is reserved to Roy W.
        Lewallen ("Licensor"). No title to or ownership of any software
        or any parts thereof is transferred by any delivery of this
        software. The use of the software enclosed with this License
        Agreement conclusively establishes Licensee's agreement with all
        the terms and conditions hereof.











                                        7




        Limitation of Liability. Licensor's liability under this
        Agreement shall be limited to a refund of the price paid by
        Licensee for the use of such program. LICENSOR WILL NOT BE LIABLE
        FOR ANY PROPERTY DAMAGE, PERSONAL INJURY, LOSS OF USE,
        INTERRUPTION OF BUSINESS, OR OTHER SPECIAL, INCIDENTAL, OR
        CONSEQUENTIAL DAMAGES, HOWEVER CAUSED, WHETHER FOR BREACH OF
        WARRANTY, CONTRACT, TORT (INCLUDING NEGLIGENCE), STRICT LIABILITY
        OR OTHERWISE.

        Exclusion of Warranties. Licensor excludes all warranties,
        express or implied, including, without limitation, warranty of
        fitness for a particular purpose.

             Licensor's sole warrantee is as follows: At any time, the
             Licensor will refund the full purchase price upon
             notification that the Licensee is not completely satisfied
             with the program. EXCEPT AS STATED IN THE PREVIOUS SENTENCE,
             LICENSOR DOES NOT WARRANT THAT THE FUNCTIONS CONTAINED IN
             THE PROGRAM WILL MEET THE LICENSEE'S REQUIREMENTS. LICENSOR
             MAKES NO OTHER WARRANTIES OF MERCHANTABILITY OR FITNESS FOR
             A PARTICULAR PURPOSE.

        Use of Licensed Software. Licensor is licensing Licensee to use
        the software as a single user. No use of this software may be
        made on a company or location basis including, without
        limitation, local area networks.

        Modification/Copies. Licensee may make copies of the licensed
        program, but no more than one copy per license may be used at any
        one time. Any modification of this licensed software program by
        Licensee shall remain subject to all terms and conditions of this
        Agreement and shall remain the sole property of Licensor; all
        derivative works shall remain the property of Licensor.

        Upgrades. Purchase of a program upgrade at less than the full new
        program price does not confer an additional license, but rather
        upgrades the existing license.

        Protection. During the term of this Agreement, or thereafter, in
        the event Licensee uses or conveys, or attempts to use or convey,
        the licensed program, manual, and/or technical documentation or
        any duplication or modification thereof, in a manner contrary to
        the terms of this Agreement, Licensor shall be entitled to an
        injunction to be issued by any court of equity in joining and
        restraining Licensee from continuing said violation, in addition
        to any damage suffered by Licensor. The provisions of this
        section shall survive any termination of this agreement.





                                        8




        General Terms. The prevailing party in any legal action brought
        under this Agreement shall be entitled to reimbursement for
        reasonable attorney's fees at trial, on appeal and on any
        petition for review.

        Miscellaneous. This instrument contains the entire agreement
        between the parties respecting its subject matter and may only be
        modified in a writing signed by Licensor and Licensee. This
        agreement is governed by the laws of Oregon. Any legal action
        arising out of this Agreement shall be prosecuted in Oregon.
        Licensee submits to the jurisdiction of the courts of Multnomah
        County, Oregon. No waiver by Licensor of any violation or
        nonperformance by Licensee shall be deemed to be a waiver of any
        subsequent violation or nonperformance. All waivers must be in
        writing. In the event any of the provisions of this License
        Agreement are invalid under any applicable statute or rule of
        law, those provisions or portions thereof are to that extent
        deemed to be omitted, or shall be interpreted, if possible, to
        comply with such statute or rule of law.


                                    DISCLAIMER

        The licensee ("Licensee" or "User") acknowledges that the
        reliability of any and all results produced by this software are
        not precise and are subject to significant levels of variability.
        Licensee further acknowledges that the reliability of results can
        be affected by a multitude of factors, including the type of
        antenna used, whether it is used in an urban environment,
        surrounding objects, ground conductivity conditions, and the
        experience and skill of Licensee in using computer modeling
        techniques. Licensee specifically acknowledges that this software
        CANNOT BE USED TO tell User whether (1) the amount of
        electromagnetic energy being emitted from User's antenna is
        unsafe to User, User's family, User's neighbors or anyone else in
        proximity to User's antenna; (2) Licensee's antenna subjects
        Licensee or any other persons to potentially hazardous
        electromagnetic exposure. Licensor, therefore, makes no
        warranties that this software provides any information regarding
        human safety or whether exposure hazardous to humans may result
        from use of Licensee's antenna; Licensee acknowledges he or she
        is not relying on this software to determine whether User's
        antenna is safe or subjects any persons to hazardous or
        potentially hazardous exposures of electromagnetic energy.

        LICENSOR HEREBY DISCLAIMS ANY AND ALL WARRANTIES OF
        MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. LICENSOR'S
        LIABILITY UNDER OR FOR BREACH OF THIS AGREEMENT SHALL BE LIMITED
        TO REFUNDING THE LICENSE FEE PAID BY LICENSEE. IN NO EVENT SHALL
        LICENSOR BE LIABLE FOR SPECIAL, CONSEQUENTIAL, OR INCIDENTAL


                                        9




        DAMAGES, HOWEVER CAUSED, WHETHER FOR BREACH OF WARRANTY,
        NEGLIGENCE, CONTRACT, TORT (INCLUDING STRICT LIABILITY) OR
        OTHERWISE, OR FOR PERSONAL INJURY OR FOR PROPERTY DAMAGE. BY USE
        OF THIS SOFTWARE, LICENSEE HEREBY ACKNOWLEDGES AND AGREES THAT HE
        OR SHE WILL BE SOLELY RESPONSIBLE FOR ANY INJURIES ARISING OUT OF
        OR RELATING TO ELECTROMAGNETIC ENERGY EMITTING FROM USER'S RADIO
        ANTENNA. USER WILL INDEPENDENTLY SATISFY HIMSELF/HERSELF THAT
        USER'S RADIO ANTENNA DOES NOT EXPOSE ANY PERSONS TO HAZARDOUS
        LEVELS OF ELECTROMAGNETIC ENERGY AND DOES NOT SUBJECT ANY PERSONS
        TO UNSAFE CONDITIONS. USER WILL DEFEND, INDEMNIFY, AND HOLD
        LICENSOR HARMLESS FROM ANY AND ALL CLAIMS RELATING TO
        ELECTROMAGNETIC ENERGY EMITTED FROM USER'S ANTENNA INCLUDING,
        WITHOUT LIMITATION, CLAIMS THAT THE LEVEL OF SUCH EMISSIONS IS
        UNSAFE. LICENSEE RELEASES LICENSOR FROM ANY CLAIMS RELATING TO
        THE INABILITY OF THIS SOFTWARE TO DETERMINE WHETHER LEVELS OF
        ELECTROMAGNETIC ENERGY COMING FROM LICENSEE'S ANTENNA ARE
        HAZARDOUS OR UNSAFE TO ANY HUMAN BEINGS.


                                ABOUT THIS MANUAL

        A glance at this manual might give the impression that EZNEC is a
        complex, difficult-to-use program. Despite its power, nothing is
        farther from the truth. In all likelihood, you'll be able to
        begin analyzing antennas with just a few minutes' familiarization
        (Try the TEST DRIVE). But inevitably you'll want to learn all the
        shortcuts and features built into EZNEC, or will have a question
        about the operation or meaning of some function or menu
        selection. This manual is written so you'll have the answers at
        your fingertips, whenever you need them.


                                   DESCRIPTION

        EZNEC is a powerful but easy-to-use program for modeling and
        analyzing antennas. A wide variety of antenna types and parasitic
        structures can be modeled.

        The far-field pattern of an antenna, including gain, can be
        plotted as a three-dimensional (3D) figure, as a two-dimensional
        (2D) azimuth or elevation "slice" on a logarithmic-dB (ARRL type)
        or linear-dB polar plot, or presented in tabular form. All
        outputs, including plots, can be printed on an HP LaserJet or
        DeskJet printer, or Epson-compatible dot-matrix printer. A
        special ANALYZE feature gives the forward gain, front-to-back or
        front-to-side ratio, beamwidth, angles of 3-dB pattern points,
        major sidelobe level, and front-to-sidelobe ratio. The points
        which ANALYZE finds are included on the plot to show its
        determination of these points. In addition, you can display or
        print the voltage, current, impedance, and SWR (for systems of


                                       10




        any characteristic impedance) at each excitation source; the
        voltage, current, impedance, and power loss of each load; and the
        current distribution on each wire. The antenna description and a
        3D representation of the antenna may also be printed. Near field
        data are available in tabular form.

        EZNEC offers an easy, menu-based system for describing and
        modifying the antenna. Many special features are included to make
        modifications fast and simple; for example, wires can be added,
        deleted, or tilted, or wire lengths or antenna height changed,
        with a few keystrokes. Groups of wires can be copied or modified
        to simplify development of complex models.

        Antenna descriptions and patterns are easily saved and recalled
        from disk files, and can be superimposed for direct comparison.

        EZNEC has many other features, just a very few of which are:

             - Three-dimensional pattern display, with direct cursor
             readout of gain in any direction.

             - SWR graph with positionable cursor readout.

             - "Guideline Check" to warn user if several modeling
             guidelines have been exceeded or when parameters are nearing
             limits.

             - Inclusion of true current, as well as voltage, sources.

             - Transmission line models.

             - Inclusion of special source types to permit placing
             sources at wire junctions, normally impossible with NEC-
             based programs.

             - Three-dimensional View Antenna feature to graphically show
             what the antenna looks  like, with currents and pattern
             superimposed if desired.

             - Ability to save patterns and to superimpose several
             patterns on a single grid to compare antennas and see the
             effect of changes.

             - Frequency sweep capability, either uniform steps or user-
             specified frequencies.

             - Automatic or manual wire segmentation.

             - Inclusion of wire loss if desired.



                                       11




             - Many shortcuts for entering the antenna description,
             including tilting wires and changing wire length.

             - Advanced editing features, allowing you to copy, add, or
             delete groups of wires, sources, or loads.

             - 2D Far-field (pattern) analysis and plots/tables can be
             restricted to any range of angles to speed computation when
             only one portion of the pattern is of interest.

             - All choices are made within EZNEC; it's not necessary to
             leave the program to change features or descriptions.
             (Exception: printer type, screen colors, and a few other
             infrequently changed options are defined with a setup
             program.)

             - Ability to handle complex antennas, with up to 500
             segments.

             - Extensive error trapping to prevent "crashes" and to warn
             the user of conditions which may cause inaccuracy.


                                  EZNEC AND NEC

        Although EZNEC uses NEC-2 as a calculating engine, there are
        several significant differences.

        Voltages and currents: NEC-2 uses peak values for voltages and
        currents. EZNEC interprets and reports values in RMS. The power
        reported by EZNEC is the same as that reported by NEC-2.

        Data input and output: Instead of editing an ASCII file,
        descriptions are entered via a spreadsheet-like entry system.
        This allows very easy modification, and the ability to
        immediately see the result on the antenna structure. (Note,
        however, that EZNEC can import wire descriptions from a simple-
        format ASCII file, although its format is different than NEC.)
        EZNEC does not read or write NEC-format files.

        NEC-2 features: Not all NEC-2 features are implemented in EZNEC.
        Those not implemented include symmetry, networks, patches,
        helices, arcs, and catenary wires. EZNEC is chiefly oriented
        toward the analysis of wire antennas.








                                       12




        Angles: EZNEC uses elevation angle in place of zenith angle.
        Elevation angle is measured upward from the horizon (XY plane).
        EZNEC also permits an alternate method of displaying azimuth
        angle. This corresponds to compass bearing, and is measured
        clockwise from the +y axis.

        Power: In NEC, all voltage sources are absolute. EZNEC permits
        you to specify a particular power level. If this is done, all
        voltage and current sources will be adjusted in proportion to
        obtain the specified total power. This is useful for determining,
        for example, voltage stress on or power dissipation of loading
        components under actual operating conditions, or of near field
        strength resulting from a specific power input.


                              HARDWARE REQUIREMENTS

        EZNEC requires a PC-compatible computer with 80386 or higher
        processor; a coprocessor (either separate or built into the CPU);
        at least 3 megabytes of available extended memory; and EGA or VGA
        graphics. Hard disk space requirement varies with the complexity
        of antenna and amount of available RAM. The program itself
        requires only two megabytes of hard disk space, but several
        additional megabytes can be required for temporary storage when
        analyzing complex antennas.

        Text printing can be done with any type of printer connected to
        the parallel printer port. One of the following types of
        printers, or one which can emulate one of the following types, is
        required for printing graphics plots: Epson MX and FX 8/9-pin,
        IBM Proprinter 8/9 pin, and Epson LQ 24-pin dot-matrix printers;
        HP LaserJet printers; and monochrome and color HP DeskJet
        printers. Plotters are not supported.

        EZNEC can be run under Windows, Windows 95, or Windows NT as a
        DOS application (although some setup is required -- see
        INSTALLATION, p. 15). When running under Windows, the plots may
        be copied to the Clipboard, then to a Windows application and
        printed. 


                                INCOMPATIBILITIES

        EZNEC is incompatible with QEMM386 "stealth" operation, and use
        of "FRAME=NONE" with EMM386 (see "Resolving Incompatibilities",
        p. 25).






                                       13

























                                      EZNEC








                                 GETTING  STARTED




                                   INSTALLATION

        Installation differs somewhat with the kind of operating system
        you have. Special instructions are given for the various systems.

        The following instructions assume that you choose the default
        directory of C:\EZNEC for your program. If you install it in a
        different directory, you'll need to use its name in place of this
        directory where mentioned below. Also, if you install from the B:
        instead of A: drive, substitute its name in the following
        instructions. When told to enter text shown between quotation
        marks, type only what is between the marks, not the marks
        themselves.

                                 Running INSTALL

        Put the EZNEC disk into the A: drive and start the installation
        program as follows. For Windows 3.xx systems, click "File", then
        "Run". Enter 'A:INSTALL' into the box, then click "OK". For
        Windows 95 and NT, Click "Start", then "Run". Enter 'A:INSTALL'
        into the box, then click "OK". (Alternatively, the INSTALL
        program can be run from the DOS prompt in Windows systems.)

        If you haven't previously installed EZNEC: You will be prompted
        for a directory in which to install EZNEC. Pressing <Enter>
        following every prompt will result in creation of directory
        C:\EZNEC and installation in that directory.

        If you have previously installed EZNEC: If you install EZNEC in
        your EZNEC directory (recommended), the EZNEC files will
        overwrite your existing EZNEC program files (but will not alter
        or erase your description, ground, or configuration files). This
        is no disadvantage, since EZNEC has all the capabilities of the
        EZNEC program it replaces. It is recommended that you have
        INSTALL copy the program files to your EZNEC directory. Doing
        this will retain the same paths to your EZNEC files, which EZNEC
        will use. Specify the desired directory for installation when
        prompted.

        Follow the instructions on the screen during the installation
        process. 

        If you previously installed EZNEC and have chosen a different
        directory for installation than your current EZNEC directory: It
        is recommended that you put a copy of the ELNEC.CFG file from
        your EZNEC directory into your new EZNEC directory. Doing so will
        configure colors, paths, and other preferences the same for  as
        for EZNEC. After copying the ELNEC.CFG file to your new
        directory, run EZSETUP Ground File Utilities to make updated
        copies of your ground files. See RUNNING EZSETUP, p. 20.


                                       15




        This completes the installation for DOS systems. If you are using
        a Windows operating system, additional steps are required, even
        if you intend to run EZNEC only from a DOS prompt. Please follow
        the instructions for your particular system.

                         Windows 3.xx EZNEC Installation

        These steps are to be done after running INSTALL and doing the
        other steps above. First create a PIF (Program Information File)
        by double-clicking "Main", then "PIF Editor". Under "Program
        Filename", enter the full path and name of EZNEC.BAT. For
        example, if it's in EZNEC, enter 'C:\EZNEC\EZNEC.BAT'. In the
        "Start-up Directory" enter the same path as you did earlier, but
        without the file name ('C:\EZNEC', for example). You'll probably
        want to run EZNEC in a full screen, so make sure the "Display
        Usage: Full Screen" box is checked. If you want to include
        environment variables at this time (p. 136), enter them in the
        "Optional Parameters" box. In the box "XMS Memory: KB Limit",
        enter '-1'. This allows EZNEC to use all the memory it requires.
        Click "Advanced...", then under "Memory Options", click the "XMS
        Memory Locked" box so an "X" appears in it. This makes Windows
        report the actual amount of available RAM to EZNEC. Click "OK" to
        exit the Advanced Options dialog box. Click "File" in the PIF
        Editor, then "Save As", and enter "EZNEC". Close the PIF Editor.

        Finally, create the icon. In Program Manager, Click "File" on the
        menu line, then "New". Choose "Program Item", then "OK". In the
        "Description" box, enter the name you'd like to appear under the
        icon (such as EZNEC). In the "Command Line" box, enter
        'EZNEC.PIF'. (You may have to add a path to the PIF, such as
        'C:\WINDOWS'.) In the "Working Directory" box, enter the path to
        your EZNEC.BAT file (such as 'C:\EZNEC').

        You can modify the PIF and item properties later if you wish, but
        be sure that the XMS amount remains correctly set in the PIF
        Editor box.

                          Windows 95 EZNEC Installation

        EZNEC runs under Windows 95 as a DOS application. It can be set
        up to run under the DOS prompt, or in DOS mode. Each method has
        its advantages and disadvantages, described shortly.

        The interface portion of EZNEC is able to access only
        conventional memory (the lowest 640k of RAM). A few arrays must
        be used by this part of the program. Some increase in size with
        the number of wires in the description, and a few with the number
        of segments. Consequently, although unlikely, the amount of
        available conventional memory could possibly limit the antenna
        complexity to less than 500 segments.


                                       16




        Windows 95 has two types of DOS operation, DOS prompt and DOS
        mode. The former runs at the same time as Windows 95, permitting
        multi-tasking and other Windows features. DOS mode operation
        unloads the Windows 95 operating system except for a relatively
        small portion to facilitate re-starting it. The features of each
        method as they apply to running EZNEC are described next,
        followed by detailed instructions about how to effect each type
        of operation. Because it's quicker to start and exit, the DOS
        prompt method is recommended. However, if conventional memory
        availability becomes an issue, the DOS mode method may be
        preferable.

        DOS prompt (recommended)

        DOS prompt operation includes Windows 95 features such as multi-
        tasking and disk cache operation. This method is most convenient,
        because the program can be quickly started from the Windows 95
        environment, and return to the Windows 95 operating system occurs
        quickly after EZNEC terminates. The disadvantage of using this
        mode is that device drivers loaded with the CONFIG.SYS file can
        possibly use enough conventional or extended memory to limit the
        complexity of antenna EZNEC can model. The amount of memory loss
        depends on the number and type of drivers loaded in CONFIG.SYS,
        so may range from very little to a large amount, depending on the
        particular system setup. Users familiar with memory manager usage
        may be able to increase the available amount of conventional
        memory without adversely affecting normal Windows 95 functioning,
        but in general DOS mode operation gives more flexibility in this
        regard.

        DOS mode

        When DOS mode is started, a user-specified set of AUTOEXEC.BAT
        and CONFIG.SYS files can be used. This allows the user to
        optimize memory use for the particular application. The
        disadvantage of DOS mode operation is that EZNEC will take a
        relatively long time to start, and Windows 95 to resume after it
        has finished. The parameters suggested in the setup instructions
        which follow produce about 624k of available conventional RAM.
        This will allow EZNEC to easily model any antenna with up to 500
        segments (its limit).











                                       17




        Setup for either method

        Run INSTALL as described above, if you haven't already done so.

        From the main Windows 95 desktop, right-click "Start". Click
        "Explore". Locate the EZNEC.BAT file in the EZNEC directory.
        Click it once to select it, then right-click it. Select "Create
        Shortcut". "Shortcut to EZNEC" will appear in the Explorer
        listing. Drag this to the main desktop. A "Shortcut to EZNEC"
        icon should now be on the desktop. Close the Explorer. Right-
        click the "Shortcut to EZNEC" icon. Select "Properties", then
        "Program". Make sure that the working directory is your EZNEC
        directory. You can choose whether to click the "Close on exit"
        box. If checked, the system will return to Windows 95 as soon as
        EZNEC finishes. If not checked, the DOS window will remain open.
        This allows you to see any error message produced in the event of
        a crash or an error causing program termination. It is suggested
        that you leave this unchecked at least until you verify that the
        program is operating normally. Select "Screen". Under "Usage",
        select "Full-screen". Select "Program", then "Advanced".
        Continue, following the instructions for the method you choose.

        Setup for DOS prompt

        First do the operations in the "Setup for either method" section
        above. Then click "Prevent MS-DOS-based programs from detecting
        Windows" to check it. Click the two lower boxes as necessary to
        make sure that they do not have check-marks. Click "OK", then
        "OK" again.

        Setup for DOS mode

        First do the operations in the "Setup for either method" section
        above. Then click "MS-DOS mode" to check it. Click "Warn before
        entering MS-DOS mode" if necessary to make it not checked. Select
        "Specify a new MS-DOS configuration". (The following entries to
        CONFIG.SYS and AUTOEXEC.BAT won't affect normal Windows 95
        operation or operation of any other application.) In the
        "CONFIG.SYS" window, modify as necessary to make it read:

             DEVICE=C:\WINDOWS\HIMEM.SYS
             DEVICE=C:\WINDOWS\EMM386.EXE NOEMS NOVCPI
             DOS=HIGH,UMB

        Delete any other lines. Modify the "AUTOEXEC.BAT" window as
        necessary to read:

             SET WINBOOTDIR=C:\WINDOWS
             LOADHIGH C:\WINDOWS\SMARTDRV



                                       18




        No PATH, PROMPT, SET, or other statements are necessary in the
        AUTOEXEC.BAT window, except SET statements for EZNEC environment
        variables you may want to include (See ENVIRONMENT VARIABLES, p.
        136.) Click "OK", then "OK" again.

        Click on the Shortcut icon to run EZNEC. As mentioned above, you
        may want to set up shortcuts for both the DOS prompt and DOS mode
        methods. The DOS prompt can be used for smaller models when it's
        desired to have the program start and terminate quickly. The DOS
        mode can be used for more complex models when insufficient
        conventional RAM is available when using the DOS prompt. You can
        rename the shortcut icons by right-clicking them, then selecting
        "Rename".

        If you would like to enter the DOS mode and stay in it between
        times EZNEC is run, just follow the instructions above for the
        DOS mode, but in the Properties/Program section, enter 

             C:\COMMAND.COM

        in the "Cmd line" box. (You may have to enter
        C:\WINDOWS\COMMAND.COM instead, depending on where your
        COMMAND.COM file is located. In one computer tried by the
        developer, there was a copy in each of these directories.) You
        can check the "Close on exit" box in the same menu to make the
        system return to Windows 95 immediately after typing 'EXIT' at
        the DOS prompt.

                          Windows NT EZNEC Installation

        Introduction

        The following instructions have been tested with Windows NT
        Workstation v. 4.0. Installation on other systems may differ
        slightly, but must include two important steps:

        1. Normal installation of EZNEC onto the hard drive.
        2. Increasing the allotment of memory for the EZMAIN.EXE
           component of EZNEC beyond the default value allotted for DOS
           applications.

        In addition, a third step is convenient:

        3. Establishing a way to start EZNEC directly from the desktop.

                       
        Instructions





                                       19




        1. Install EZNEC.

        Follow the instructions under "Running INSTALL", above, if you
        haven't already done so.

        2. Increase EZMAIN memory allotment.

        From the Windows NT desktop, right-click "Start". Click
        "Explore". Locate the EZNEC directory in the left column and
        click its folder icon so its contents will show in the right
        column. In the right column, locate "Ezmain" and right-click it.
        Click "Properties", then the "Memory" tab at the top. Click the
        arrow to the right of the "Extended (XMS) memory" window and
        select "Auto". Change the selections in the other windows if
        necessary to make all windows except "Expanded (EMS) memory" show
        "Auto". The "Expanded (EMS) memory" window should show "None".
        The "Uses HMA" box should be checked, and the "Protected" box
        should be unchecked. When finished, click "OK". Leave the Explore
        window open.

        3. Establish a shortcut to EZNEC.

        In the right column of the Explore window, locate "Eznec" (not
        "Ezmain" as before) and right-click it. Click "Create Shortcut".
        "Shortcut to Eznec" should appear at the bottom of the right
        column. Drag the new "Shortcut to Eznec" icon out of the window
        and onto the desktop. Close the Explore window.

        To start EZNEC, double-click the "Shortcut to Eznec" icon. You
        can rename it if desired by right-clicking it and selecting
        "Rename". If desired, you can also start EZNEC by using the "DOS
        Command Prompt", going to the EZNEC directory, and typing
        'EZNEC'.


                                 RUNNING EZSETUP

        EZSETUP changes some of the values stored in file ELNEC.CFG,
        which EZNEC reads each time it's started (see EZNEC FILES, p.
        127). Other values are modified from the Options Menu within
        EZNEC. Parameters which you can modify with EZSETUP are:

           Printer type (several dot-matrix, laser, and DeskJet types)
           Printer port (parallel ports only, LPT1: through LPT4:)
           Printer initialization string (string to send to printer
                  before printing graphics; mainly used to set non-HP or
                  -Epson printers to compatible mode)
           Printer end string (string to send to printer after ending
                  graphics printing; mainly used to reset non-HP or -
                  Epson printers to normal mode)


                                       20




           Date format (mm-dd-yyyy, dd-mm-yyyy, or yyyy-mm-dd)
           Background color (background color for text displays on color
           monitors)
           Plot and cursor colors (for 2D pattern plots)
           Monitor type (useful only if you have a monochrome monitor
                  connected to a color adapter)
           Maximum number of MicroSmith .DAT file frequency steps (only
                  of interest if you have the MicroSmith program)
         
        The default values are:

           HP monochrome DeskJet or LaserJet III or later printer
           Printer port LPT1:
           No printer initialization or end strings
           U.S. convention date format (mm-dd-yyyy)
           Blue background
           Plot grid, total field plots white
           Horizontal polarization plot green
           Vertical polarization plot red
           Recalled traces assorted colors
           Color monitor
           Maximum of eight frequency steps in MicroSmith .DAT files

        EZSETUP can also be used to update EZNEC v. 1 ground files to the
        new format required by EZNEC v. 2 and to delete old-format ground
        files. See "Ground File Utilities" below.

        If the default values are satisfactory and you don't need to
        modify ground files, you don't need to run EZSETUP.

        In Windows systems, EZSETUP should be run from a DOS prompt. To
        start EZSETUP, go to the EZNEC subdirectory by typing 'CD EZNEC'
        (or other directory name if you've installed EZNEC elsewhere.)
        Then type 'EZSETUP'.

           Printer type

        Seven choices are currently available. If you don't know which
        type of printer yours will emulate, choose 8/9 pin Epson FX type
        for 8/9-pin dot matrix, 24 pin Epson LQ/compat. for 24-pin dot
        matrix, or HP DeskJet, LaserJet for laser printers or HP DeskJet
        printers. You can't damage your printer by selecting the wrong
        type, although you might get some very strange-looking plots!

        Dot Matrix Printers: If you have either an 8/9 or 24 pin IBM
        Proprinter, use the Epson MX driver. (Only 8-pin resolution will
        be available for the 24-pin Proprinter.) Otherwise, observe the
        following recommendations. In general, use the Epson LQ (24-pin)
        driver if you are using a 24-pin printer, and the Epson FX driver
        for an 8/9 pin printer. There are two choices of drivers for 8/9


                                       21




        pin printers. The Epson MX driver uses fewer graphics density
        options than the FX. Therefore it will work with a wider variety
        of printers, including IBM 8/9 and 24 pin printers. The plot it
        generates is somewhat smaller than FX driver plots, but you may
        get a faster plot with this driver on FX-compatible printers
        depending on your printer and computer hardware. Note that there
        are some dot-matrix printers which don't imitate the Epson
        printers. See PROBLEMS, p. 138.
         
        Laser Printers: If you are using an HP LaserJet III or later
        printer or compatible, you can use either the LaserJet or
        DeskJet/LaserJet III drivers. The two drivers use different
        formats to send data to the printer, so one may be faster than
        the other depending on your computer hardware. If you have a
        LaserJet, LaserJet II(), LaserJet 2000 or compatible, select the
        LaserJet driver.

        Monochrome DeskJet Printers: Select the DeskJet/LaserJet III
        driver if you are using a monochrome HP DeskJet printer or
        compatible.

        Color DeskJet Printers: The HP DJ color driver will handle all
        color DeskJets except the HP 500C. The latter requires special
        handling because of its inability to mix text and graphics on the
        same page. If you have an HP 500C, use the driver for that
        printer, otherwise use the HP DJ color driver. If you have a
        color DeskJet printer which doesn't work with the HP DJ color
        driver, please let me know the model number of your printer and
        the type of problem you're experiencing, and in the meantime use
        the HP DeskJet, LaserJet III driver. It's my intent to make EZNEC
        work with all the color DeskJets.

        Plotters: EZNEC does not support plotters.

           Printer port

        Leave this setting at LPT1: (parallel port 1) unless your printer
        is connected to a different parallel port.

           Printer initialization and end strings

        These are strings of characters which are sent to the printer
        before and after each graphics plot. Their intended use is for an
        owner of a non-HP or -Epson printer to have his printer
        automatically switch to an HP- or Epson-compatible (or emulating)
        mode and back. Consult your printer manual for the correct
        strings to send the printer. Generally these begin with "escape",
        which is ASCII character 27. Since "escape" is a non-printing
        character, you have to specify it in a special way for EZSETUP.
        Non-printing characters are entered as their ASCII character


                                       22




        number enclosed in "< >" characters. (Actually, any character can
        be entered this way if desired.) For example, 'escape'Ac* would
        be entered as <27>Ac*. If you need to include the characters "<"
        or ">" in the string, it's safest to enter them as their ASCII
        numbers of <60> and <62>, respectively. For example, the string
        'escape'Ac<9* would be entered as <27>Ac<60>9*.

           Background color

        This selection will change the background color of the text
        display on color monitors. It does not change the background
        color of the plot. If you have a monochrome monitor, select
        black.

           Other colors

        These select colors for the various parts of the 2D pattern plot,
        including the cursor. Note that EZNEC color drivers support only
        eight basic colors, and they may appear differently on the screen
        than on the printed output. You may have to experiment a bit to
        find a combination which will be satisfactory on both media.
        Yellow doesn't show up well on color printer outputs.
           
           Monitor type

        If you're using a monochrome monitor with a color adapter, some
        colors may not appear on the monitor. In this case, make the
        "Monochrome" selection. The "LCD" selection does the same thing
        as "Monochrome" but modifies the calculation progress
        "thermometer" display which may otherwise not reproduce properly.
        Use the "color monitor" selection for a color LCD.

           Maximum number of MicroSmith .DAT file frequency steps

        This choice is of interest only if you also have a MicroSmith
        program. (See MICROSMITH, p. 130, for more information.)
        MicroSmith versions 2.000B and earlier were able to handle only 8
        frequency steps in an imported .DAT file. If you have version
        2.000B or earlier, leave the value of this selection at its
        default value of 8. If you have version 2.000C or later, set the
        value of this selection to 100 unless told differently by your
        MicroSmith documentation.










                                       23




           Ground file utilities

        These are useful only if you have previously used EZNEC v. 1 on
        the same computer as the new installation of EZNEC v. 2. The
        EZNEC family of programs save ground files calculated with the
        Norton-Sommerfeld ("High Accuracy" ground) routines, for later
        use. Whenever a ground array has to be calculated,  EZNEC will
        first look to see if a ground file with similar values already
        exists. These ground files are saved in a directory specified in
        the EZNEC Options Menu and have the extension .EZG. EZNEC
        requires a different file format. So if you would like to take
        advantage of the files previously created by EZNEC v. 1, they
        must be converted to the new format. Choice 1 of this selection
        will make new-format copies of the existing ground files. Choice
        2 will delete the old-format files. The new files have extension
        .EG1. Unlike all other EZSETUP choices, these changes will be
        permanent even if you choose "Exit without saving changes" to end
        EZSETUP.

           Save choices and exit

        If you make this selection, the choices you've made will be saved
        in ELNEC.CFG.

           Exit without saving changes

        If you make this selection, ELNEC.CFG won't be changed. However,
        modifications done with the Ground File Utilities will be
        permanent.

                     MEMORY CONSIDERATIONS AND COMPUTER SETUP

        The amount of memory EZNEC requires is determined by the
        complexity of the antenna being modeled, the most significant
        factor being the total number of wire segments. (See MODELING THE
        ANTENNA STRUCTURE, p. 45, for more information on segments.)
        EZNEC requires just over 2 megabytes of available extended memory
        (RAM) to load and run. More space is required as antenna
        complexity increases. EZNEC will use additional extended memory
        if available; if not, it will use the hard disk as virtual RAM,
        writing, reading, and erasing temporary files on the disk as
        required. If your RAM or hard disk resources aren't adequate for
        the antenna, EZNEC will tell you and will not attempt to do the
        calculations. (See WHAT'S HAPPENING, p. 43.) EZNEC's
        implementation of NEC-2 (EZCALC) uses allocatable arrays, so
        memory is used only as needed and there is no fixed limit to the
        number of wires, loads, etc. as in the standard NEC-2 programs.

        Although the calculation portion of EZNEC -- which is very
        memory-intensive -- uses extended memory, the user interface


                                       24




        portion of the program does not. Therefore, if you have an
        unusually small amount of conventional memory (the lowest 640k of
        RAM) available and your model has a very large number of wires
        and segments, EZNEC may not be able to make all features
        function. In the unlikely event this happens, you will get a
        message when you attempt to use View Antenna for viewing current
        phase markers, currents, or antenna patterns. Or you may see an
        error message when you attempt other operations. If you see any
        of these messages, the cure is to unload any resident programs or
        other users of conventional memory, or to load them into upper
        memory using a memory manager. Or, you can reduce the number of
        wires and/or segments in your antenna model. Windows 95 users can
        avoid conventional memory problems by using DOS mode instead of
        DOS prompt operation Extended memory use is affected mostly by
        the number of segments. Conventional memory use is determined
        mostly by the number of wires.

        Since disk operations occur frequently in the course of normal
        EZNEC operation, a disk cache (such as Microsoft SMARTDRV,
        furnished with DOS and Windows) will speed operation a great
        deal. This may be true even if creating a disk cache reduces the
        amount of available RAM to the point that EZNEC has to use the
        disk for virtual RAM. If you're not familiar with disk caches and
        their use, see your DOS or Windows documentation regarding
        SMARTDRV.

        EZNEC doesn't require an extended memory manager to operate, but
        isn't bothered by the presence of one. A memory manager can
        increase EZNEC's maximum capability by increasing the amount of
        available conventional memory. Note that environment variable
        EZXMS must be used if EZNEC is operated without a memory manager.
        See ENVIRONMENT VARIABLES, p. 136. A memory manager is
        automatically loaded when Windows 95 DOS prompt operation is
        used.

        When running EZNEC as a DOS application under Windows, Windows
        may not allocate enough extended memory for EZNEC unless it is
        told to do so. See INSTALLATION, p. 15, for information.


                               MEMORY MANAGER SETUP

        There are two known incompatibilities involving memory managers.
        The first step in troubleshooting is to determine what memory
        manager you are using. Look in the CONFIG.SYS file in your
        computer's root directory for a line which says
        "DEVICE=...QEMM386..." or "DEVICE=...EMM386...". If you find
        either of these, please read the rest of this section. (QEMM386
        is a commercial memory manager by Quarterdeck Office Systems,
        Inc. Microsoft's EMM386 is furnished with DOS or Windows.) If you


                                       25




        found "...QEMM386", look for "/ST" or "/STEALTH" on the same
        line. This means that QEMM386 "stealth" mode, which is
        incompatible with EZNEC, is enabled. In this event, it is
        recommended that you run the "OPTIMIZE" program furnished with
        QEMM386 per the manufacturer's instructions, selecting 'No' when
        asked whether to use "stealth" operation. If you found
        "...EMM386", look for "FRAME=NONE" on the same line. If it
        appears, "FRAME=NONE" should be deleted in order for EZNEC to
        function properly.

                           RUNNING EZNEC UNDER WINDOWS

        EZNEC requires steps in addition to running INSTALL in order to
        be run under any of the Windows operating systems (Windows 3.xx,
        95, or NT). If you have not already done so, follow the
        installation instructions for your system, beginning on p. 15.
        After installation, EZNEC can be started by double-clicking its
        icon.

                  Inserting EZNEC Graphics in Windows Documents

        When running EZNEC from Windows as a DOS application, you can
        paste graphics screens (2D and 3D pattern plots, View Antenna
        display, and SWR graph) directly into Windows documents. When the
        display is on the screen, press 'V' or <CTRL>-'V' ('X' or 'Y'
        from the 2D plot only) to reverse the colors. Then press <PrtSc>
        (Print Screen) on your keyboard. (Nothing obvious will happen.)
        This copies the screen to the Windows clipboard. Minimize the
        EZNEC window by pressing <ALT>-<TAB>. Open your application and
        the desired document. (Example applications are WordPerfect,
        Word, Paintbrush, and Write, the simple word processor which
        comes with Windows 3.xx. This won't work with Notebook.) Select
        Edit/Paste in your application, or press <SHIFT>-<INS> to copy
        the plot from the clipboard to the document. If you need further
        help, see your application documentation regarding copying
        graphics screens from the Windows clipboard. <PrtSc> may not work
        for printing non-graphics screens (e.g., the Main Menu) when
        using Windows 95.

        A few users have reported that the resulting background is gray,
        rather than white, even though EZNEC uses bright white for the
        reverse-color background. It has been suggested that this might
        be correctable in some paintbrush-type programs at least, by
        limiting the number of colors in the paintbrush program.








                                       26

























                                      EZNEC









                            UPGRADING FROM EZNEC V. 1




                           DIFFERENCES FROM EZNEC V. 1

        EZNEC includes all the features of previous versions of EZNEC,
        plus a number of new ones. Some are briefly described below:

        Three-dimensional pattern: The full 3D antenna pattern can be
        shown. Individual azimuth or elevation "slices" can be
        highlighted to aid interpretation, and gain values displayed for
        any point. See "The 3D Pattern Plot Menu", p. 104, and "On The
        Race Course" (Test Drive), p. 40.

        SWR graph: A graph of the SWR of each source over a selected
        frequency range can be displayed. See "The SWR Graph Menu", p.
        114, and "On The Race Course" (Test Drive), p. 40.

        Two-dimensional plot features: A movable cursor appears on the 2D
        plot display, and the gain is shown at the cursor position. When
        a 3D plot has been generated, you can easily select which azimuth
        or elevation "slice" to display. See "The 2D Pattern Plot Display
        and Menu", p. 101.
         
        Near field analysis: Near field analysis is available, with
        output in tabular form only. Monitoring points can be stepped.
        See "The Main Menu", p. 74, and "The Near Field Setup Menu", p.
        115.

        Import wires: You can import wire definitions from an ASCII file.
        The imported wires can either be added to an existing
        description, or replace it. (See p. 132.)

        Create radials: Any series of connected wires can be replicated
        perpendicular to the Z axis to form radials. The radial structure
        doesn't have to be centered at the Z axis. See p. 91.

        Frequency scaling: You can now easily scale an antenna to a new
        frequency. (See pp. 74 and 67.)

        Combine descriptions: You can combine an EZNEC .EZ description
        file (wires, sources, loads, and transmission lines) with the
        current description. See p. 123.

        OpenPF plot file: EZNEC uses the OpenPF plot file standard for
        interchangeability with other programs. See p. 131 for more
        information.

        Frequency "sweep" using frequency list: A user-supplied list of
        frequencies can be used for the frequency sweep instead of
        uniformly spaced steps. See p. 135.




                                       28




        Comma-delimited file outputs: Most data outputs can be saved in a
        file in comma-delimited format for easier importing to other
        applications.

        To get acquainted with the features of the new 3D Pattern Plot
        display and the SWR Graph, take the new "On The Race Course" part
        of the Test Drive, beginning on p. 40.

        A few minor operational changes have been made to make operation
        more consistent. <ESC> is now universally used to exit displays
        and menus and to turn off functions. For example, you must now
        press <ESC> (rather than any key) to exit the 2D Pattern Plot
        display, and <ESC> will now turn off the graphical ANALYZE
        display.


                 USING ELNEC and EZNEC v. 1 FILES WITH EZNEC v. 2

        All EZNEC-family programs (ELNEC, EZNEC, and EZNEC PRO) will read
        description files created by any other program in the family.
        Plot files created by this and future versions of EZNEC conform
        to the OpenPF standard and are not readable with previous
        versions of ELNEC, EZNEC and EZNEC-M. Plot files saved with
        previous versions of ELNEC, EZNEC, and EZNEC-M (.ENT extension)
        are readable by EZNEC v. 2. Ground files must be converted with
        EZSETUP if it isn't done during installation (see EZSETUP "Ground
        file utilities", p. 24).

        ELNEC files require some modification, primarily because of
        different source and load placement. (Sources and loads are
        placed at segment junctions with ELNEC.) This is done
        automatically by EZNEC, and it tells you the changes it has made.
        If you read EZNEC files with ELNEC, you may need to move sources
        and loads, and change any split voltage or current sources.


                                    UPGRADING

        Follow the instructions in the INSTALLATION section on p. 15. If
        you install EZNEC into your EZNEC directory as suggested, it will
        use your existing ELNEC.CFG file. You won't have to run EZSETUP
        unless you are upgrading from ELNEC or from EZNEC prior to
        version 3.0 and want to use features which were introduced in
        that version.








                                       29

























                                      EZNEC








                                  RUNNING EZNEC




                                  STARTING EZNEC

        For information about running EZNEC as a DOS application under
        Windows 3.x, Windows 95, or Windows NT, see INSTALLATION, p. 15,
        and RUNNING EZNEC UNDER WINDOWS, p. 26. In DOS, make the EZNEC
        subdirectory the current directory by typing 'CD \EZNEC' (or, if
        you installed EZNEC in a different directory, the path to that
        directory). Type 'EZNEC' to start the program. It isn't
        recommended that you run EZNEC from any directory other than the
        one containing the EZNEC program files.


                         STARTING EZNEC IN TRACEVIEW MODE

        If you've saved traces (pattern plots), including 3D ones, and
        want to take another look at them, print them, or compare them
        without doing a new calculation, you can use the TraceView mode.
        This is done by typing 'EZNEC TV' at the DOS prompt. TraceView
        can also be used for viewing some plots created by other
        applications using the OpenPF standard. See TRACEVIEW, p. 126.


                     WHAT TO WATCH FOR WHILE EZNEC IS RUNNING

        While EZNEC is calculating, you'll see several "thermometers"
        which show the progress of the calculations. Progress may seem
        erratic at times, especially if the disk is being used for
        virtual RAM. This is normal.

        Two extra notices can appear near the top of the screen in bright
        letters. One notifies you that the disk is being used for virtual
        RAM because not enough free extended memory is available to store
        the necessary arrays in RAM. If you see this, there will be more
        disk activity, progress is liable to be more erratic, and a bit
        more time will be required to do the calculations.

        The other notice is shown when the stepped-diameter correction is
        being applied to one or more groups of wires. If it's being shown
        when you don't expect it or isn't when you are, investigate when
        the calculations are finished by going to the Wires Menu and
        typing 'C'. (See p. 90.)

                                    TEST DRIVE

        The best way to get familiar with EZNEC is to take it for a spin.
        Let's analyze a 20-meter dipole hung 30 feet up in the back yard.
        If you've started EZNEC, you should see the Main Menu. The file
        DIPOLE1.EZ is included on the disk and should be installed at the
        proper location, so we'll start with that antenna and modify it
        as necessary.


                                       31




        (Note: <Enter> means the Enter key, <ESC> is the Escape key. You
        may type any entry in uppercase, lowercase, or any combination.)
        Type all characters shown inside the single quotes (' ') but not
        the quote marks themselves.

                              Along the Straightaway

        From the Main Menu, type 'RE'. You don't have to follow it with
        <Enter>.

        You should see a list of all the antenna files in the default
        directory (there should be several). DIPOLE1.EZ should be on the
        list. If not, the antenna (.EZ) files are not installed where
        EZNEC can find them (EZNEC is looking for them in the directory
        named near the top of the screen). See "The Options Menu", p. 82,
        for instructions on setting the .EZ file path if DIPOLE1 doesn't
        appear. Assuming DIPOLE1 is on the list,

           Type 'DIPOLE1' <Enter>

        The TITLE shown near the top of the Main Menu should now read
        "Dipole in free space" -- this is the title of the antenna
        description stored in file DIPOLE1. Let's enter a title for our
        back yard dipole. As you type, notice the cursor near the lower
        right corner of the screen. The first letter you type will appear
        in this area. When you type the second, EZNEC will begin the
        desired action, terminate the entry, and erase both letters. If
        you type an unrecognized combination, the program will ignore and
        erase them so you can start over.

           Type 'TI'

        This brings up an entry area near the bottom of the screen.

           Type 'Back yard dipole' <Enter>

        Now the new title is entered and appears near the top of the
        menu. Let's change the frequency to 14 MHz --

           Type 'FR', then '14' <Enter>

        Let's choose feet for a convenient unit of measure.

           Type 'UN', then 'F'

        to select feet. Presuming you don't have a perfect ground plane
        in your back yard (and for many wavelengths in all directions),
        you'll want to do the analysis over "real" ground.

           Type 'GT', then 'R'


                                       32




        The height of the antenna will determine which ground model we
        use. If you have a fast computer, you can always choose High
        Accuracy analysis. Let's choose Fast analysis for now. That model
        is good with horizontal wires 1/10 wavelength high and higher,
        and it's fast.

           Type 'F' to choose (F)ast analysis.

        Now we're ready to describe the antenna itself.

           Type 'WI'

        which takes us to the Wires Menu. Since we're starting from a
        dipole description, the menu already shows one wire. We'll modify
        it to suit our circumstances.

           Type '1'

        Note the highlighted area which appeared at the wire 1, end 1
        coordinate area, and the prompt just below the wire description.
        Assuming our back yard dipole was designed using 468/f(MHz) to
        determine the length, the length is 33.43 feet. EZNEC doesn't
        require any symmetry, so for convenience we'll put one end of the
        wire at x,y = 0,0 and the other at x,y = 0,33.43. Placing it
        along the y axis makes the maximum lobes at zero and 180 degrees,
        in the direction of the x axis. Ground is always defined as being
        at z = 0 (for the innermost medium). Since the antenna is
        horizontal and up 30 feet, the z coordinate of both ends is 30.
        To enter the coordinates,

           Type '0,0,30', then press the right cursor arrow ->

        Pressing the arrow enters the value and moves the highlighted
        area, as in spreadsheet entry. Separate <Enter> and -> keystrokes
        also could be used.

           Type '0,33.43,30', then press the right cursor arrow ->

        Both end coordinates are now entered. The next prompt is for wire
        diameter (in inches or wire gauge). Supposing that the antenna is
        made from #12 wire, just

           Type '#12' <Enter>

        and the correct diameter is entered into the program. We could
        have entered the diameter in inches if desired. The last item on
        the line is the number of segments. 11 is a reasonable number for
        pattern analysis of a half-wave antenna, so we don't need to
        change it. (We do need an odd number of segments so we can put
        our source in the middle of the wire.)


                                       33




           Type <ESC> 

        to leave the wire description area. Before we leave the Wires
        Menu, let's see what the antenna looks like

           Type 'V'

        and the screen changes to show a three-dimensional display of the
        antenna. When finished viewing the antenna,

           Type <ESC>

        to exit the View Antenna screen and return to the Wires Menu.

           Type <ESC>

        to leave the Wires Menu and return to the Main Menu. Now let's
        put a source at the center of the dipole.

           Type 'SO'

        and note that we've gone to the Sources Menu. The specified and
        actual positions of source 1 are on wire 1, 50% of the way from
        end 1. This is where we want it. The amplitude, phase, and type
        of source won't have any effect on the pattern of a single-source
        antenna (as long as the amplitude isn't zero), so there's no need
        to change them.
           
           Type <ESC>

        to return to the Main Menu. Menu selection LO says that no loads
        are specified. Since our dipole doesn't have any networks
        inserted in it, zero loads is what we want. And we'll forego
        using transmission lines for now; we'll connect our source
        directly to the antenna for simplicity. Now let's look at the
        ground description.

           Type 'GD'

        and note that we've gone to the Media Menu. One medium is shown,
        with values corresponding to average soil. Suppose that our soil
        is very good.

           Type '1', then 'VG', <Enter>

        and note that the conductivity and dielectric constant have been
        changed to appropriate values for very good ground. To end the
        entry and leave the menu,

           Type <ESC>, <ESC>


                                       34




        We know that the dipole's maximum lobe will be at zero degrees,
        but at what angle above the horizon will it be maximum? We'll run
        an elevation plot to find out. (3D plotting is covered in "On The
        Race Course", the last section of the Test Drive.) Selection PT
        shows that an azimuth plot is the current choice, so

           Type 'PT', then 'E'

        Note that the plot type has changed to Elevation. The azimuth
        angle for the plot is zero degrees, which is where we'd like to
        look, and all the other parameters look fine. To plot the
        pattern,

           Type <Enter>

        When the plot is finished, note the choices in the upper right
        corner of the screen.

           Type 'A'

        to run an analysis of the plot. The values appear on the screen,
        and you can see the points on the pattern which ANALYZE found.
        This assures you that ANALYZE is measuring what you think it's
        measuring. If desired, you can print the annotated plot at this
        point by typing 'P'. This concludes the drive down the
        straightaway. If you'd like to try your hand at a little more
        complex maneuvering, try taking EZNEC. . .


                                Through the Curves

        If you haven't yet done so, take EZNEC "along the straightaway"
        above. In this section you'll begin with the plot generated by
        the "straightaway" drive and get introduced to a few of EZNEC's
        more advanced features. Several shortcuts are used in this
        section. Remember that they don't have to be used -- when you're
        using the program you can ignore them until you're more familiar
        with ordinary entry methods. And when you are ready to use them,
        there's usually a prompt on the screen to remind you how. Ready
        to go? Let's see how an inverted vee compares with our back yard
        dipole. First we'll save the dipole trace for future reference.
        With the "straightaway" plot on the screen,

           Type 'S'

        to save the trace. Enter a file name for the saved trace:

           Type 'BYDIPOLE' <Enter>

        then


                                       35




           Press <ESC> to turn off ANALYZE, then <ESC> again

        to return to the Main Menu.

           Type 'WI'

        to go to the Wires Menu. An inverted vee can't be made from just
        one wire since it's bent in the middle and all wires must be
        straight. So we'll have to add another wire and use each of the
        two wires for half of the inverted vee.

           Type 'A', then '1', <Enter>              

        to add a wire. Then

           Type '1'

        to select wire 1. Let's put the center of the antenna at 0,0,30
        (30 feet straight up from the origin). Note that end 1 of wire 1
        is already at this point, so

           Press the right cursor arrow ->

        to move to the other end of the wire. At this point, with other
        modeling programs you would have to do some trigonometry or
        carefully draw the inverted vee on graph paper to determine the
        coordinates of the end. But not with EZNEC. We'll start with a
        dipole and use EZNEC's Rotate feature to make it into an inverted
        vee. To make the inverted vee the same length as the back yard
        dipole, each wire needs to be 16.715 feet long. So

           Type ',16.715,' (note the two commas), then press the right
           cursor arrow ->.

        Since the x and z coordinates were already what we wanted, we can
        use an entry shortcut. You only have to enter the coordinate(s)
        you want to change, as you just did. The coordinates of end 2 of
        wire 1 should now be 0,16.715,30. Since the wires are half as
        long as before, half the number of segments should be adequate,
        so

           Press the right cursor arrow -> again, then Type '5'.

           Press the right cursor arrow ->, then the down cursor arrow

        to highlight end 1 of wire 2. Here's another entry shortcut: To
        connect this end to end 1 of wire 1,

           Type 'W1E1', then press the right cursor arrow ->



                                       36




        and note that the coordinates of wire 1 end 1 have been
        duplicated for wire 2 end 1, and that the end 1 Conn column shows
        the connection. For wire 2 end 2

           Type ',-16.715,30' (don't forget the comma).

           Press the right cursor arrow -> twice, then

           Type '5', <Enter>

        to select 5 segments for wire 2. EZNEC automatically makes the
        diameter of added wires the same as that of the wire just before
        the new ones, so this doesn't have to be changed. Let's take a
        look at our antenna so far.

           Type <ESC>, then 'V'

        to view the antenna. It should look like a straight wire.

           Type <ESC>

        to return to the Wires Menu. Now let's bend the wires down. The
        Rotate and Length change features follow the rule that only the
        selected end of the wire changes -- the other end stays put.
        Since we want the center of the antenna to stay put, this means
        we need to operate on end 2 of both wires.

           Type '1', then press the right cursor arrow ->

        to highlight end 2 of wire 1. Then

           Type 'RE-45', <Enter>.

        This tells EZNEC to Rotate the wire 45 degrees in Elevation; the
        minus sign means downward. Note the changed end 2 coordinates. To
        see what happened,

           Type <ESC>, then 'V'

        to view the antenna. You can see that the wire has been bent
        downward. (You may have to rotate the display with the arrow keys
        to make this apparent.) To return to the Wires Menu and bend the
        other one down:

           Type <ESC>, then Type '2', press the right cursor arrow ->,
           then

           Type 'RE-45', <Enter>

        to rotate the other wire downward. Let's take a look:


                                       37




           Type <ESC>, then 'V'.

        You should see an inverted vee.

           Type <ESC>, <ESC>

        to return to the Main Menu. Remember that we had one source in
        the center of wire 1 for our dipole. We need to move it to end 1
        of wire 1 or wire 2 to put it in the center of the inverted vee.

           Type 'SO', '1', '1,0', <Enter>

        to put the source at end 1 of wire 1. You also could have
        specified '2,0' for 0% from end 1 of wire 2. Or you could have
        entered 'W1E1' just like you do for wire end connections -- EZNEC
        will recognize that format, too.

        Take a look at the "(Specified)" column. This position of 1/0.00
        (wire 1, 0% from end 1) is what we asked for. But the "Actual"
        column tells us that the source was placed 10% of the way from
        end 1. Let's see why.

           Type <ESC>, <ESC>, then 'VA' to view the antenna.

        The source is the red (if you haven't changed from the default
        colors) circle on one of the wires.

           Press the left cursor arrow <- a couple of times

        to rotate the display for a better view. The source is at the
        center of a segment. All sources have to be at segment centers
        (as do loads and transmission lines), so we can't put the source
        at the junction. But EZNEC has a way out of this dilemma -- the
        split source. Go back to the Sources Menu: 

           Type <ESC>, then 'SO'.

           Type '1', then press the left cursor arrow <-

        to highlight the Type column.

           Type 'SI' to select a split current source.

        Notice that the "Actual" column entry now reads 1/0.00; the
        source has moved to the wire junction where we want it. Let's see
        what it looks like now. Go back to the View Antenna display:

           Type <ESC>, <ESC>, then 'VA'.




                                       38




        There are two sources, one on the segment at each side of the
        junction. EZNEC can't defeat NEC's internal structure, so it
        makes two sources and takes care of all the worries about making
        sure they're facing right, where they're placed, what values they
        need to have, and the like, and combines their outputs for you.
        Split sources look just like a single source in all displays and
        outputs except View Antenna. Their true nature is purposefully
        shown in the View Antenna display so you don't accidentally put a
        transmission line or unbalanced load on one of the segments the
        sources are on.

           Type <ESC>

        to return to the Main Menu, then

           Type <Enter>

        to generate the plot. When the plot is finished, notice that the
        gain is a bit lower than for the dipole. But how do the patterns
        compare? To find out,

           Type 'R', then 'BYDIPOLE', <Enter>

        to recall the dipole trace and superimpose it on the inverted
        vee. Note that when automatic outer ring scaling is selected,
        it's scaled for the largest of all the plots being displayed. It
        can be shown that the center of current for a sinusoidal
        distribution is 1/3 of the way from the current loop. This means
        that the effective radiation strength from the inner 1/3 of the
        inverted vee equals that from the outer 2/3 (since the current is
        heavier toward the center). If we raise the inverted vee by 3.94
        feet, it will place this current center at 30 feet, which was the
        height of the dipole's center of current. Let's try it and see
        what happens:

           Press <ESC>, then Type 'WI'

        to return to the Main Menu and go to the Wires Menu. To raise the
        antenna 3.94 feet, just

           Type 'H' then '3.94', <Enter>

        and all z coordinates are increased by 3.94 feet.

           Type <ESC>, <Enter>

        to return to the Main Menu and generate the new plot. When the
        plot is finished, it can be compared with the dipole trace:

           Type 'R', then 'BYDIPOLE', <Enter>.


                                       39




        The higher inverted vee is closer to the dipole pattern but still
        has slightly lower gain. This shouldn't be surprising if you
        investigate the patterns in more detail. The inverted vee has
        more radiation off the end, reducing the gain from the side. But
        as you can see, the gain difference between the dipole and
        inverted vee is less than one dB (providing the centers of
        current are at the same height).

                                On The Race Course

        This section takes you through some of the features new to EZNEC
        v. 2.

        Return to the Main Menu:

           Type <ESC>

        Recall the back yard dipole model included with EZNEC: 

           Type 'RE', then 'BYDIPOLE'

        Let's look at the full 3D pattern. This is done with the Plot
        Type selection in the Main Menu.

           Type 'PT', then '3'

        You'll see a brief message that the step size has been changed to
        5 degrees. This is to avoid making too dense a display. The
        minimum permitted for a 3D plot is 2 degrees, but this is too
        dense for general use.

           Press <Enter>

        to start the calculation. When the progress "thermometers"
        finish, you'll see a full three-dimensional (3D) display of the
        dipole pattern. You'll note that it doesn't look much like the
        textbook pictures you may have seen. This is because the textbook
        pictures usually show a dipole in free space or, at most, over a
        perfect ground. EZNEC can show you much more!

        You can move the 3D display around with the arrow keys to view it
        from different angles. If you hold a key down, a "skeleton" of
        the pattern appears briefly. This is a result of interrupting the
        relatively slow drawing process to speed rotation.

           Type 'H'

        to highlight a "slice". A small cursor is on the slice, at the
        origin (where the axis lines join). Press the up and down arrow
        keys several times to see that you can position the cursor


                                       40




        anywhere along the "slice". Notice that the gain at the cursor
        position is shown to the left of the display. By moving the
        cursor up and down, you can see that the maximum gain of 6.81 dBi
        occurs at an elevation angle of 35 degrees. Just under the cursor
        gain readout of 6.81 dBi, you should see "= 0.00 dBmax". dBmax is
        the gain relative to the pattern maximum. Because it shows as
        zero, you know that this is the point of maximum gain anywhere on
        the 3D pattern.

        Leave the cursor at the point of maximum gain, then

           hold down the <CTRL> key, and press the right arrow key ->

        while the <CTRL> key is being pressed. The highlighted "slice"
        will move. Press this combination several more times to see that
        you can select any elevation "slice".

           Press the left arrow key <- while holding down <CTRL>

        to move the selected slice the other direction. Then,

           hold down the <CTRL> key, and press the UP arrow.

        The highlighted "slice" changes to an azimuth "slice". Note that
        the readout on the left of the screen now shows this fact, and
        gives the elevation angle of the "slice". By using <CTRL> with
        the up and down arrow keys, select the azimuth "slice" at 35
        degrees elevation. Then use the arrow keys without <CTRL> to move
        the cursor to an azimuth of zero degrees. (If you're an EZNEC v.
        1 user who has set his readout for bearing instead of angle, set
        the cursor to a bearing of 90 degrees.)

        You can change between azimuth to elevation "slices" by pressing
        the <CTRL> arrow keys. <CTRL>-<UP> and <CTRL>-<DOWN> select
        azimuth "slices"; <CTRL>-<LEFT> and <CTRL>-<RIGHT>, elevation
        "slices". Note that when the "slice" type changes, the "slice"
        and cursor angles exchange.

        You might like to rotate the display while the "slice" is
        highlighted. Note the menu entry at the bottom of the menu area.
        It tells you that you can change the function of the arrow keys
        by pressing the space bar (<SPC>). Also note the very top menu
        item, which shows that the arrow keys change the cursor position.

           Press the space bar (<SPC>).

        Notice that the very top menu item now shows that the cursor keys
        rotate the display. Try rotating the highlighted display with the
        arrow keys, then pressing <SPC> and using the arrow keys to move
        the cursor. When you're finished experimenting,


                                       41




           Type 'R'

        to return the display to its initial highlighted position. Now

           Press '2'

        to go to the 2D display. Note that you can again move the cursor
        with the arrow keys, and select the slice with <CTRL> and the
        arrow keys. Operation is exactly like the 3D display. The "slice"
        type and angle, and gain at the cursor, appear at the bottom of
        the screen. You can run ANALYZE on any slice by pressing 'A'.
        Experiment with these functions. When finished, note the "slice"
        type and angle, and the cursor angle, at the bottom of the
        screen. Then

           Press <ESC>

        to exit. (If ANALYZE was on, the first <ESC> turns it off, so
        press <ESC> a second time to exit.) Notice that the "slice" type
        and angle, and the cursor position, is the same as it was when
        you exited the 2D display.

        One last point to mention before leaving the 3D display. You can
        save a 3D plot from this display (selection 'S'), but you can't
        recall one from the 3D display. You can specify its name when in
        the 2D display, and choose any azimuth or elevation "slice" for
        viewing in 2D. Or, you can recall and view the entire 3D plot
        with TraceView (see TRACEVIEW, p. 126).

           Press <ESC>

        to turn off the highlighted slice, then

           press <ESC> to exit the 3D display and return to the Main
        Menu.

        At the Main Menu

           type 'SW'

        to generate an SWR graph.

           Type '14,14.4,.1' followed by <Enter>.

        After the activity ceases, the SWR Graph should appear. Use the
        left and right arrow keys o see exactly what the SWR is at any of
        the analyzed frequencies. The graph clearly shows that the
        antenna is too long, if lowest SWR on 20 meters is a goal. This
        is indicated by the fact that the SWR decreases clear across the
        band.


                                       42




        You might want to feed the antenna with 75 ohm line instead of 50
        ohm line. An alternate Z0 is available for analysis. It's set in
        the Main Menu (selection 'SZ'). Since we didn't change it, its
        value is 75 ohms, which was the value in the DIPOLE1 description
        we started with. To see what the SWR would be on a 75 ohm
        feedline,

           press 'Z'.

        75 ohm feedline feeding this antenna would have a lower SWR than
        50 ohm line. (However, the SWR is low enough that it's unlikely
        to make any difference in performance unless the feedline is
        exceptionally long or lossy.) If analyzing an antenna with more
        than one source (such as the example antenna 4SQUARE), an
        additional menu item will appear allowing you to select the
        source for SWR graphing.

           Press <ESC>

        to return to the Main Menu and conclude the Test Drive.

        Now you've taken EZNEC for a good run. MODELING WITH EZNEC (p.
        43) gives tips for creating models and interpreting results. The
        REFERENCE MANUAL chapter (p. 70) contains complete information
        about each menu and its features.


                                 WHAT'S HAPPENING

        Quite a few processes occur during the course of EZNEC operation.
        EZNEC is controlled by the batch file EZNEC.BAT. This batch file
        starts EZMAIN.EXE, which contains the user interface and, in
        fact, all of the program except the calculation portion. When the
        program is told to begin calculations, EZMAIN writes several
        temporary files onto the disk and then ends. EZCALC is a modified
        NEC-2 program. Communication between EZMAIN and EZCALC is
        entirely by means of temporary disk files. After reading the
        input information, running, and writing results onto the disk,
        the calculating engine ends, and control is passed back to
        EZMAIN. EZMAIN reads the information left by the calculating
        engine and displays it.

        This whole process generally runs so quickly and smoothly
        (particularly if you're using a disk cache) that you may not be
        aware of all that's happening.







                                       43

























                                      EZNEC








                               MODELING WITH EZNEC




                             INTRODUCTION TO MODELING

        Skillfully used within its limitations, EZNEC can do a remarkably
        accurate job of predicting antenna performance. But remember, it
        is analyzing a model of an antenna, not an actual antenna. So its
        accuracy is always limited by the accuracy of the representation
        of the real antenna and its environment by the model. In some
        cases, the tools simply are not available to make an accurate
        representation, so approximate results are the best that can be
        obtained. For example, a parabolic reflector could be
        approximately modeled as a wire grid, but the representation will
        not accurately predict low-level lobes or characteristics
        sensitive to dish smoothness. As another example, the ground
        model, which assumes homogeneous ground, may not accurately
        predict performance of an antenna over ground with stratified
        characteristics.

        Other limitations are dictated by the numerical limitations of
        the underlying calculating code. A number of these are pointed
        out in this manual where appropriate.

        Finally, skill is involved. The ability to observe the results
        and determine whether they are reasonable requires some knowledge
        of the principles of operation of the systems being analyzed, as
        does the ability to make reasonable approximations to real
        situations.

        You may want to take the "Test Drive" in the previous chapter
        before or during the reading of this chapter.


                          MODELING THE ANTENNA STRUCTURE

        EZNEC models every antenna as a collection of straight wires. A
        round loop, for example, must be built out of short, straight
        pieces of wire. The diameter of each wire can be freely chosen,
        and the program will give accurate results with diameters from
        arbitrarily small up to at least 0.02 wavelength. With some
        imagination, nearly any type of conducting structure can be
        modeled as straight wires (although not always practically or
        with great accuracy). For example, a metal wall can be modeled as
        a grid of wires with a mesh on the order of 0.1 wavelength or
        less.

        You tell EZNEC where the wires are placed in space by giving
        their x, y, and z coordinates relative to a universal origin, or
        0,0,0 point. (See p. 71, 72 for an illustration of the axis
        system.) You're free to decide where the 0,0,0 point is, except
        that ground is always assumed to be at the height of the origin
        (z = 0). Also, if two media are used, the first medium is always


                                       45




        the one which exists at the origin, and only its characteristics
        are used for determining antenna impedances and currents. EZNEC
        has several features to make entry within the coordinate system
        as easy as possible; they're described in the REFERENCE MANUAL
        chapter, beginning on p. 70. Wires can be connected only at their
        ends; crossing wires won't connect them. (The calculating engine
        won't object to wires connecting at segment junctions. However,
        the connections won't be recognized by the interface portion of
        EZNEC, so errors can easily be made. Also, any change in wire
        length, orientation, or number of segments will break the
        connections. Therefore, attempting to make connections at other
        than wire ends is strongly discouraged.) Modeling an "X" - shaped
        structure with the recommended restrictions requires four wires
        if the crossmembers are connected at the center of the "X". See
        also CONSIDERATIONS FOR MODELING WIRES, p. 47.

        Wires are connected whenever an end of both have the same
        coordinates (actually, if  the ends are within about 0.001
        segment length of each other). If a ground plane (either perfect
        or "real") is used, a wire is connected to ground if its z
        coordinate is zero. (NOTE: For High Accuracy and Fast analysis
        type grounds, the connection will be quite lossy (resistive). See
        MODELING GROUND, p. 54).

        Each wire is divided into segments for analysis purposes. The
        EZNEC NEC-2 calculating engine assumes that the current has an
        essentially sinusoidal shape over the length of a segment, and
        that the currents of adjacent segments match at their junctions.
        This makes the problem one of finding a finite number of
        impedances, currents, and field strength contributions. Some of
        the skill part of modeling comes into play in choosing the number
        of segments. EZNEC will choose for you if you wish, but its
        choice may not always be best. Although accuracy improves when
        more segments are specified, computation time increases
        approximately as the square of the number of segments. A useful
        rule of thumb is 10 segments per half wavelength for pattern/gain
        analysis, and perhaps twice that number if really accurate
        impedance values are required. Be aware, however, that more --
        sometimes many more -- may be required under some circumstances.
        For example, wires joining at very acute angles may require more
        segments (see p. 53). If in doubt, a straightforward way of
        telling whether you've specified enough is to increase the number
        and see how much the results change. You should also develop the
        habit of looking at the currents on the wires. Abrupt current
        changes may indicate an insufficient number of segments (but note
        that apparently abrupt phase reversals at wire end connections
        may be due to internal conventions of assigning current direction
        -- see INTERPRETING THE RESULTS, p. 63). One place more segments
        aren't better is if wires of different diameters are connected in
        a configuration which EZNEC can't correct with its stepped


                                       46




        diameter correction. (See p. 51, "Wires With Different
        Diameters".) Determining a reasonable number of segments isn't as
        hard as it sounds. You'll soon get a good feel for about how many
        you need to get the shape of a pattern or a feedpoint impedance
        with the accuracy you need.

        Several NEC-2 guidelines are checked by the automatic Guideline
        Check. It runs automatically when you recall a file or change the
        wire description, or you can run it manually any time. There are
        two sets of guidelines: conservative and minimum recommended. In
        general, the conservative guidelines will result in more segments
        and better accuracy than the minimum recommended. It's impossible
        to place an accuracy figure on either set of guidelines, because
        the effect of small errors in current amplitude or distribution
        can vary greatly, depending on the type of antenna and the role
        the wire plays. As a general rule, you should use more
        conservative guidelines when modeling antennas which have a
        narrow bandwidth or use parasitic elements, such as a Yagi. For
        more information, see p. 81. Bear in mind that the Guideline
        Check doesn't report all possible errors, so care and knowledge
        on the part of the user is still required. Also, some antennas
        may require many more segments than the Guideline Check considers
        adequate.


                        CONSIDERATIONS FOR MODELING WIRES

                                     General

        Wires can be connected only at their ends. This is done
        automatically if the end coordinates of the wires are equal.
        Serious errors will occur if wires cross or occupy the same
        space. Modeling the following 3 X 3 cell wire grid
                                  ________  
                                 |  |  |  |
                                 |__|__|__|
                                 |  |  |  |
                                 |__|__|__|
                                 |  |  |  |
                                 |__|__|__|

        requires 24 wires; each side of each square is a separate wire.

        A common problem involves wire spacing. When wires are to be
        close but not connected, users frequently put them very close,
        sometimes a fraction of an inch or centimeter when the wavelength
        is tens of meters. This isn't good practice, and can lead to
        numerical problems. (It's difficult for any program to deal with
        wires which are 40 meters long but spaced .0001 meter apart.)
        Always use realistic spacings. If you're analyzing a 3 MHz


                                       47




        antenna, you probably can space wires six inches (15 cm) without
        materially affecting the antenna operation. If you can, do so. If
        you can't, make sure the results aren't unduly sensitive to the
        spacing or number of segments. If they are, numerical problems
        may be occurring. More information about closely spaced wires and
        wires intersecting at an acute angle is given in the paragraphs
        below. 

                                "Crossed Dipoles"

        To model two dipoles fed at a common point (sometimes called
        "crossed dipoles" -- see figure below), feed by inserting a wire
        between the pairs of dipole halves and place the source on the
        wire. The wire length should be a minimum of 0.02 wavelength, and
        it should have three segments. (See p. 57.)

                              .           .    
                               \         /
                                \       /
                                 \__0__/
                  dipole halves  /     \  dipole halves
                                /   ^   \
                               /  source \
                              .           .

                          "Crossed dipole" model                 


                               Closely Spaced Wires

        NEC-2 documentation recommends aligning the segments of closely-
        spaced wires. That is, arrange for the segment junctions to be
        beside each other, rather than offset. It may be necessary to use
        a larger than normal number of segments for closely spaced wires.
        If in doubt, change the number of segments and see if the results
        change significantly. In any case, spacing should be at least
        several wire diameters.

                             Elevated Radial Systems

        A number of people have showed an interest in modeling systems of
        radial wires placed at very low heights above ground. A system of
        very low wires can be used to simulate the performance of buried
        radials. Experiments were done comparing various modeling codes,
        resulting in the following guidelines:

           1. The minimum recommended height for modeling ground radial
           systems is 10-4  wavelength, or the diameter of the vertical
           wire, whichever is greater.



                                       48




           2. No special techniques are required if the radials are at a
           height of at least 0.001 wavelength and at least the diameter
           of the vertical wire. Ordinary segmentation can be used. Even
           stepped diameters don't seem to require special attention in
           this situation. This height is recommended for simulating
           buried radials or radials placed on the surface of the ground.

           3. If the radials are between .001  and .0001 wavelength high,
           segment length tapering should be used (see p. 67). The
           minimum segment length should be made equal to the height of
           the radial system. The default maximum is adequate. When
           prompted for the minimum, maximum segment lengths in the
           tapering process, enter '#,' where # is the height of the
           radial system above ground in current units. When placed on
           such a short wire, the source must be surrounded by equal-
           length segments. After tapering, combine the source wire and
           the one above into a single wire with 3 segments, then move
           the source to the center of this wire. If, for example, the
           original vertical wire was wire 1, with end 1 at the bottom
           (as in example file ELEVRAD1.EZ), first taper all wires. Then
           select end 2 of wire 1 and enter 'W2E2' to make its
           coordinates the same as end 2 of wire 2. Change the number of
           segments of wire 1 to 3. Then delete wire 2. Finally, move the
           source to the center of wire 1. The result should look like
           ELEVRAD2.EZ.

        I don't know of any good experimental measurements of the sky-
        wave field strength from verticals with elevated radial systems.
        There are a few ground-wave measurements. EZNEC (and NEC-2) show
        ground-wave field strengths for elevated systems which are
        stronger than some measurements seem to indicate, particularly at
        frequencies of 3 MHz and below, so there may be some doubt about
        the accuracy of the signal strengths reported by EZNEC for
        elevated radial systems.

                               Feedlines and Baluns

        The radiation properties of a coaxial feedline can be modeled by
        connecting a wire of the coax shield's diameter to the point on
        the antenna where the shield connects. The wire is then routed
        (using additional wires to simulate bends) to ground along the
        path taken by the actual feedline. The ground path from the
        transmitter/receiver should be included, with wires of
        appropriate size. This can be done whether or not an EZNEC
        transmission line model is used to model the inside of the
        feedline. (See USING TRANSMISSION LINES, p. 59, for more
        information about using transmission line models.) The job of a
        "current balun" or "choke balun" is to insert an impedance in the
        path formed by the outside of the shield. To model a balun,
        insert a load in series with the "coax" wire (the wire simulating


                                       49




        the outside of the coax) at the point where a balun would be
        placed. A good balun will have an impedance of the order of 500-
        1000 ohms, and may be resistive, reactive, or a combination
        depending on construction. Accurate modeling requires knowledge
        of the balun impedance at the frequency of interest. The balun
        generally reduces the current in the "coax" wire, which means
        that the current on the outside of the actual coax feedline is
        reduced. It sometimes is necessary to insert more than one balun
        (quarter-wavelength spacing is typical) to reduce feedline
        outside current to a low level. Coaxial feedlines connected to
        "unbalanced" antennas like ground plane antennas aren't immune to
        induction of current, either. 

                              Linear Loaded Antennas

        "Linear loaded" antennas (generally Yagis) are physically
        shortened by attaching to the elements wires which are parallel
        to, and spaced close to, the elements. EZNEC will not give
        accurate results for this type of antenna unless all the wires of
        a given element are the same diameter. This is due to NEC-2's
        inaccuracies when dealing with connected wires of different
        diameters and the fact that even small parasitic element errors
        have a major effect on the performance of a beam antenna. The
        "stepped-diameter correction" used by EZNEC is not accurate and
        will not be invoked for typical linear loaded elements.

                              Log Periodic Antennas

        An integral part of log periodic antennas is the transmission
        line connecting the elements. This must be included in the model,
        since no valid assumptions can be made about the relative
        voltages and currents at the element centers. Transmission line
        segments between elements can be included as either wire models
        or as transmission line models. Examples of both are included on
        the disk.
         
                                Multiband Antennas

        EZNEC is well-suited for modeling multiband antennas. Keep in
        mind the segment length, however. Remember that as you increase
        the frequency the segment length increases in terms of
        wavelength. In general, you should double the number of segments
        each time you double the frequency. A bare minimum number of
        segments for a square loop is about four per quarter wavelength.
        This means four segments per side at the frequency at which the
        loop is a full wavelength in circumference, eight per side at
        twice the frequency, etc.





                                       50




                                 Shunt Fed Towers

        Reasonable accuracy can be expected in modeling shunt fed towers,
        but with some restrictions. First, MININEC-type ground must be
        specified, with added resistive loads to simulate ground system
        resistance; or High-Accuracy ground must be used with above-
        ground radials to simulate buried ones. (See MODELING GROUND, p.
        54.) Second, the main tower can't generally be modeled as a
        single large-diameter wire. The combination of attachment and
        close spacing of wires of very different diameters results in
        substantial inaccuracy, or even numerical calculation errors. The
        legs of the towers should be modeled directly, with occasional
        cross-wires. I don't have enough information to make firm
        recommendations about how many cross-wires are necessary, but
        they should probably be more frequent in the region of the shunt
        feed wire. Remember that wires can be connected only at ends, so
        the tower legs will have to be modeled as several connected
        vertical wires, with cross-wires connected only at their
        junctions.
         
                                   Small Loops

        EZNEC is unable to accurately model small (circumference less
        than about 0.1 wavelength) loop antennas. If this is attempted, a
        zero or negative feedpoint impedance may result, and the
        indicated gain may be -99.99 dBi.

               Wires With Different Diameters ("Stepped Diameter")

        NEC-2 is known to be inaccurate in modeling connected wires
        having different diameters. (Note: This is sometimes called being
        "tapered". In EZNEC, the term "tapering" refers to segment length
        tapering.) The problem gets worse as the segments near the
        junctions get shorter and as the diameter difference gets larger.
        The error is small enough that it's not important for many
        applications, such as evaluating a tower top-loaded with a beam.
        However, in applications involving parasitic elements or high-Q
        circuits, the inaccuracy can cause significantly bad results.
        EZNEC incorporates a method developed by Dave Leeson, W6QHS, for
        calculating an equivalent wire of constant diameter to replace a
        group of wires of different diameters. The method is valid only
        under a narrow range of circumstances, however, and EZNEC will
        apply it only under those circumstances. The requirements are
        that:

            - There must be at least two wires in the group.
            - At least two of the wires must have different diameters.
            - All wires in the group must be collinear (in a straight
              line).
            - All wires must be connected to each other.


                                       51




            - Both ends of the group must be open, or one end open and
              one connected to ground.
            - The group must be nearly resonant (within about 15% of
              half-wave resonance if both ends are open, or within about
              15% of quarter-wave resonance if one end is grounded).
            - Only one source is permitted in the group, and it must be
              at the center if the ends are open, or at the bottom
              segment if the group is grounded. Loads must be
              symmetrical. No transmission lines are permitted on the
              group of wires.

        These criteria apply to typical Yagi elements made from
        telescoping tubing, one of the most demanding cases where the
        correction is needed. The correction won't be applied to a gamma
        match, another sensitive application, so attempting to model
        gamma matches isn't recommended if very accurate results are
        required.

        A bright notice will appear on the EZNEC screen during
        calculation when the stepped-diameter correction is being used
        for one or more groups of wires. You can see exactly what the
        substitutions are from the Wires Menu by typing 'C'. (See p. 90.)

        The correction can be disabled from the Options Menu if desired,
        but this isn't recommended.

        In situations where wires of different diameters are connected
        but EZNEC's stepped-diameter correction doesn't apply, the error
        can be minimized by using the SMALLEST number of segments
        possible, and not using segment length tapering. (Exception:
        wires very near ground. See "Elevated Radial Systems", p. 48.)
        The accuracy of EZNEC is worst in the presence of stepped
        diameters when the segment length/diameter ratio is small.
        Especially when confronted with a large difference in diameters,
        the best accuracy will be obtained if you use the automatic
        segmentation feature in the Wires Menu, and select (M)in.
        recommended. The accuracy is still not good enough for accurate
        modeling of parasitic elements if the built-in correction can't
        be applied.

        The inaccuracy of NEC-2 in the presence of large steps in
        diameter typically shows up as an incorrect reactance. If you
        design an antenna with parasitic elements having connected wires
        with largely differing diameters, EZNEC will give a reasonably
        accurate idea of the performance the antenna is capable of.
        However, it will show the performance occurring at a somewhat
        incorrect frequency. When you actually build the antenna, you can
        expect the predicted performance, but may need to adjust
        parasitic element lengths to achieve that performance at the
        desired frequency. For example, if EZNEC shows your "X-beam" to


                                       52




        have a gain of 5 dBi, front/back ratio of 20 dB, and feedpoint
        SWR of 1.5:1 at 14 MHz, you may find when you build it that the
        front/back ratio is much worse than predicted at 14 MHz but is
        very good at 14.5. In this case, you would need to lengthen the
        parasitic element until you get the best front/back ratio at 14
        MHz. The beam will then have very nearly 5 dB of gain and 1.5:1
        SWR at 14 MHz.

                         Wires Joining at an Acute Angle

        NEC-2 has some difficulty in accurately modeling multiple wires
        joining at a very acute angle. The problem has a different cause
        than the MININEC problem of "cutting corners", and quads are
        modeled very well by EZNEC without special attention. However,
        when modeling very acutely-intersecting wires, evaluate the
        results carefully, particularly if a source or load is at or near
        the junction. It has been reported that EZNEC's "segment length
        tapering" feature (originally developed for MININEC-based ELNEC)
        improves the accuracy in this situation, provided that the wires
        all have similar diameters. Tapering is likely to degrade the
        accuracy with wires of greatly different diameter. (Exception:
        wires very near ground. See "Elevated Radial Systems", p. 48.)
        Another method which has been reported to work is to put a
        separate source on each wire, rather than a single one near their
        junction.

        Some NEC-2 literature cautions against permitting the center of a
        segment to lie within the volume of another wire. This can occur
        when segments are short, wires have large diameters, and
        intersection angles are acute. EZNEC doesn't check for this
        condition. Although it seldom seems to cause trouble, I do
        recommend that you avoid this situation as a general practice.

        A case was found where EZNEC produced results which were very
        inaccurate, and showed great sensitivity to the number of
        segments. This case was where a wire approached the middle of
        another at an angle, but wasn't connected, like an insulated guy
        wire at the midpoint of a tower. Reliable results were obtained
        only by spacing the end of the "guy wire" from the "tower" by
        about a segment length. With slightly closer spacings, reasonable
        results were obtained by making sure the segment lengths of both
        wires were the same, and the junctions were directly across from
        each other, as viewed through the bisector of the angle they
        formed.








                                       53




                                 MODELING GROUND

                                Ground Model Types

        EZNEC provides free space, perfect ground, and three different
        "real" ground environments. All grounds are flat and infinite in
        extent.

        The three "real" grounds are MININEC-type, Fast Analysis, and
        High-Accuracy. The MININEC-type ground considers the ground to be
        perfect when calculating the impedances and currents. Like the
        other real ground models, it takes ground conductivity and
        dielectric constant (relative permittivity) into consideration
        when it calculates the pattern and gain. The MININEC-type ground
        leads to the fastest calculation times, and is satisfactory if
        the antenna doesn't contain any horizontal wires which are lower
        than about 0.2 wavelength. The MININEC-type ground is preferable
        when modeling grounded wires, such as verticals. It doesn't cause
        a resistance to be inserted in series with the grounded wire, as
        happens with the other real ground types (see below). When using
        MININEC-type ground, a load must be added to grounded wires at
        the grounded segment to simulate ground system loss.

        The Fast Analysis ground uses the NEC reflection-coefficient
        method to determine antenna impedances and currents. This method
        is also fast, and gives good results provided that the antenna
        doesn't include any horizontal wires lower than about 0.1
        wavelength.

        The High-Accuracy (NEC Sommerfeld) ground is the most accurate
        for antennas with low horizontal wires. (The minimum height
        depends on several factors, but results should be good down to at
        least 0.005 wavelength, or about 6 inches -- 15 cm -- at 30 MHz.)
        When High-Accuracy ground is used, a ground interpolation table
        is calculated. Although this can be a bit time-consuming, the
        resulting table is saved on the disk (as a "ground file). If
        future runs require a table with similar values, an already-
        calculated table is read and used instead of repeating the
        calculations. The key parameter which determines whether an
        existing table is close enough is the ground's complex
        permittivity (which is a function of the frequency and the ground
        conductivity and permittivity). If a table is found for a
        magnitude within a user-specified tolerance of the required
        magnitude, it will be used. You can change this tolerance, if
        desired, from the Options Menu. A tolerance value of a few
        percent is adequate where horizontal wires aren't extremely close
        to the ground. In situations requiring high accuracy, or where
        there are low horizontal wires, a much smaller tolerance, perhaps
        0.05%, is recommended.



                                       54




                               Connection to Ground

        If you connect a wire to ground when using the High-Accuracy or
        Fast Analysis real ground types, the program makes the connection
        with an unpredictable series resistance. EZNEC will warn you when
        this situation occurs.) Use the MININEC-type ground when modeling
        antennas with grounded vertical wires if the ground system itself
        isn't part of the model.

        A Wire end is connected to ground by specifying a zero z-
        coordinate. EZNEC considers a wire end to be connected to ground
        if it is within 1/1000 of a segment length of ground. A good
        general practice is to space unconnected vertical or sloping
        wires at least several wire diameters above ground.

                                   Buried Wires

        Buried wires cannot be modeled with EZNEC.

                                 Using Two Media

        The ground may be broken into two "media", each having its own
        conductivity and dielectric constant (relative permittivity). The
        second medium can be at a different height, but must be at the
        same level or below the first medium. The media can be arranged
        in parallel slices or concentric rings. One use of two media
        would be to model an antenna on a lake surrounded by land. Be
        careful when using two media. Even if you place the antenna on
        the second medium, EZNEC will always use the ground constants of
        the first medium for calculation of the impedances and currents.

                             Real Ground Limitations

        EZNEC's ground model may not be representative of some real
        ground situations. At lower frequencies, current penetration
        becomes deep, with skin depth being on the order of several
        meters at the lower end of the HF range. Real ground is likely to
        be stratified, with widely varying conductivity and dielectric
        constant within this depth range. Because NEC-2, therefore EZNEC,
        assumes a perfectly homogeneous ground of infinite depth, the
        model may not accurately reflect the antenna's actual
        environment. While NEC-2 is believed to be accurate in its
        evaluation of the model, it cannot accurately predict antenna
        performance if the model does not adequately represent the real
        situation. Consequently, EZNEC results for antennas with very low
        horizontal wires, particularly at lower frequencies, may be of
        limited usefulness in predicting actual antenna system
        performance. EZNEC is not able to model ground as being composed
        of other than a single homogeneous material of infinite depth.



                                       55




        Another factor limiting the ability to predict antenna
        performance when ground is a major factor is that actual ground
        conductivity appears to vary with frequency, an effect not
        modeled by EZNEC. Consequently, conductivity values for
        frequencies other than the frequency of use may not be accurate.


                                   USING LOADS

        Lumped impedances can be inserted into the wires if desired. Like
        sources, these are easy to place with EZNEC, and appear in series
        with the wire. Loads always appear in series with a source,
        transmission line, or other load placed on the same segment.
        There is no direct way to place a load in parallel with them.
        Loads are useful to simulate loading coils, capacitors in
        capacitive-loaded antennas, traps, and losses. They can be
        specified as either an impedance in R + jX form or as a quotient
        of Laplace transform polynomials. Automatic conversion of series
        or parallel RLC circuits to Laplace transform coefficients is
        provided. See "Using Laplace transforms", p. 96.

        Loading coils frequently have a significant amount of loss which
        should be included in the model. Measurement is the best way of
        determining the loss, but even a guess may be adequate. Air-wound
        inductors typically have Q's in the range of 200-400 or so. This
        means that you can estimate the equivalent series R as about
        1/200 to 1/400 the reactance. If using this range of values
        impacts your result, you may want to make a measurement or better
        estimate of the Q.

        A trap has a primary resonance at only one frequency, but trap
        antennas are operated at other frequencies as well. The only way
        to accurately model the trap is either by measuring its impedance
        at each frequency of interest, or by knowing the equivalent L, C,
        and R components, and how R varies with frequency. These in turn
        must be measured unless you can talk the manufacturer out of this
        information (or have constructed the trap yourself out of known
        components). Traps frequently will cause a couple of dB loss at
        one frequency or another, so failure to include loss resistance
        will lead to overly optimistic results.

        To place a load at a wire junction, split it into two equal loads
        of half the value and place each one on the adjacent segment.
        When EZNEC spots identical loads on segments adjacent to a wire
        junction, it shows voltages, currents, impedances, and losses of
        the combination as well as the individual loads, in the Load Data
        output.

        In critical applications, the same restrictions should be applied
        to loads as to sources regarding placement. Like a source, a load


                                       56




        is actually distributed along the entire segment upon which it's
        placed. See USING SOURCES, next.


                                  USING SOURCES

        Four source types are available with EZNEC: voltage, current,
        split voltage, and split current. When you specify a "split"
        source, EZNEC actually creates two sources, and places them on
        the segments adjacent to the segment junction closest to the
        placement you specified. Split sources are shown in View Antenna
        as two sources, but appear everywhere else as a single source.
        Split sources are included so you can place sources at wire
        junctions, such as on an inverted vee antenna. When using split
        sources, make sure that any load placed on the segment containing
        one source has a corresponding load on the segment containing the
        other, and avoid putting transmission lines on segments with
        split sources. Split sources can't be placed at a multiple-wire
        junction.

        Another way to put a source at a wire junction is to insert an
        additional short wire at the junction, and place the source on
        it. Unless a transmission line is in parallel with the source,
        the wire containing the source should have at least three
        segments and be at least 0.02 wavelength long. Experiments have
        shown inaccuracies to result if these guidelines aren't followed.
        If a transmission line is in parallel with the source, the wire
        can be very short and have a single segment. If a source is
        placed at a multiple-wire junction, the source should be placed
        on a short segment, and all the wires connecting to the junction
        should have a short segment at the junction end. The segment
        lengths can be "tapered" away from the junction, using EZNEC's
        Segment Length Tapering feature (p. 67).

        Sources are connected in series with the wire (as though the wire
        were broken and the source inserted). A voltage or current source
        appears in parallel with a transmission line connected to the
        same segment, and in series with a load in the same segment.
        Technically, a source is distributed over the entire segment at
        which it's connected; you can envision it as being inserted at
        the center of the segment. These connections are dictated by the
        structure of NEC.

        The magnitudes of the sources can be absolute or relative. If a
        power level isn't specified in the Options Menu, they're
        absolute. If power is specified, the source magnitudes and phases
        retain their same relative values, but all currents and voltages
        on sources, loads, and wires are scaled for that power level.
        This allows you to see, for example, the voltage across a trap
        for a given power input to the antenna. The specified power level


                                       57




        refers to the total power from all sources. The source powers
        can't be specified individually.

        Whether a source is constant current or voltage can make a large
        difference in the performance of any antenna with multiple
        sources, but makes no difference if the antenna contains only one
        source.

        No more than one source is permitted on a given segment.

        Even though sources appear in the View Antenna display to be
        placed in the center of a segment, the source is actually
        distributed over the entire segment. If source placement is
        critical (for example, in a base-fed half-wave vertical or
        center-fed full-wavelength dipole if impedance is important), the
        length of the segment containing the source can become important.
        The shorter the source segment is made, the more closely it
        imitates one connected at a single point. A simple test can show
        if this is important. Divide the wire containing the source into
        a reasonable number of segments. Run the program and note the
        results which are important to you (such as gain, or impedance).
        Move the source over one segment and repeat. If the results
        change more than you're willing to accept, you'll need to
        minimize the length of the source segment. One way to do this is
        to use segment length "tapering". See p. 67 for more information
        on using this technique.

                                  Phased Arrays

        EZNEC allows you to model phased array feed systems provided that
        they are made exclusively of transmission lines, and provided
        that the transmission lines don't interact with the antenna as
        wires. (EZNEC doesn't model coupling to transmission lines.)
        Examples of transmission line fed phased arrays are on the disk.
        To investigate various possible patterns, instead of modeling
        transmission lines, place a current source at each element's
        feedpoint and vary the element currents by changing the source
        magnitudes and phases. A very valuable capability of EZNEC is to
        tell you what the element feedpoint impedances are when an array
        is correctly fed. This information is required to design a feed
        system to produce the desired current ratio. To determine the
        impedances, insert current sources at the feedpoints, with the
        currents being in correct ratio. Entering 'SD' (Source Data) from
        the Main Menu will tell you the feedpoint impedances. 4SQUARE.EZ
        and CARDIOID.EZ are examples.







                                       58




                              Using Multiple Sources

        Some precautions must be taken when using multiple sources in an
        antenna. The phase of resulting currents can be 180 degrees from
        where you intended. This can be prevented in phased arrays of
        parallel wires by making sure that end 1 of the wires are all
        facing the same direction (for example, all wire end 1's of a
        vertical array connected to ground). Reversing a wire will
        reverse the effective polarity of all sources in that wire. An
        ambiguity can arise when placing a split source at a wire
        junction because the polarity can depend on which wire the source
        "belongs" to and which way this wire is facing. A source is
        always placed so the positive terminal (or terminal of outward-
        flowing current) faces end 2 of the wire in which it's placed. A
        split source placed on a junction of two wires "belongs" to the
        wire specified as its desired position. Therefore, it will be
        placed with the positive terminal facing end 2 of the specified
        wire. Ambiguity can be avoided by making the wires face the same
        direction by connecting them end 1-to-end 2. Whenever you use
        multiple sources in any antenna other than simple, parallel
        wires, it's highly recommended that you look at the currents in
        the wires and make sure they're really flowing in the direction
        you thought. See "Currents" under INTERPRETING THE RESULTS, p.
        65.


                             USING TRANSMISSION LINES

        There are important differences between the NEC transmission line
        models used by EZNEC and real-life transmission lines, so there
        are several things you have to be aware of in order to use them
        effectively.

        First, the EZNEC transmission line models are lossless. They have
        no attenuation and are not accurate models for lines with
        significant loss.

        Second, the only parts of the transmission line model which exist
        as far as the program is concerned are the ends. Imagine the
        model as being two sets of portable terminals which can be placed
        on any two segments. The current and voltage at one set of
        terminals relative to the other is just the same as though there
        were a transmission line connected between them. But the
        transmission line can be any length you specify, including longer
        or shorter than the physical distance between the "terminals".
        Although the terminals are accessible to connect to the antenna
        wires, the transmission line itself is "somewhere else". So,
        unlike real transmission lines, EZNEC transmission line models
        don't interact with the antenna fields. That is, the currents in
        the model's two conductors are always equal and opposite, so the


                                       59




        line doesn't radiate or have current induced by coupling. In many
        real-life cases, a transmission line does interact with the
        antenna fields, and becomes a radiating part of the antenna. This
        can be caused by coupling to the antenna due to non-symmetrical
        placement of the feedline, or by presenting the feedline with an
        unbalanced source or load. EZNEC transmission line models are
        suitable for modeling symmetrically-placed balanced lines such as
        a log-periodic feed distribution line or W8JK phasing line. They
        aren't suitable for modeling, for example, a quarter-wavelength
        phasing stub extending outward from a collinear antenna, since
        the stub wires in a real collinear antenna will have unbalanced
        currents and will radiate. Coaxial lines laid on the ground, such
        as in a vertical phased array feed system, may carry current on
        the outside just like a ground radial wire. In many cases this
        can be ignored and the EZNEC model used. A coaxial cable with
        field interaction (that is, with current flowing on the outside
        of the shield) can be modeled with a combination of a wire and
        transmission line model as described later in this section. A
        two-wire line which interacts with the antenna's fields has to be
        modeled as two wires.

        The third thing to realize about EZNEC's transmission line models
        is that both ends must be connected to wires. If you want to
        connect a source directly to a transmission line, you have to
        create a wire and connect both the source and transmission line
        to it. The wire can be very short and, if desired, very far away
        (remember, the distance between end terminals can be much greater
        than the length of the "transmission line" connecting them), to
        prevent coupling from the antenna. It may be more convenient,
        however, to put the extra wire in the general vicinity of the
        antenna so you can see the transmission lines better with View
        Antenna.  

        Fourth, when a transmission line is connected to the same segment
        as a source or load, it's important  to be aware of the way
        they're connected together. A transmission line is connected in
        parallel with a source or other transmission line, and in series
        with a load, in the same segment.

        Connection is sensitive to wire direction. If two vertical
        elements are defined with one having end 1 grounded and the other
        end 2 grounded, transmission lines connected to them from the
        same point would result in reversed signals to the two antennas.
        Imagine each end of a transmission line having two terminals, "a"
        and "b". If normally connected (not reverse-connected), and if
        terminal "a" of one end is closer to end 1 of its wire, terminal
        "a" of the other end will be closer to end 1 of its wire also.

        A coaxial cable can be modeled quite well with a combination of
        transmission line model and a wire. The transmission line model


                                       60




        represents the inside of the coax, and the wire represents the
        outside of the shield. The wire is the diameter of the shield,
        and connected where the shield of the actual cable is. It should
        follow the same physical path as the real coaxial cable. One of
        the example files (DIPTL.EZ) shows how this is done. I don't know
        of any way to accurately model common-mode effects on a two-wire
        transmission line. If it's necessary to do this, the line will
        have to be modeled as two wires.

        Two examples of phased array antennas using transmission-line
        feed are included on the distribution disk.


                         NEAR FIELD / FAR FIELD ANALYSIS

        EZNEC "Near Field" analysis is really a misnomer, but this
        designation was adopted because of its widespread use in other
        modeling programs. It would more accurately be termed "Total
        Field" analysis, because the results include all field components
        and are valid regardless of the distance from the antenna. Near
        Field analysis can and should be used whenever absolute field
        strength (in V/m or A/m) is needed.

        When setting up a Near Field analysis (using Main Menu selection
        'NS'), the only caution is to avoid if possible having steps
        occur inside wires. If this happens, the results for those steps
        won't be of practical use, and one of them may be reported as the
        field maximum. See "The Near Field Setup Menu", p. 115, and "Near
        Field" (INTERPRETING THE RESULTS), p. 63, for more information.

        The nature of the field close to an antenna is different than it
        is far from an antenna, so the regions surrounding an antenna can
        conveniently be separated into a "near field" and "far field".
        Most amateurs have dealt primarily with far field phenomena. In
        the far field:

            - The flow of energy is radially outward from the antenna.
            - The electric and magnetic field strengths fall off as 1/r,
              where r is the distance from the antenna.
            - The power density falls off as 1/r^2.
            - The ratio of E (electric) to H (magnetic) field is 377
              ohms.
            - The radiation pattern does not change with distance.
            - The vector product of the E and H fields, EXH, is purely
              real.

        None of these is true in the near field. In the near field, some
        energy (in some cases, a great deal of energy) is stored and
        moved without being radiated. The ratio of E to H field depends
        on the type of antenna, being for example, high for a short


                                       61




        dipole and low for a small loop. The H field has components that
        fall off as both 1/r and 1/r^2; the E field has components that
        fall off as 1/r, 1/r^2, and 1/r^3. Therefore, the assumptions
        made for far field analysis (which EZNEC uses to generate
        patterns and the far field table) are not valid near the antenna.

        How far from the antenna do the far field assumptions become
        valid? The exact answer is "infinitely far". But the practical
        answer is much, much closer. The boundary between near and far
        fields is generally defined as 2L^2/lambda, where L is the
        longest dimension of the antenna and lambda is the wavelength. So
        for a half wavelength antenna, the boundary is a half wavelength.
        The distance at which the field takes on the characteristics of
        the far field depends on the nature of the antenna and the
        accuracy desired. For an electrically short dipole (much less
        than 1/2 wavelength), the 1/r, 1/r^2, and 1/r^3 electric field
        terms are all equal at a distance of about 1/6 (actually
        1/(2*pi)) wavelength. The relative contributions of the higher-
        order terms of course decreases rapidly beyond that distance.

        For far field analysis, separate figures for E and H field gain
        or strength aren't necessary, because their ratio is the same in
        the far field for all antennas. Observation distance makes no
        difference to the antenna pattern, so an arbitrarily long
        distance is chosen. (EZNEC does give far-field intensity in mV/m
        at 1 km or 1 mile for 1 kW power input as an option for its
        tabular far field output -- see "The Options Menu", p. 82. This
        unit of measure is commonly used by the broadcast industry.)

        In summary, near field analysis should be used when the distance
        from the antenna is on the order of a wavelength or less. Beyond
        that distance, far field analysis can be used if desired.
        However, except for mV/m at 1 km or mile for 1 kW, EZNEC doesn't
        report far field strengths in V/m or A/m. Because Near Field
        analysis is valid at any distance, it should be used when field
        strength in V/m or A/m is required.

        Remember that many factors affect the results from a modeling
        program. EZNEC should not, under any circumstances, be used to
        determine whether the energy or field strength from an antenna
        presents a hazard or unsafe condition. This applies to all
        results, including both Far Field and Near Field. See the
        DISCLAIMER beginning on p. 9.









                                       62




                             INTERPRETING THE RESULTS

                                     Patterns

        EZNEC provides plots or tabular data of far field sky wave
        analysis. Field strength is given in dBi, or relative to a
        reference of the user's choice. Near field data are furnished in
        tabular form only.

        Three choices of far field plot are available, azimuth,
        elevation, and three-dimensional (3D). Any elevation angle can be
        chosen for azimuth plots, and any azimuth angle for elevation
        plots. 2D Plot range can be restricted if desired. EZNEC includes
        a visualization aid for orienting the pattern relative to the
        antenna, in the View Antenna display, where the 2D pattern plot
        or a "slice" of the 3D plot can be superimposed on the
        representation of the antenna. More information about these
        features can be found under "The 3D Pattern Plot Display and
        Menu", p. 104, and "The SWR Graph Display and Menu", p. 114.

        Because the far field sky wave from a horizontally polarized
        source is zero at a zero elevation angle for any ground type, and
        a vertically polarized source produces zero sky wave for any
        finite-conductivity ground, attempts to calculate a 2D pattern
        under these conditions will result in an error message.

        The Analyze feature gives a quick summary of key pattern
        characteristics, such as beamwidth and front/back ratio.

        EZNEC offers an alternate azimuth coordinate choice, "bearing".
        This presents azimuth angles in degrees clockwise from the +y
        axis, to correspond to compass bearing. The choice is made in the
        Options Menu. No change to the plot orientation occurs when
        changing between standard and bearing representations.

                                    Near Field

        Unlike far fields, the near fields can be pointed in any
        direction. They are broken into three components, in the X, Y,
        and Z directions. A total is also shown. The total is generally
        all that will be used unless you have an interest in the
        orientation of the E or H field. EZNEC also reports, near the top
        of the list, the largest field that was found. Be careful that
        none of the steps falls inside a wire; if it does, the results
        for that step won't be meaningful, and it could be reported as
        the maximum value.

        Because the ratio of E (electric) to H (magnetic) near field
        depends on the antenna type and the distance from it, the two
        fields must be analyzed separately.


                                       63




        Note that "Near Field" analysis actually reports the total field,
        so it's valid at any distance, including far from the antenna.
        For more information, see "The Near Field Setup Menu", p. 115,
        and NEAR FIELD / FAR FIELD ANALYSIS, p. 61.

        Remember that many factors affect the results from a modeling
        program. EZNEC should not, under any circumstances, be used to
        determine whether the energy or field strength from an antenna
        presents a hazard or unsafe condition. This applies to all
        results, including both Far Field and Near Field. See the
        DISCLAIMER beginning on p. 9.

                       Source (Feedpoint) Impedance and SWR

        The impedance, SWR, voltage, and current at each source can be
        viewed or printed by selecting 'SD' (Source Data) from the Main
        Menu. In addition, a graph of the SWR vs. frequency can be
        displayed by pressing 'SW'. If EZNEC reports a very low value of
        resistance at any source, be careful -- this might indicate
        operation beyond EZNEC's limits. If two elements are closely
        spaced and fed out of phase (W8JK-type antennas), the low
        resistance is real but the real antenna might not work like EZNEC
        predicts unless you have included wire loss (a Main Menu choice).
        Losses become important when the resistance is low, so be sure
        wire loss is included if a low resistance is indicated. Negative
        resistances sometimes are reported for multi-element arrays.
        These actually can occur but are subject to the same cautions as
        low positive resistances. (The SWR for these sources will be
        reported as "undefined", and shown on the graph as infinite.) A
        negative source resistance where only one source is used is
        positive indication of operation of EZNEC beyond its
        capabilities. Very small loops will cause this condition, as will
        overlapping wires or wires occupying the same space. These
        conditions are not detected by EZNEC's Guideline Check.

        The SWR shown is the SWR which would be present on a feedline
        connected in place of the source. Values are given for 50 ohm and
        user-specified feedline impedances. (The user-specified impedance
        is selected with choice 'SZ' in the Main Menu.) The SWR is
        directly calculated from the source impedance. If a source is
        connected to a transmission line model and you want to know the
        SWR on the transmission line, the SWR reference impedance must
        match the characteristic impedance of the transmission line.









                                       64




                                     Currents

        The currents at each segment can be displayed with the View
        Antenna feature ('VA' from the Main Menu or 'V' from the Wires
        Menu) or seen in tabular form by selecting 'CU' from the Main
        Menu. The currents give important information about antenna
        operation. In addition, they're invaluable in assessing whether
        the antenna is working as intended and in spotting conditions
        where EZNEC is being used beyond its capabilities. Note that the
        View Antenna display is intended as a visual aid. Although the
        overall display is correct, it has been smoothed so that details
        about the current along a single segment or at the junction of
        two segments may not be precise. If you need this level of
        detail, refer to the tabular data.

        One thing to look for is symmetry. If the antenna is symmetrical,
        the currents should be also. If not, some error has been made in
        wire definition, source placement, or some other area. For
        example, the current from the vertical part of a ground plane
        antenna should split evenly among the radials if the radials are
        the same length and evenly spaced. Make it a habit to look for
        these symmetries and you'll spot problems before bad results lead
        you astray.

        Positive current is defined as flow of positive charge from end 1
        to end 2 of a wire.

        Another thing to look for is abrupt and unexplained current
        changes (instead of a smooth change from one segment to the
        next). This usually is due to not having enough segments but may
        be due to some other factor causing EZNEC to be operating beyond
        its limits. Sudden current reversals may be no cause for concern
        as they might be due to the way the wires have been defined.
        Positive current flow always is defined as being from end 1 to
        end 2, so if two end 1's or two end 2's are connected together, a
        180-degree shift in current direction will be indicated at the
        junction of the wires (provided View Antenna phase information is
        on or you are looking at the currents in tabular form). The
        current actually is continuous as it should be, but the
        definition of direction changes from one wire to the other.
        There's nothing wrong with connecting wires in this fashion but
        don't be confused by the currents EZNEC shows as a result. Watch
        for this also when using multiple sources -- see "Using Multiple
        Sources", p. 59.

        Current phase information can be included on the View Antenna
        display, but it frequently conceals important information about
        what's happening to the magnitude of the currents. See "The View
        Antenna Display and Menu", p. 106, for more information about
        this feature.


                                       65




        The importance of currents is underscored by the fact that the
        field generated by a wire is proportional to the current flowing
        on it. If one element of a multi-element antenna shows a small
        current relative to the others, it's not contributing much to the
        overall field. It may, however, be generating just enough to
        deepen a null in the pattern. If your model contains several
        nearby wires, towers, and other objects, a look at the currents
        on them will quickly tell you whether they're having a
        significant effect on your antenna's performance. If the current
        on an object is small relative to the current on your antenna,
        you generally can remove it from the model without much impact on
        the result (unless deep nulls are important; even small fields
        can have a significant effect on nulls). Shorter conductors
        require more current than long ones to have the same effect.

                                    Load Data

        Load data are shown by typing 'LD' at the Main Menu. The voltage
        across, current through, impedance of, and power loss of each
        load is shown. In addition, the total load loss is shown in watts
        and dB. The loss figures are invaluable in determining the loss
        caused by traps, loading coils, and the like. You can also
        determine the voltage across the load or current through it under
        actual operating conditions by entering, from the Options Menu,
        the power to the antenna.


                                       TIPS

                    Doubling the Number of Available Segments

        EZNEC is capable of modeling very complex antennas. However, its
        segment capability can be effectively doubled in some cases. The
        requirements are that the antenna (including sources and loads)
        is symmetrical, and that only free-space analysis is desired. If
        these are true, one-half the antenna can be modeled over a
        perfect ground, and the result will be the same as the whole
        antenna modeled in free space. (Note, however, that the reported
        gain will be 3 dB higher, since all the antenna's power is
        concentrated in one hemisphere.) A simple example of this
        principle is a quarter-wavelength vertical over a ground plane,
        which has the same pattern as a free-space dipole. NEC's symmetry
        capability is not implemented in EZNEC.









                                       66




                             Segment Length Tapering

        Note: The process of making an element from telescoping tubing is
        called "tapering" by some authors, and corrections for NEC-2's
        inaccuracy in modeling these is sometimes called "taper
        correction". EZNEC uses the term "segment length tapering" or
        "segment tapering" to refer to the process of tapering segment
        lengths, rather than diameters. (The process of correcting NEC-2
        for steps in wire diameter is called "stepped-diameter
        correction".)

        Multiple wires joining at an acute angle must sometimes have
        shorter segments than single straight wires or wires joining in a
        line, particularly when a source or load is near the junction.
        This is seen with antennas such as multiple dipoles connected to
        a common feedpoint. Another case is with very low elevated radial
        systems (see p. 48). The straightforward solution in this
        situation is to increase the number of segments. However, doing
        so increases computation time. The technique described here
        provides high accuracy with a smaller total number of segments.

        Instead of making the entire wires out of short segments, the
        segments can be made short near the junction, increasing, or
        "tapering", to a greater length away from the junction. EZNEC
        automates this process but it's useful to know how the procedure
        works so you can optimize it for your particular purpose. The
        basic procedure is to replace the original wire with several
        wires of different lengths. The new wire closest to the junction
        is made very short and with one segment. The second wire is made
        twice the length of the first, also with one segment. This
        process is continued until the segment length becomes long enough
        (say, 1/20 wavelength), and the remainder of the original wire is
        made up of a multiple-segment wire of approximately this segment
        length. In the automated process, you can choose the minimum and
        maximum segment lengths or use the default values of 1/400 and
        1/25 wavelength. More information can be found on p. 91.

        NOTE that this technique shouldn't generally be used if
        connecting wires have different diameters. See "Wires With
        Different Diameters", p. 51.

                                     Scaling

        The antenna can be easily scaled for another frequency. Simply
        precede a new frequency with the letter 'r' when changing the
        frequency via the Main Menu (selection 'FR'). This will scale the
        antenna so that the wire end coordinates (including scaling of
        height above ground) and media height and boundaries remain the
        same in terms of wavelength at the new frequency. Wire diameters
        will be scaled only if they aren't specified as wire gauge, and


                                       67




        transmission line lengths only if they are not specified in
        degrees. Transmission line Z0 isn't modified, even if it was
        originally entered as wire diameter and spacing. Wire and ground
        conductivity aren't scaled by this process; see "Conductivity and
        Scaling", below.

                             Conductivity and Scaling

        If you're modeling your antenna over "real" ground at other than
        the actual frequency of use, the ground conductivity and wire
        loss (as well as wire and radial length and diameter) must be
        scaled for accurate results. The conductivity of the ground or
        wire should be changed in direct proportion to the frequency. For
        example, if the actual antenna operates at a frequency of 7 MHz
        over ground with .001 S/m conductivity, it can be accurately
        modeled at 299.8 MHz if the ground conductivity is changed to
        299.8 / 7 * .001 S/m. Dielectric constant should not be scaled.
        Failure to correctly scale ground conductivity generally will
        affect field strength only at very low elevation angles.

                                 Using Templates

        It's usually faster to make modifications to an existing antenna
        than to describe one from scratch. Save some typical examples of
        the types of antennas you frequently model and recall them as
        starting points when you want to design a new antenna of the same
        general type.

                           Modeling Complex Structures

        One project undertaken by the author was modeling a group of
        towers, each having a top hat. First, a fairly elaborate model of
        a single tower was constructed. Next, a single, large diameter
        wire of the same height was modeled, adjusting the diameter to
        obtain the same impedance as the tower (the height needed only
        slight adjustment). This simpler tower model was used for the
        remaining steps. A fairly elaborate top hat model was placed on
        the simplified tower and analyzed. Then the top hat was
        simplified as much as possible while retaining approximately the
        correct impedance at the tower feedpoint (a good example of the
        usefulness of EZNEC's Delete Wires function). Finally, the group
        of towers was modeled, using the simplified models. This approach
        can be taken for a variety of complex structures.









                                       68




                                   WHY NOT DBD?

        It makes sense to compare an antenna's gain with the gain of a
        known, real antenna. After all, the "isotropic radiator" doesn't
        exist. A dipole is a common and convenient reference. So why not
        use the gain of a dipole as a reference? When a dipole is used as
        a reference, the gain is measured in "dBd", or decibels gain
        relative to a dipole. (Similarly, the universally accepted
        standard "dBi" is decibels gain relative to an isotropic source -
        - one which truly radiates equally [poorly] in all directions).
        To use either term, a reference field must be established. That
        is, we need to know the field strength that an isotropic source
        or dipole would produce for the same power input as the antenna
        we're comparing. The isotropic antenna has the great advantage of
        being theoretical -- since it doesn't exist anyway, we can
        precisely define its field strength under theoretical conditions.
        This makes it constant and not subject to ground, orientation, or
        any real considerations. But what's the gain of a dipole? Well,
        the gain of an infinitely thin, half-wavelength dipole in free
        space is 2.15 dBi. But that's no more "real" an antenna than the
        isotropic radiator!  The danger in using 2.15 dBi as 0 "dBd" is
        that it's easy to get the impression that it represents the gain
        of A real dipole. It does not!  To see just how bad an error this
        would represent, note that the gain of the "back yard dipole"
        modeled in TEST DRIVE has a gain of 6.8 dBi (or +4.65 "dBd") --
        just by putting the dipole in the back yard, we've picked up more
        than 4 dB gain "relative to a dipole"! (One of the factors
        increasing the gain of a dipole over ground is that all its power
        is concentrated in one hemisphere -- above ground -- while the
        isotropic radiator and free-space dipole spread power over both.)
        For these reasons, EZNEC uses the universally accepted and
        unambiguous standard: dBi. EZNEC permits you to enter any other
        reference of your choosing, but it's highly recommended that you
        use it for comparison between models of real antennas. Decide
        what reference antenna to use and model it. Find the gain at the
        elevation and azimuth angles of interest and use that as a
        reference to compare other antennas against.















                                       69


























                                      EZNEC








                                 REFERENCE MANUAL




                       GENERAL INFORMATION AND CONVENTIONS

        No distinction is made between uppercase and lowercase letters.

        Scientific notation may be used for any numerical input if
        desired (e.g., '7.15E6' = 7,150,000; '4E-3' = 0.004; '.123E2' =
        12.3). 

        Because of size restrictions, a limited number of significant
        digits can be shown in some menus. If fewer significant digits
        show than you had entered, the program is still using the full-
        precision number (up to seven significant digits) for
        calculations; the shortening only affects the display.

        Pressing <Enter> isn't necessary following entries requiring a
        single keystroke. When the number of wires, sources, or loads
        exceeds 9, the program requires <Enter> following entry of the
        number; if the total number is 9 or fewer, it doesn't. Keystrokes
        made while EZNEC is busy printing, calculating, or plotting are
        not remembered. This is intentional to prevent you from having,
        say, a plot which disappears as soon as it's complete due to an
        accidental keystroke entered during the calculating/plotting
        process. (Exception: <ESC>, entered while calculations are in
        process, will end the calculations and return you to the Main
        Menu. A message to this effect appears at the bottom of the
        screen during calculation.)

        In the Wires, Sources, Loads, Transmission Lines, and Media
        Menus, the item which is highlighted can be changed by using the
        arrow keys and the <PgUp> and <PgDn> keys. If the number of items
        exceeds the number which can be shown on screen at one time,
        these same keys scroll the display. After entering the desired
        value, the entry can be terminated using any of the above keys or
        <Enter>. <ESC> also will terminate the entry but the value you
        entered won't be saved.

        During the calculations, text and a graph appear which show
        EZNEC's progress. The portion of the "thermometer" which is
        filled is only an approximation of the percentage of completion.
        Uneven calculation speeds are normal, particularly when the disk
        is being used as virtual RAM.

        Following are some illustrations of the coordinate system. A
        standard right-handed system is used. Azimuth angles begin at the
        +x axis and increase counter-clockwise in the XY plane. Elevation
        angles begin at the +x axis and increase counter-clockwise in the
        XZ plane.

        It's helpful to envision the antenna as you see it in the
        elevation plots: the +x axis is to the right, the +y axis is into


                                       71




        the screen, and the +z axis is up. Use the View Antenna or 3D
        plot feature and look at some of the example antennas and
        patterns to help you become familiar with the coordinate system.


                                   +z                                     
           
                                    |           
                                    |         
                                    |       
                                    |      
                                    |   
                    -x _____________|______________ +x
                                    |      
                                    |      
                                    |      
                                    |      
                                    |      
                                    |      
                                   -z      

            As seen in elevation plots (+y is into the screen away from
            you)


        In azimuth plots you're viewing from the top of the antenna, so
        +x is to the right, +y is up, and +z is out of the screen:


                                   +y                                     
           
                                    |           
                                    |         
                                    |       
                                    |     
                                    |   
                    -x _____________|______________ +x
                                    |
                                    |
                                    |           
                                    |         
                                    |       
                                    |     
                                   -y

            As seen in azimuth plots (+z is out of the screen toward you)


        EZNEC gives you two choices (via the Options Menu) for measuring
        azimuth angles, called "azimuth" and "bearing". Azimuth angles


                                       72




        are measured in the conventional mathematical sense --
        counterclockwise from the +x axis: the +x axis is zero degrees,
        the +y axis 90 degrees azimuth. If you choose compass bearing,
        "north" is up on an azimuth plot, and bearings are measured
        clockwise from the +y axis (top of screen). Changing from one
        method to the other doesn't change the pattern, antenna
        orientation, or axes; it only changes the numerical angles which
        are reported.

        Elevation angles are measured upward from the horizon in the XZ
        plane. The XY plane is zero degrees elevation, the +z axis 90
        degrees elevation.

        In general, the largest numbers permitted are about +/- 1E37, and
        the smallest non-zero values +/- 1E-37. If the value being
        requested is an integer (for example, the number of wire
        segments), the largest values are about +/- 32,000. Because these
        values greatly exceed any normally-required input data, EZNEC
        doesn't routinely check to see if numbers entered are within
        these ranges. If they are not, the program will crash.


                                    SCROLLING

        Many displays are too large to show on a single screen. When this
        occurs, different parts of the display can be accessed by
        scrolling. Use the up and down arrow keys to move the displayed
        area in the indicated direction. <PgUp> and <PgDn> will move the
        displayed area up or down a full screen. <Ctrl>-<Home> and
        <Ctrl>-<End> will move to the beginning and end of the display,
        respectively. If the display is wider than the screen, horizontal
        scrolling can be done with the left and right arrow keys, <Home>,
        and <End>.


                                   LIMITATIONS

        All EZNEC arrays are dynamically allocated, so there is no fixed
        limit of the number of wires, sources, loads, or transmission
        lines. The number of segments is limited to 500. If the amount of
        available conventional RAM (lowest 640k) is unusually small,
        EZNEC's capability may be reduced. Most DOS systems are able to
        make at least 600k of conventional memory available, which is
        more than adequate for any model. Techniques to increase the
        amount of available conventional memory include unloading
        unneeded drivers or memory resident programs, or loading them
        into the high memory area by using HIMEM.SYS (see DOS
        documentation for details) or memory manager software such as
        QEMM386. The amount of available conventional memory can be
        determined by entering 'MEM' at the DOS prompt.


                                       73




        Between 2 and 3 MB of available extended memory is required to
        run EZNEC. If less than this amount is available, you will see an
        error message and EZNEC will refuse to run. The disk will be used
        as necessary as virtual memory if insufficient extended memory
        isn't available for calculations.


                                    THE MENUS

        Displays which are larger than the screen can be viewed by use of
        scrolling. See SCROLLING, p. 73.

                                  The Main Menu

        The Main Menu is the gateway for all program operations. From it,
        you can save or recall antenna descriptions, change the antenna
        description and how the plot is done, or do any other program
        function. Note the cursor near the lower right corner of the
        screen. The first letter you type will be shown. The second
        letter will terminate the entry, begin the desired action, and
        erase the letters in the corner. If you type an unrecognized
        combination, the program will erase them so you can start over.
        Press <Esc> to return to the Main Menu from any sub-menu. Many
        options are unavailable, and a few are different, when the
        program is started in TraceView mode. See TRACEVIEW, p. 126, for
        more information about using TraceView. Following is a
        description of each Main Menu selection and its operation.

        TI -- TITLE

        The title can contain up to 30 characters and may be any
        combination of letters, numbers, symbols, punctuation, and
        spaces. The title appears at the top of printed outputs.

        FR -- FREQUENCY

        Frequency is entered in MHz. The corresponding wavelength in
        current units is shown beside the frequency. If you enter '0',
        the frequency will be set to 299.7925 MHz, the frequency at which
        the wavelength is one meter. At this frequency, dimensions and
        coordinates entered in meters will also be in wavelengths. If you
        change the frequency when units are wavelengths, you can choose
        to have the antenna stay the same physical size (and change size
        in terms of wavelengths) by selecting 'p' or to stay the same
        size in wavelengths (and change physical size) by selecting 'w'.
        If the latter choice is made, the antenna will be rescaled in the
        same manner as described in the next paragraph.

        An antenna can easily be rescaled by preceding the new frequency
        with 'r'. The items which will be rescaled are  wire end


                                       74




        coordinates, wire diameter if not specified as wire gauge, second
        medium height, second medium boundary, and transmission line
        lengths if not specified in degrees. (Transmission line Z0 isn't
        modified even if it was initially entered as wire diameter and
        spacing.)

        The FREQUENCY column shows SWEEP when Frequency Sweep is on.

        WI -- WIRES

        Making this selection will bring up the Wires Menu, described
        below.

        SO -- SOURCES

        Making this selection will bring up the Sources Menu, described
        below.

        LO -- LOADS

        Making this selection will bring up the Loads Menu, described
        below.

        TL -- TRANSMISSION LINES

        Making this selection will bring up the Transmission Lines Menu,
        described below.

        GT -- GND TYPE

        Choose this to select perfect ground, real ground, or free space.
        If you choose Real ground, you'll get a choice of (F)ast, (H)igh
        accuracy, or (M)ININEC. See MODELING GROUND on p. 54 for
        information about choosing the ground type.

        GD -- REAL GND DESCRIPTION

        If real ground has been selected (GND TYPE, above), this
        selection will bring up the Media Menu, described below. If the
        ground type is perfect ground or free space, this selection won't
        appear.

        WL -- WIRE LOSS

        This selection permits you to model the effect of wire loss.
        EZNEC calculates the skin effect loss at the chosen frequency and
        inserts it into the model. The loss characteristic is applied to
        all conductors in the model. You can choose the built-in
        resistivities of aluminum alloy or copper, or enter the
        resistivity and relative permeability of any other material.


                                       75




        (Note: Pure aluminum is seldom encountered in antenna work, and
        the resistivity of alloys varies considerably. The built-in value
        is for 6061-T6 alloy, commonly used for antennas.) If the antenna
        is made of more than one material, choose the material of the
        smallest-diameter conductors or those carrying the most current.
        With plated wires enter the parameters of the outermost material.
        Wire loss can have a major impact on the performance of small or
        short antennas. Always do an analysis including wire loss if a
        lossless antenna has gain that seems too good to be true (because
        it probably is!)

        UN -- UNITS

        You can choose feet, inches, meters, millimeters, or wavelengths
        as the units of measurement. Note: When feet are chosen, wire
        diameter is in inches; when meters are chosen, wire diameter is
        in millimeters. Headings and prompts tell you this fact but it's
        easy to overlook. When wavelengths are chosen, you can choose
        another unit for diameters.

        PT -- PLOT TYPE

        Entering 'PT' will allow you to choose Elevation of Azimuth
        plots, which are two dimensional (2D), or a three-dimensional
        (3D) plot. See "The 2D Pattern Plot Display and Menu", p. 101,
        and "The 3D Pattern Plot Display and Menu", p. 104, for more
        information.

        PA -- AZIMUTH or ELEVATION ANGLE

        This selection, which chooses the angle for far field plots, is
        not available when 3D Plot Type has been selected with choice
        'PT'. As an example of its operation, to see what the far field
        azimuth pattern of your array looks like at an angle 20 degrees
        above the horizon, choose AZIMUTH with selection PT, and 20 for
        selection PA. (See "Patterns", p. 63, for a more detailed
        description of the plots.) If you switch back and forth between
        Azimuth and Elevation plots, the angle for each is remembered and
        recalled when you return.

        PR -- PLOT/TABLE RANGE

        This choice isn't available when a 3D Plot Type has been
        selected. To choose a table or 2D plot range of 360 degrees or
        180 degrees (elevation plots with ground plane), enter 'F' (for
        Full range) when prompted. Or you can save some calculation time
        by restricting the angles to a region of interest. Step size
        (selection 'SS') must always be positive but you can obtain any
        portion of the plot desired by putting the upper and lower limits
        in the correct order. For example (assuming step size = 5), lower


                                       76




        limit = 10 and upper limit = 190 will plot 10, 15, 20, . . .,185,
        190 degrees. Lower limit = 190 and upper limit = 10 will plot
        190, 195, 200,. . .355, 0, 5, 10 degrees.

        SS -- STEP SIZE

        This determines the spacing between points on the plot or table.
        Since the far field (pattern) is calculated for each point, far
        field calculation and plotting time will vary with step size. For
        general purpose 2D (azimuth or elevation Plot Type) plotting, 1
        or 2 degree step size is recommended, with smaller sizes if the
        pattern has extremely sharp lobes. For 3D (3D Plot Type) plots, 2
        degrees is the minimum step size, and this creates too dense a
        pattern for general use. 5 to 10 degrees is more useful for a 3D
        display. Step size must be positive. The minimum for 2D plots is
        0.1 degree. Both the 2D and 3D selections are saved with the
        antenna file.

        OR -- OUTER RING OF PLOT

        If you enter 'A' for automatic scaling, the outer ring of the 2D
        plot grid will equal the greatest value of any of the displayed
        plots. The outer ring value can be fixed at any other value if
        desired.

        RF -- REFERENCE

        If zero is chosen all plots, tables, etc. will be in dBi. The
        REFERENCE value is useful if you want to use some other standard
        of comparison such as a reference antenna.

        SZ -- SWR Z0

        Source data and the SWR Graph include SWR for each source. This
        is the SWR which would appear if the source were connected to the
        antenna through a transmission line of a specific impedance. SWR
        values for a line impedance of 50 ohms is always given, along
        with a second impedance you can choose with this selection. The
        alternate Z0 is useful if you want to feed an antenna with a line
        of other than 50 ohm impedance and want to know the SWR which
        will result, or if you connect a source to a transmission line
        model and want to know the SWR on the line. If you connect a
        source to a transmission line model and want to know the SWR on
        the transmission line, set this parameter to the Z0 of the
        transmission line (or use the 50 ohm SWR value if the Z0 is 50
        ohms). The SWR on the transmission line is then the SWR reported
        for the source.





                                       77




        FI -- FIELD(S) TO PLOT

        You can choose to plot (in 2D only) the horizontally polarized,
        vertically polarized, and total fields with separate traces if
        desired.

                      --------------------------------------

        BRowse file

        This selection allows you to view any ASCII text file. It's
        particularly useful to view a Frequency Sweep output, to look at
        files containing data saved to files such as currents or source
        data. See SAVING, RECALLING, AND DELETING FILES, p. 123, for
        information about entering a file name.

        DElete, REcall, SAve desc

        These are used to delete, recall, combine, and save antenna
        descriptions. (Combining is done via the recall operation.) You
        can specify any name and path/directory to save or recall files,
        but there are restrictions on the extension. If not specified,
        EZNEC will assume the directory specified by the Options Menu,
        and the extension ".EZ". See SAVING, RECALLING, AND DELETING
        FILES, p. 123; and  SAVING, RECALLING, COMBINING, AND DELETING
        ANTENNA DESCRIPTIONS, p. 123, for more information.

        show MEmory

        This selection shows you the amount of conventional (lower 640k)
        and extended (XMS) memory available. The second line of the
        display shows the smallest amount of conventional memory which
        was available since the program was started.

        ANalyze

        ANALYZE calculates and shows forward gain, angle of forward gain,
        front/back or front/side ratio, beamwidth, 3-db beam angles,
        major sidelobe level, major sidelobe angle, and front/sidelobe
        ratio. These are presented in tabular form. For saving to a file,
        see SAVING, RECALLING, AND DELETING FILES, p. 123. ANALYZE cannot
        be done before a plot or table has been done; if you try, a
        message will appear. ANALYZE also can be run while the plot is on
        the screen by typing 'A' according to the prompt at the upper
        right corner of the plot (see "The 2D Pattern Plot Display and
        Menu", p. 101). If this is done, ANALYZE results will appear with
        the plot, along with lines on the plot which show you exactly
        what ANALYZE found. ANALYZE regards the second-largest lobe to be
        the "sidelobe" for calculation purposes. If the front/back ratio
        is unity (zero dB), ANALYZE will calculate the gain at an angle


                                       78




        of 90 degrees from the maximum direction and report the
        front/side ratio instead. 

        CUrrents

        Prints (to the screen, printer, or file) a list of currents at
        each segment. This is useful to observe the current distribution
        on an antenna and to check for problems with the description or
        those caused by specifying too few segments (see "Currents" in
        INTERPRETING THE RESULTS, p. 65). For saving to a file, see
        SAVING, RECALLING, AND DELETING FILES, p. 123.

        Load Data

        Prints (to the screen, printer, or file) the impedance, voltage,
        current, and power consumption of each load. This can be very
        useful and enlightening when analyzing trapped or loaded antennas
        (see USING LOADS, p. 56). If two identical loads are on segments
        adjacent to a junction of two wires, the parameters of the
        combination will be shown, as well as those of the individual
        loads. This allows you to simulate a load at a wire junction. For
        saving to a file, see SAVING, RECALLING, AND DELETING FILES, p.
        123.

        Nr Fld

        This selection begins Near Field calculation. Results from near
        field calculation are displayed in tabular form. See selection NS
        (Nr fld Setup) for more information.

        Src Data

        Prints (to the screen, printer, or file) a list of the voltage,
        current, impedance, power, and SWR (relative to 50-ohm and user-
        defined impedance systems) at each source. With antennas having
        multiple sources, a legitimate negative resistance may appear.
        This can happen in reality; in a phased array, it means that
        power is flowing from the element into the feed system. The
        element gets this power from the other elements by means of
        mutual coupling. A negative resistance seen when the antenna has
        only one source indicates operation beyond the capabilities of
        the program. See USING SOURCES, p. 94, and "The Sources Menu", p.
        94. For saving to a file, see SAVING, RECALLING, AND DELETING
        FILES, p. 123.








                                       79




        ffld TAble

        Prints (to the screen, printer, or file) the far-field pattern
        data in tabular form. Several formats are available; see
        selection TU (Table Units) in The Options Menu, which begins on
        p. 82. This selection will initiate a calculation if it hasn't
        yet been done for the current antenna. If a 3D Plot Type has been
        specified, you will be prompted for how to organize the data (as
        azimuth or elevation "slices") and the range of "slices" to
        include.

        <Enter> = Plot

        <Enter> generates a far-field plot (pattern) or, if Frequency
        Sweep is on, initiates a frequency sweep. 

        Freq Sweep setup

        This brings up the Frequency Sweep menu, described beginning on
        p. 116.

        Nr fld Setup

        This brings up the Near Field Setup menu, described beginning on
        p. 115. See "Near Field" (INTERPRETING THE RESULTS) on p. 63 and
        NEAR FIELD / FAR FIELD ANALYSIS on p. 61 for additional
        information about Near Field analysis.

        OPtions menu

        Making this selection will bring up the Options Menu, described
        beginning on p. 82.

        SWR graph

        This initiates the SWR Graph. It functions differently depending
        on whether Frequency Sweep is on or off. If Frequency Sweep is
        off, selecting 'SW' will result in a prompt for a frequency range
        and step size, or frequency list file (see THE FREQUENCY LIST
        FILE, p. 135). After you enter the requested values, EZNEC will
        sweep the desired frequencies and display the SWR Graph. If
        Frequency Sweep in on, this selection will graph the SWR data
        from the last frequency sweep. If Frequency Sweep is on and
        antenna description or frequency sweep limits have been changed
        since the last Frequency Sweep run, or Frequency Sweep hasn't yet
        been run, you'll see the message that the Frequency Sweep must be
        run before displaying the SWR Graph. See "The SWR Graph and
        Menu", p. 114, for additional information.




                                       80




        Guideline Ck

        Activates the Guideline Check process, which checks for segments
        which are too long or short, segment length/diameter ratio out of
        bounds, and wires connected to a non-MININEC real ground. (This
        process is run automatically when a description file is read or
        when wires are changed, unless disabled from the Options Menu.)
        There are two sets of guidelines, conservative and minimum
        recommended. In general, you should keep your antenna within the
        minimum recommended guidelines, and observe the conservative
        guidelines if the antenna is narrowband or critical. When the
        Guideline Check is shown, you can press 'F' (Fix segs) to
        automatically adjust the lengths of all beyond-guideline
        segments. Or you can press 'S' (auto Segs) to adjust the number
        of segments on all wires to the minimum number which will meet
        guidelines. In both cases, you can choose which set of guidelines
        will be followed. For saving the results to a file, see SAVING,
        RECALLING, AND DELETING FILES, p. 123. Caution: Guideline check
        does not find all possible description errors, only the ones
        listed above. Note that some antennas may require more segments
        than the number required to satisfy the Guideline Check (see
        MODELING THE ANTENNA STRUCTURE, p. 45, and CONSIDERATIONS FOR
        MODELING WIRES, p. 47).

        Print Desc

        Prints the antenna description on the printer. This is useful for
        documenting a model and its results. The output may also be sent
        to a file, although not in comma-delimited form.

        View Ant

        Graphically shows you what the antenna looks like. In addition,
        the currents, far-field pattern, and other useful information can
        be superimposed on the antenna diagram. See "The View Antenna
        Display and Menu", p. 106, to learn how to get the most from this
        important display.

        EXit w/o saving

        Normally, the current antenna description is saved in file
        LAST.EZ when the program is exited. If this selection is made,
        the antenna description won't be saved but the program will be
        allowed to terminate even if the current description is
        defective. This is intended as a way of "bailing out" if you've
        made changes which prevent a normal exit. See QUit, below.






                                       81




        QUit

        This is the normal way of exiting EZNEC. When EZNEC is exited,
        the current antenna description is saved in the LAST.EZ file for
        use the next time the program is run. To prevent a defective
        description from being saved, EZNEC might require you to correct
        certain problems before permitting the program to end. If this
        happens and you don't want to correct the problems, use 'EX' to
        exit.


                                 The Options Menu

        The Options Menu is entered by making selection 'OP' at the Main
        Menu. Choices in the Options Menu remain in effect until changed
        or until you end EZNEC. If desired, the changes can be made
        permanent. The choices are read from file ELNEC.CFG each time the
        program is started, and the current choices are stored in
        ELNEC.CFG if you elect to make them permanent.

        EZ -- .EZ FILE PATH

        This selection defines the drive and directory where antenna
        (.EZ) and trace (.PF, .PF3, .G(#)) files will be stored. Although
        you may specify other drives and directories when saving,
        recalling, and deleting files, the drive and directory shown here
        are the defaults used when not otherwise specified. When
        specifying other than the default directory, enter the complete
        path from the root directory.

        TP -- TEMP FILES PATH

        This is the path where temporary files are stored. EZNEC creates
        and erases files each time it runs. For very complex antennas,
        several tens of megabytes of disk space may be required, with
        more being necessary if the disk is used for virtual RAM. If more
        than one drive is available, it is recommended that the drive
        with the most available space be used for temporary file storage.

        OF -- OUTP FILE PATH

        This selection shows the default path for data output files
        written by EZNEC. These include Currents, Source Data, Load Data,
        Pattern Tables, Analysis Data, and Frequency Sweep Data.








                                       82




        MS -- MICSM FILE PATH

        This is the path for MicroSmith files saved during a frequency
        sweep. Normally, you would specify the directory containing the
        MicroSmith program. If you don't have MicroSmith, disregard this
        entry. See MICROSMITH, p. 130, for more information about this
        program.

        GP -- GND DAT FILE PATH

        This is the path where High Accuracy ground data files are
        stored. Files are about 9k bytes each.

        AD -- ABBREV DESC

        If "yes" is chosen, EZNEC will print an abbreviated antenna
        description on the printed output below the plot. ANALYZE
        information is included if ANALYZE has been run.

        GS -- GRID STYLE

        You can choose between the ARRL-style logarithmic-dB scale or a
        40 dB linear-dB scale for the 2D far-field pattern plots.

        PS -- PLOT STYLE

        This affects only the 2D pattern plot. Choices are "standard" and
        "plain/no cursor" style plots. The former includes information
        about the plot (time, date, maximum gain, gain at the cursor
        position, etc.) and the latter doesn't.

        AC -- ANGLE CONVENTION

        This selects the convention used to report azimuth angles. If
        "Compass brng" is chosen, angles are measured clockwise from the
        +y axis (up on the screen when showing azimuth plots). This
        corresponds to the compass bearing with north at the top.
        Otherwise, the convention will be the standard mathematical one
        of angles increasing with counterclockwise rotation from the +x
        axis (to the right on the screen when showing azimuth plots).
        Changing the angle convention doesn't change the axes, pattern,
        or antenna orientation; it only affects the numerical
        presentation of azimuth angles.









                                       83




        FP -- SHOW FS PLOTS

        When plots are being saved during a frequency sweep, you can
        either see each plot as it is calculated, or inhibit the plot
        display until all the plots are calculated. Showing interim plots
        may result in undesired flashing of the monitor as it switches
        between text and graphics modes.

        PQ -- PRINT QUAL

        This selection appears only if a 24-pin dot-matrix printer has
        been specified with EZSETUP. "Draft" causes plot prints with 8-
        pin quality. "High Res." plot prints use all 24 pins for higher
        quality but take longer.

        DG -- DEF GND CONST

        These are the conductivity and dielectric constant which will be
        assigned to newly added media (for example, when you change from
        perfect ground or free space to real ground). You may want to
        assign the values of your local ground to this selection.
        Representative values for common ground types are given under
        "The Media Menu", below.

        TU -- TABLE UNITS

        You can choose to have tabular far-field pattern data (Main Menu
        selection 'TA') presented in terms of dBi (or dBref), V/m at 1
        mile (1 kW ref), or V/m at 1 km (1 kW ref). When either of the
        latter two is chosen, the antenna is assumed to have an input
        power of 1 kW for determining table V/m values, regardless of the
        'PO' setting.

        GL -- GUIDELINE CK

        If desired, you can disable the automatic guideline check. If you
        do, you can still run it with the Main Menu 'GC' command. It's
        recommended that the automatic guideline check be left enabled.

        GF -- GND FILE TOL

        This sets the tolerance used to determine if a ground data file
        is close enough to re-use. When Real, High Accuracy ground is
        chosen, EZNEC checks to see if a ground data file already exists
        having values which are close enough to those needed. "Close
        enough" is determined by looking at the ground complex
        permittivity and matching it with that of the files which have
        been saved. If the two match within the tolerance, the file data
        are used instead of re-calculating them. The default tolerance of
        7% generally won't significantly reduce accuracy by re-using


                                       84




        existing files if analyzing horizontal antennas. However, if
        analyzing wires very close to the ground or in situations where
        small changes must be discerned, the tolerance should be reduced,
        possibly to 0.1% or less. You may want to loosen the tolerance if
        you do particularly wide frequency sweeps, to avoid excessive re-
        calculation of ground files.

        PO -- POWER

        This sets the power used as a reference when reporting voltages,
        currents, power, power losses, and near field strength. If you
        enter zero for this selection, the source voltages and currents
        you specify are absolute. If you enter any other power, the
        voltages and currents maintain the same ratios, but are scaled so
        that the total power applied to the antenna equals the power you
        specified. This allows you to directly read the source and load
        voltages, currents, powers, losses, and near field strengths
        which would occur with the specified total power applied to the
        antenna.

        SC -- STEPPED DIA CORR

        Two choices are available, "On" and "Off". In the "On" position,
        stepped diameter correction is enabled and will be used any time
        wires meet the criteria. If set to "Off" it is disabled. It is
        recommended that it be left in the "On" position. See p. 51 for
        more information about Stepped Diameter Correction.

                                  The Wires Menu

        The Wires Menu is entered by making selection 'WI' in the Main
        Menu. At the upper portion of the display is a summary of the
        wires: connections, end coordinates, diameter, and number of
        segments. Wire end coordinates are defined as x, y, z coordinates
        relative to the origin (see the description and diagrams on p.
        71, 72). The "Conn." column shows connections to other wires; if
        a wire end is connected to more than one other wire, only one
        connection will show in this column. Since defining the wires
        usually is the most time-consuming part of describing the
        antenna, EZNEC includes several shortcuts to make the task faster
        and easier. Remember that you don't have to use the shortcuts --
        they're there only for your convenience if and when you want to
        use them. The apparent complexity of this menu is mostly due to
        the number of shortcuts EZNEC provides. More information on wires
        can be found on p. 47, CONSIDERATIONS FOR MODELING WIRES and p.
        45, MODELING THE ANTENNA STRUCTURE.






                                       85




            Entering or changing wire coordinates

        Note that all wires are straight, extending from one set of end
        coordinates to the other. If two wires have the same end
        coordinates they're considered to be connected. (They are also
        considered connected if their end coordinates are within about
        1/1000 segment length.) If a ground is specified and a wire end
        has a z coordinate of zero (actually, within about 1/1000 segment
        length of zero), the end is considered to be connected to ground.
        The NEC-2 calculating engine used by EZNEC will also connect
        wires at segment junctions when the segment junctions coincide.
        However, taking advantage of this is strongly discouraged. First,
        EZNEC won't show you that they're connected. Second, the
        connection will be broken if you change the length or number of
        segments of either wire, leaving the wires crossing at a non-
        segment junction. Wires which cross or coincide can result in
        major inaccuracies or a calculating engine crash, so this
        situation should be avoided. Connect wires only at their ends.
        EZNEC does not permit wires to extend below ground, so if a
        ground is specified and the z coordinate of any wire is more
        negative than -1/1000 segment length, an error message will
        result. Wires with both coordinates within 1/1000 segment length
        of ground, or within a wire radius of ground, will be considered
        to be lying on the ground and will cause an error message.

        To enter or change wire coordinates, simply type the wire number.
        (<Enter> is required following the number if there are more than
        nine wires.) This will highlight end 1 of the selected wire. To
        move to end 2, press the right arrow key. Wire coordinates can be
        entered in two different ways. Either may be used as desired:

            1. Conventional. Just enter the x, y, and z coordinates when
            prompted, separating them with commas. If you need to change
            only one or two coordinates, it's not necessary to reenter
            all three. Simply leave unchanged coordinates blank. For
            example, to change coordinates 3.75,4.95,.713 to
            3.85,4.95,.713 you only need to type '3.85,,'. This shortcut
            also works in the Group Edit mode, so you can change only one
            or two coordinates of a group of wires if desired.

            2. As connections to other wires. To connect a wire end to
            another wire end, type 'W#E#' for "Wire number End number".
            For example, to connect an end to wire 3, end 1, type 'W3E1'
            at the prompt for coordinates. The correct coordinates will
            be entered and the connection shown in the "Conn." column.
            Note that if there are several connections to the same end,
            the connection shown in the "Conn." column may not be the one
            just entered.




                                       86




        Once entered, the end coordinates can be modified in several
        ways. When using the Length and Rotate features it's helpful to
        keep in mind the following rule used by EZNEC: Only the
        coordinates of the selected end will be changed; the other end
        won't change. Important: Because of the finite length of numbers
        used by the computer, changes are seldom exact. An operation
        isn't necessarily exactly reversible, and errors will accumulate
        with repeated changes. Don't depend on complementary operations
        (such as rotating equal amounts in opposite directions) to
        restore your model to exactly the original configuration,
        particularly when repeated changes are made.

            1. Changing the length. Once wire coordinates are entered,
            the length can be changed as follows: Select the end to be
            changed, then type 'L###' where "###" is the new wire length.
            The coordinates of the selected end will change to make the
            wire the new length, in the same direction as before. To
            illustrate its use, consider an inverted vee antenna guyed to
            the corners of a lot from a single tower. First create a long
            inverted vee extending from the tower to the lot corners by
            entering the coordinates of the tower top and lot corners for
            the wire ends. Then change the lengths of the wires to their
            real values. This eliminates the trigonometric exercise of
            figuring out what the actual antenna end coordinates are.
            Alternatively, a change in length, rather than a new length,
            can be specified by entering 'L+###' or 'L-###'. For example,
            'L-3.4' would shorten the wire by 3.4 units. This is a
            powerful feature for studying things like the effect of
            changing the length of drooping radials. Again, the feature
            can be used in the Group Edit mode, for example to change the
            lengths of all the radial wires in a top hat. You can't
            change the length of a zero-length wire, since EZNEC doesn't
            know in what direction to lengthen it.

            2. Rotating the wire. The wire can be rotated by entering
            'RA###' (Rotate Azimuth) or 'RE###' (Rotate Elevation) where
            "###" is the desired amount of rotation in degrees. The
            rotation amount can be positive or negative, with positive
            meaning counterclockwise azimuth rotation or upward elevation
            rotation. (Note: Positive rotation remains CCW even if
            azimuth angles are shown as compass bearings. The prompts at
            the bottom of the screen will remind you.) The highlighted
            wire end will move. The other end will be the center of
            rotation and will stay put. When performing elevation
            rotation you won't be permitted to rotate a wire closer than
            about 1 degree to vertical, and you won't be able to rotate a
            vertical wire in elevation. This is because EZNEC keeps the
            same azimuth direction for an elevation-rotated wire, and it
            can't tell which direction to move a vertical wire. There's
            no similar restriction on azimuth-rotated wires. The rotation


                                       87




            ability is a powerful feature for defining vee-type antennas
            and delta loops. You can begin by defining a straight antenna
            then rotating the wires to the desired angle. An inverted vee
            example appears in TEST DRIVE in the RUNNING EZNEC chapter. A
            process similar to the TEST DRIVE example can be used to make
            a delta loop: Make a dipole with two wires, each 1/3
            wavelength long (use wavelengths for units if desired).
            Rotate the wire ends down 60 degrees, making an inverted vee
            as in the example. Then add a third wire, specifying end
            connections to connect to the ends of the "inverted vee". If
            you want to adjust the height in feet, just change the units
            to feet, then adjust the height.

            Entering or changing wire diameter

        Note that the wire diameter might be in different units than the
        wire end coordinates. Watch the heading of the "Dia" column and
        the prompt. The diameter can be entered directly or as a wire
        gauge (AWG). To enter it as a wire gauge, type '#--' where "--"
        is the gauge, at the prompt. Wire gauges larger than #0 (e.g.,
        #00) aren't permitted.

            Entering or changing the number of segments

        Entering the number of segments is simple; deciding how many to
        enter can be more difficult. See p. 46 in the MODELING WITH EZNEC
        chapter for more information. If you wish, you can have EZNEC
        automatically adjust the number of segments; see "auto Seg"
        below. The total number of segments is shown at the bottom of the
        Segs column.

            Connecting wires to each other

        Wires can be connected only at their ends. (Technically, they can
        also be connected at a coincident segment junction, but this is
        strongly not recommended.) Two ends are considered to be
        connected whenever their coordinates are the same. See "Entering
        or changing wire coordinates", p. 86, for more information.
        Please note that the Wires Menu shows coordinates only to three
        decimal points, so it may appear that wires have identical
        coordinates when they actually don't. You can verify wire
        connections by looking at the "Conn" column of the Wires menu or
        by observing the wire connection markers in the View Antenna
        display. 

            Connecting a wire to ground

        If the ground type is Real or Perfect, a wire end is connected to
        ground by specifying a z-coordinate of zero.



                                       88




            Wire Coordinate Errors

        Wires must have a non-zero length. Also, if a ground plane
        (either real or perfect) is specified, the wires can't lie on the
        ground plane (within 1/1000 segment length of zero z coordinates
        for both wire ends), or below ground (more negative z coordinate
        than -1/1000 segment length). (Negative z coordinates are always
        permitted with Free Space ground type.) If a coordinate error
        occurs, the affected wires are shown as bright text and a
        description of the error appears in the "Conn" column. Newly
        added wires are given end coordinates of 0,0,0 so they fall into
        this category. If you attempt to leave the Wires Menu while zero-
        length wires are present, you'll get an error message and be
        returned to the Wires Menu until the problem is corrected. The
        error message includes a prompt which permits you to delete all
        zero-length wires. You can choose to do this or return to the
        Wires Menu and fix or delete the defective wires. If wires are in
        or on the ground plane when not permitted, an error message will
        appear. You'll be sent to the Main Menu where you can correct the
        problem by specifying Free Space as the ground type or by
        returning to the Wires Menu to raise the wires. You won't be
        permitted to run or normally exit EZNEC with a wire coordinate
        error present.

            Add wires

        To add wires, choose 'A'. At the prompt, enter the number of
        wires you want to add and they will be added at the end of the
        list. If you want to add wires anywhere else, enter two numbers
        separated by a comma. The first number is the number of wires to
        add; the second is the wire number to place them after. To place
        new wires at the very front of the list, enter '0' for the second
        number. Sources, loads, and transmission lines will stay on the
        same wires they were on before, even if the wire numbers change.
        Wires can also be added in the Group Edit mode (see below).

            Delete wires

        Enter 'D' to delete wires. If you enter a single number at the
        prompt, the wire with that number will be deleted. If you enter
        two numbers separated by a comma or hyphen, the two wires and all
        between will be deleted. If the second number is greater than the
        number of wires, wires from the first number to the last wire
        will be deleted. If there are any sources, loads, or transmission
        lines on wires to be deleted, EZNEC will notify you and ask for
        confirmation before making the deletion. Sources and loads on
        other wires will stay on the same wires they were on before, even
        if the wire numbers change. Wires can also be deleted in the
        Group Edit mode (next section). The Delete option won't appear if
        there is only one wire.


                                       89




            Import wires

        This choice allows importing wire descriptions from an ASCII
        file. The imported wires can be added to the existing description
        or can replace the wires in the existing description. This is not
        intended as a general substitute for EZNEC's normal entry system,
        but a way to enter wire coordinates generated by an external
        program into EZNEC. This feature shouldn't be confused with
        EZNEC's ability to merge standard EZNEC description files. For
        information on how to merge description files, see p. 123. The
        default directory for import wire files is the current (EZNEC
        program) directory.

            show step dia Corr

        This selection is active even if Stepped Diameter Correction has
        been disabled. (See p. 51 for more information about Stepped
        Diameter Correction.) By typing 'C', you can see which wires
        would be affected by the stepped diameter correction and the
        values EZNEC would use for calculation. Each potentially
        corrected group of wires will be highlighted. You will see that
        the length of the group is changed slightly, and the diameter of
        all the wires in the group will be the same. The new values are
        those of the equivalent constant-diameter wire EZNEC has
        calculated. All groups fitting the criteria for correction will
        be shown. The coordinates of wires which aren't corrected are
        replaced by a brief message telling one of the criteria for
        correction which the group is lacking. (A "group" is a series of
        wires connected to each other.) If you have connecting wires with
        different diameters which aren't shown as being corrected, make
        sure they're not in a part of the antenna in which small
        calculation errors will have an important effect on the results.

            Group Edit

        This powerful set of features allows adding, deleting, copying or
        moving groups of wires, or entering a single value for the
        coordinates, diameter, length, or number of segments of a group
        of wires. Since this feature is common to several menus, it's
        explained following the sections on menus. See GROUP EDIT, p.
        120.

            chg Ht

        You can change the height of the entire antenna by pressing 'H'.
        The height of a group of wires can be changed by using the Group
        Edit mode (see above).





                                       90




            create Radials

        This easy-to-use feature is used to create a radial structure
        centered at any point. After typing 'R', you will be asked for
        prototype wire number(s). If you enter a single number, that wire
        will become the prototype. A group of wires can be used as the
        prototype by entering the numbers of the first and last wires in
        the group, separated by a comma or hyphen. If a group is
        specified, the wires must be connected in sequence, and end 2 to
        end 1. End 1 of the prototype wire, or of the first wire in the
        prototype group, becomes the center of the radial structure.
        After entering the prototype specification, a prompt appears
        asking for the number of radials. Specify the total number of
        wires or wire groups you wish to result from the process. The
        specification will be rejected if the prototype wires lie in a
        vertical line.

            auto Seg

        Pressing 'S' will adjust the number of segments of all wires to
        the smallest number meeting modeling guidelines. You can choose
        between conservative and minimum recommended guidelines. NOTE
        that this doesn't guarantee proper segmentation for all
        situations. Many antennas require more segments (sometimes, many
        more) than even the Conservative automatic segmentation provides.
        You should always try changing the number of segments to see if
        the results change substantially. See MODELING THE ANTENNA
        STRUCTURE, p. 45 and CONSIDERATIONS FOR MODELING WIRES, p. 47 for
        more information about segmentation. Do not rely too heavily on
        automatic segmentation!

            Taper seg

        There are times when it's advantageous to make some segments very
        short. When results are very sensitive to source, load, or
        transmission line location, accuracy can be improved by putting
        the source, load, or transmission line on a very short segment.
        When several wires intersect at an acute angle, accuracy might be
        improved by using short segments near the junction. However,
        simply increasing the number of segments to satisfy the length
        requirement of the critical segments may lead to undesirably slow
        program execution. An alternative is to break the joining wires
        into several one-segment wires of  different lengths, short near
        the junction and increasing as distance from the junction
        increases, to achieve high accuracy with a moderate total number
        of segments. (See "Segment Length Tapering for Multiple Wires
        Joining at an Acute Angle", p. 67.) EZNEC provides an automated
        method of doing this segment length tapering. It's intended as an
        advanced feature for use in special cases only after you're
        completely familiar with EZNEC. Note that the segment length


                                       91




        tapering process permanently changes the antenna description so
        it's recommended that you save the description before you start.
        (EZNEC will ask you if you want to do this before you begin.)
        When several wires are to be tapered, you also may want to save
        intermediate descriptions in case you make a mistake.

        After typing 'T' and responding to the question about saving the
        description, you're asked which wire to taper and at which end(s)
        to put the short segments. Respond with the wire number and the
        end(s) requiring short segment length. If both ends must have
        short segments, enter 'B' (both) for the end number. EZNEC will
        then ask you for the minimum and maximum permissible segment
        lengths. You can use the default values of 1/400 and 1/25
        wavelength by pressing <Enter>, or specify different values.
        (Guidelines will be exceeded if these limits are made much more
        extreme.) EZNEC will make the shortest segment equal to the
        minimum you specify and will not exceed the maximum with any
        segment. The lengths are in current units, or in wavelengths if
        you follow the number with 'w'. For example, '.002w,.02w' will
        taper lengths from .002 wavelength to .02 wavelength. Don't
        forget to add the "w" if you intend to specify in wavelengths.
        The program then will respond with the number of wires and
        segments it will use to replace the wire. If this is ok, press
        'y' or <Enter> and the wire will be replaced; if not, press 'n'
        and you'll be able to specify new minimum and maximum segment
        lengths. Doubling the minimum length will reduce the number of
        wires and segments by one per tapered end. The result of choosing
        a different maximum will depend on several factors and may
        substantially change the resulting number of segments.

        The new wires will replace the old one. After you have tapered
        the first wire, notice that some wires appear in color. These are
        the new wires. If you want to taper the next original wire,
        select 'T' again, and give the number of the first non-brightened
        wire (which is the next original wire), followed by the end(s) to
        have the short segment when tapered. If there are more total
        wires than the screen can display at once, this wire will be the
        bottom one on the screen. Continue the process until you have
        tapered all the wires you wish to. The brightening/coloring of
        tapered wires will persist until the antenna description is saved
        and recalled or until EZNEC is exited and restarted. (Modifying
        the wires to cause an error such as extension below a ground
        plane will also return the color to normal after the error is
        corrected.)

        Sources, loads, and transmission lines which are at the end of a
        wire, or at the center of a wire which is being segment length
        tapered at both ends, will automatically be moved to the correct
        locations on the new wires. Those at other locations may not end
        up where desired. It's a good idea to always check the placement


                                       92




        of all sources, loads, and transmission lines after doing a
        segment length taper.

            chg Units

        Choice 'U' performs the same function as 'UN' in the Main Menu -
        it permits changing the units of measure. This is particularly
        useful for switching between wavelengths and other units, or for
        converting a design between metric and English units.

        A second use of this selection is to permit changing units
        without changing numbers. This is done by preceding the units
        choice with '!'. That is, a coordinate of 3.14 meters will become
        3.14 feet when changing units from meters to feet. This feature
        is included because of a potential trap. You carefully enter all
        your antenna wire end coordinates, then discover the units are
        meters, not feet as you intended. If you change the units, the
        units change but the wires stay the same (incorrect) length as
        before. If you fall into this trap, choose 'U' and select the new
        units, preceding the choice with '!' (for example, '!f' for
        feet). The units will change but the numbers you've entered for
        end coordinates and wire diameter will remain the same.

            Pres Conn

        When Preserve Connections is on, moving a wire end will also move
        the coordinates of all connected wire ends, so they stay
        connected to the modified wire. It's a very useful feature in
        doing certain kinds of antenna modifications, but results can be
        surprising and confusing if Preserve Connections is on when
        thought to be off. Because of this, the ON indicator blinks when
        the feature is on. When using Preserve Connections, frequently
        use View Antenna to make sure your changes are having the desired
        result, and save your description before making changes. A
        typical use would be changing the diameter of a top hat which has
        a perimeter wire. You can quickly and easily do this by turning
        Preserve Connections on, and using Group Edit to change the
        lengths of the radial wires. The perimeter wires will be
        automatically modified to be at the new perimeter.

            View antenna

        Type 'V' to see what the antenna looks like. This operates
        identically to the 'VA' selection in the Main Menu except that
        you'll be required to delete or modify any zero-length wires
        before viewing the antenna. See The View Antenna Display and
        Menu, p. 106, for more information.





                                       93




                                 The Sources Menu

        To add or delete sources type 'A' or 'D'. To modify a source,
        type the number of the source. Group editing functions also are
        available - see GROUP EDIT, p. 120. Sources are inserted in the
        specified wire. They can be envisioned as being in the center of
        the segment, but actually are distributed along the whole
        segment. No more than one source may be placed at a given segment
        on a wire. At least one non-zero source always must be specified.
        Note: Sources appear in series with loads and in parallel with
        transmission lines which are on the same segment. See USING
        SOURCES, p. 57, for additional information about sources.

            Specifying the source position

        Source position specification with EZNEC is a bit different than
        for NEC. In EZNEC, you specify the wire number and percentage of
        the distance from end 1 of the wire. For example, to put a source
        at the middle of wire # 1, you enter '1,50' at the prompt (for
        "Wire 1, 50% of the way from end 1"). The source will be put on
        the segment closest to the center of the wire, and stay at the
        same position (as closely as possible) on the same wire, even if
        you add or delete wires, or change lengths or numbers of
        segments. Voltage and current sources are placed on segments;
        split voltage and current sources simulate a source placed at a
        segment junction by creating two sources placed on the adjacent
        segments. Split sources cannot be placed at open wire ends. A
        conventional source placed on the segment nearest an open end
        will give unpredictable results.

        When you specify a position, EZNEC will place it at the nearest
        segment (or, for split sources, segment junction) and tell you
        where its actual position is. The specified position is saved,
        and each time a change is made to the wires the source is moved
        as close as possible to that position. The source will stay on
        the same physical wire even if the wire number is changed due to
        adding, deleting, or moving wires. Both the actual and specified
        positions are shown in the menu for easy reference.

        The position of a source at a wire end or center may be entered
        as 'w#e!' where # and ! are the wire and end number,
        respectively, or 'w#c' to place at the center of wire number #.
        For example, 'w5e2' will put the source at end 2 of wire 5, 'w1c'
        at the center of wire 1.

        Avoid placing transmission lines or unequal loads on the segments
        which contain split sources. This will lead to unexpected
        results. (You can see where the halves of the split sources are
        in the View Antenna display.) See USING SOURCES, p. 57.



                                       94




            Source amplitude and phase

        There are no restrictions on amplitude or phase except that if a
        single source is specified, it must have non-zero amplitude. If
        only one source is specified, the amplitude and phase will have
        no effect on the pattern or gain (as long as the amplitude isn't
        zero). If you enter a power level from the Options Menu, the
        amplitudes and phases are considered to be relative. Reported
        source and load voltages, currents, powers, and losses, and
        segment currents, are adjusted for the specified power level.
        There is no provision to specify separate power levels for each
        source. Note: Source amplitudes are in RMS, not peak as in NEC.

            Source type

        EZNEC features both voltage and current sources. If only one
        source is used the choice won't make any difference in the
        impedance, gain, or pattern. For arrays driven with multiple
        sources, the choice can make a major difference in array
        performance, and the choice should reflect the desired driving
        conditions. If you need to put a source at a wire junction (such
        as on an inverted-vee antenna), choose a split voltage ('SV') or
        split current ('SI') source. See USING SOURCES, p. 57, for more
        information about split sources.

            Adding and deleting sources

        Addition and deletion are done the same as with wires. Refer to
        "The Wires Menu", p. 85, for information. The Delete option won't
        appear if only one source is defined.

            Connecting a source to ground

        Sources appear in series with the wire, so a grounded source is
        specified by inserting the source at a grounded wire end. (This
        places the source on the segment which is grounded.) To place a
        source between ground and a wire end which isn't at zero height,
        you'll first need to add a wire connecting the end to ground,
        just like you would have to do with a real source or feedline and
        antenna.

            Group Edit

        See GROUP EDIT, p. 120.








                                       95




                                  The Loads Menu

        Load placement, connection, addition, and deletion operate like
        corresponding source operations, with one difference. If no loads
        are specified, a single load can be simultaneously added and
        selected by typing '1' from the Loads Menu. This choice appears
        at the bottom of the screen when no loads are specified. Refer to
        "The Sources Menu", above, for general information. Loads are
        inserted in the wire, in series with transmission lines and all
        types of sources which are on the same segment. Like sources, a
        load is distributed along the segment it's placed on.

            Specifying or changing impedance

        Impedances may be entered either as resistance and reactance (R +
        jX) or as a quotient of Laplace transform polynomials of up to
        fifth order. All loads must be entered as the same type; if the
        type is changed, all existing loads will be deleted (after
        notifying you and receiving confirmation). The type which is in
        effect is indicated by the heading of the right-hand column or
        columns. The type is changed by typing 'T' at the Loads Menu
        prompt. Series or parallel RLC circuits may be specified as R, L,
        and C values as explained below.

            Using Laplace transforms

        The advantage of using Laplace-transformed load impedances is
        that the impedances will be automatically adjusted as the
        frequency is changed. A detailed discussion of the direct use of
        Laplace transforms is beyond the scope of this document. However,
        you can still take advantage of their frequency-scaling
        characteristics for certain kinds of circuits without knowing how
        they operate, as explained below.

        To change the load type from R/X to Laplace, press 'T' from the
        Loads Menu. The heading will change to indicate Laplace type
        loads and "Select to show values" will appear in place of the
        load impedances. After selecting a load, moving the entry cursor
        to "Select to show values" will bring up two rows of numbers near
        the bottom of the screen, and the prompt "Coefficient, 'S', or
        'P'". If you are familiar with the use of Laplace transforms, you
        can directly enter the coefficients for numerator and denominator
        polynomials up to fifth order. At least one denominator
        coefficient must be non-zero. 

        Alternatively, you can have EZNEC automatically calculate the
        coefficients for you if the load can be represented as a series
        or parallel RLC circuit. (All three components don't have to be
        present.) This is done by pressing 'S' (for series RLC circuit),
        or 'P' (for parallel RLC). Another prompt will then appear, for


                                       96




        the values of R in ohms, L in henrys, and C in farads. Three
        values must be entered in the order R,L,C, separated by commas.
        Enter 0 to indicate a missing component. For example, a series or
        parallel combination of 200 pF and 3 uH would be entered as
        '0,3E-6,200E-12'. (Note the entry order: R first, then L, then C.
        In this example, R is missing so is entered as 0, even though a
        missing R actually has an infinite value in the parallel case.)
        The corresponding Laplace coefficients will be entered for you. A
        common error is to forget to enter the 'S' or 'P' before entering
        R, L, and C. If you do this, EZNEC will beep and refuse the
        entry.

        When finished entering the coefficients for the selected load,
        press <PgUp> or <PgDn> to enter values for another load or <ESC>
        to return to the Loads Menu.

            Group Edit

        See GROUP EDIT, p. 120.

                           The Transmission Lines Menu

        EZNEC uses NEC transmission line models. There are several very
        important differences between these and real-life transmission
        lines, which are discussed in USING TRANSMISSION LINES beginning
        on p. 59. Please acquaint yourself with these differences before
        using them.

        A transmission line is connected to a segment as though the
        segment were broken and the transmission line terminals were
        connected across the gap; that is, it's placed in series with the
        segment. A transmission line is connected in series with loads,
        and in parallel with sources and other transmission lines, which
        are connected to the same wire segment.

            Adding and deleting transmission lines

        Addition and deletion are done the same as with wires. Refer to
        "The Wires Menu", p. 85, for information.

            Group Edit

        See GROUP EDIT, p. 120.









                                       97




            Specifying transmission line end positions

        Transmission line end positions are specified in the same way as
        source positions. See "The Sources Menu", p. 94, for information.
        One end can be specified as being either short or open. If both
        ends are short, open, or a combination of the two, an error will
        result. Each end which isn't open or shorted must be connected to
        a wire. See USING TRANSMISSION LINES beginning on p. 59 for more
        information.

            Specifying transmission line length

        The length can be specified in three ways: as the actual physical
        distance between ends, as an electrical length in degrees, or as
        a physical length in the current units. Note: If you want
        realistic results from a frequency sweep, don't specify lengths
        in electrical degrees, since the equivalent physical length will
        be adjusted at each frequency to maintain the specified
        electrical length. That is, you'll have a magical transmission
        line which has the same electrical length at all frequencies.
        "Actual length" is not allowed if one end is open or shorted. If
        "actual length" is specified, then an end is declared open or
        shorted, the length will be changed to zero and an error will
        occur.

        Because the transmission line models are mathematical and not
        physical, EZNEC won't be the least upset if you specify a length
        of 1 meter and connect the ends to two segments which are 10
        meters apart. The antenna will be difficult to construct,
        however!

            Specifying characteristic impedance (Z0)

        Characteristic impedance can be entered in several ways: as a
        number (in ohms), as a common cable type, or as the diameter and
        spacing of a two-conductor air-dielectric line. When the cursor
        is in the Z0 column, a prompt appears at the bottom of the screen
        showing the options, including several cable types which can be
        directly entered. For example, enter "R62" or "RG62" to set the
        Z0 equal to that of RG-62/U. (This will also enter the correct
        velocity factor.) If you type 'A' (for air line), you'll get
        additional prompts for wire diameter and spacing. Note: The loss
        characteristics of cables are NOT modeled. EZNEC transmission
        line models are lossless.








                                       98




            Specifying velocity factor

        The velocity factor is entered the same way as Z0, described
        above. If entered as a number, it has to be greater than zero and
        less than or equal to 1. This choice isn't available if you've
        specified the cable length in electrical degrees.

            Specifying reverse/normal connection

        This selection allows you to reverse the transmission line
        terminals. You may want to do this to achieve a frequency-
        insensitive 180 degree phase shift, or to compensate for
        oppositely-oriented wires. Consider a twinlead transmission line
        connected between wires 1 and 2. Call  one conductor "a" and the
        other "b". If the transmission line is connected in the "Normal"
        sense and conductor "a" is closer to end 1 of wire 1, it will
        also be the closer of the two conductors to end 1 of wire 2,
        regardless of how the wires are oriented. Conductor "b" will be
        closer to end 2 on both wires. If the connection is reversed, "a"
        will be closer to end 2, and "b" to end 1, on the second wire.

                                  The Media Menu

        This menu is available when "real" ground is selected. The ground
        constants entered in this menu are used somewhat differently for
        two purposes. When Real/Fast Analysis or Real/High-Accuracy
        ground is chosen, the constants of the first medium are used
        during determination of antenna impedance and currents. The
        constants of both media are used during pattern calculation, by
        modifying the strength and phase of the field reflected from the
        ground. Ground constants are not used if Free Space or Perfect
        ground is specified, and are used only for pattern calculation if
        Real/MININEC-type ground is being used. Real/MININEC-type
        analysis assumes a perfect ground during impedance and current
        calculations.

        The ground model consists of one or two "media". If "R"-type
        (radial) boundary is chosen, the first medium is a disk, with the
        second medium occupying the remainder of the (infinite) ground
        plane. If the boundary is "X"-type (linear), the first medium
        occupies the ground to the -x side of a line parallel with the y
        axis, the remainder of the ground being the second medium. The
        "boundary" is the radius of the disk ("R"-type) or the x value of
        the dividing line ("X"-type).

        NOTE: Regardless of the position of the antenna, the ground under
        the antenna is assumed to have the characteristics of the first
        ground medium (including a height of zero), during impedance and
        current calculations with Real/Fast Analysis and Real/High-
        Accuracy grounds.


                                       99




            Entering the conductivity and dielectric constant

        The conductivity and dielectric constant (relative permittivity)
        of the ground vary with the type and dampness of the soil.
        Typical values for several types of soil, as well as a map of
        typical average soil conductivities for the U.S., are given on
        page 3-3 of The ARRL Antenna Book, 15th or 16th Ed. (ARRL) and in
        other handbooks. Values from The ARRL Antenna Book for some
        common ground types are:

        Ground Type                Quality           Cond.   Diel.Const.
                                                     (S/m)

        Fresh water                                  .001      80
        Salt water                                   5         81
        Pastoral, rich soil        very good         .0303     20
        Pastoral, heavy clay soil  average           .005      13
        Rocky, typ. mountainous    poor              .002      13
        Cities, industrial areas   very poor         .001       5
        Cities, hvy industrial     extremely poor    .001       3

        As a shortcut, values for very good, average (good), poor, or
        very poor soil can be entered by typing 'VG', 'A' or 'G', 'P', or
        'VP' when either the conductivity or dielectric constant is
        highlighted. When a ground is first specified or when a new
        medium is added, values of conductivity and dielectric constant
        are assigned according to the DEFAULT GND CONSTANTS choice in the
        Options Menu. These values can be changed at any time by entering
        the new value while the value to be changed is highlighted. See
        p. 55 for more information about the limitations of the ground
        model.

          Entering the R or X boundary coordinate

        The heading of the right-hand column shows the boundary type: "R"
        for radial boundary and "X", linear. This can be changed by
        selecting 'B' from the Media Menu when no media are highlighted.
        The boundary coordinate is the x coordinate (linear boundary) or
        distance from the origin (radial boundary) where the boundary
        begins; the second medium extends to infinity. The boundary of
        the first medium is fixed at zero. The value of the second
        boundary must be positive or zero. If the boundary of the second
        medium is zero, the impedances and currents will be calculated
        using the constants of the first medium, while the far field will
        be calculated using the constants of the second. Using an extreme
        conductivity for the first medium to simulate a low-resistance
        ground connection isn't advised; use the MININEC-type ground for
        this purpose. See MODELING GROUND, p. 54, for more information.




                                       100




          Entering the medium height

        The height of the first medium is fixed at zero. The height of
        the second must be zero or less than zero. (The height is the z-
        coordinate of the medium.)

        Regardless of the position of the antenna, the height of the
        ground under the antenna is always assumed by the program to be
        zero for calculation of impedances and currents.

          Adding and deleting media

        A second medium is added and selected by entering '2'. To delete
        the second medium, type 'D', then any number 2 or greater.
        Entering '1' as the medium to delete will cause medium 2 to
        replace medium 1, and medium 1 to be deleted.

          Changing the boundary type

        Typing 'B' from the Media Menu toggles the boundary type between
        radial and linear. The right-hand column heading shows the type
        ("R Coord" for radial, "X Coord" for linear).

                       The 2D Pattern Plot Display and Menu

        The 2D Pattern Plot Display shows a two-dimensional (2D) "slice"
        of the three-dimensional (3D) antenna pattern. Elevation "slices"
        are exactly that -- flat slices as though cut with a knife.
        Azimuth "slices", however, aren't flat portions of the 3D
        pattern, but are somewhat conically shaped. The best way to
        visualize the actual shapes of the "slices" is by using the
        Highlight Slice feature of the 3D Pattern Plot display, described
        beginning on p. 104.

        When an Azimuth or Elevation type was chosen with Main Menu
        selection 'PT' (Pattern Type), operation of the 2D Pattern Plot
        Display is straightforward. It displays the single pattern
        "slice" as specified in the Main Menu. The few available
        functions are described below.

        When 3D is chosen as the Plot Type from the Main Menu (choice
        'PT'), an additional option is available: the displayed "slice"
        can be chosen while viewing the 2D plot. Details are described
        below.

        A small menu appears in the upper right corner of the screen
        while the plot is on the screen. Following are the selections and
        their effects.




                                       101




          Analyze and annotate plot

        This runs ANALYZE, and the results (gain, beamwidth, front/back
        or front/side ratio, etc.) are shown on the plot along with lines
        indicating the directions of maximum gain, 3-dB points, and
        sidelobe. The green line shows the direction of maximum field
        strength. Magenta (red-violet) lines indicate the -3dB points,
        and the cyan (blue-green) line shows the direction of the
        sidelobe. See Main Menu ANalyze, p. 78, for more information. If
        multiple traces are on the screen, only the "primary" trace is
        analyzed. In normal operation, this is the one which was
        calculated. In TraceView mode, it's the one selected from the
        Main Menu or at the start of the program. If ANALYZE is selected
        following a frequency sweep, the last pattern calculated (the
        highest frequency if stepped, or the last read from the list) is
        analyzed. ANALYZE results are linearly interpolated to 0.1 degree
        resolution between calculated points.

          Print screen

        Prints the plot on the printer. If you've chosen to print an
        abbreviated description under the plot (see "The Options Menu",
        p. 82) and ANALYZE hasn't been run you'll get an additional
        prompt: "(A)nalyze & incl on print". Typing 'A' at this prompt
        will cause ANALYZE to run. The results will be included in the
        abbreviated description below the plot but not on the plot.
        Normal printing is disabled and this selection doesn't appear
        when colors are reversed (see "Rev Colors: X,Y", below).

          Trace: C,D,S,R

        Typing 'C' (Clear trace) will have an effect only if more than
        one trace is on the screen. A list of recalled traces will appear
        and you can choose to clear (remove) one or all of them.

        'D' (Delete), 'S' (Save), and 'R' (Recall) operate on traces just
        like the equivalent Main Menu selections do on antenna
        descriptions. If viewing a "slice" of a 3D plot, they operate
        only on the 2D "slice" which is displayed. If a 3D plot (file
        extension .PF3) is specified as a trace to recall, only one
        "slice" is recalled at a time -- you will be asked to specify
        which one. Trace files are saved in the same subdirectory as the
        antenna description (.EZ) files but are given the extension
        ".PF". Files in earlier EZNEC/ELNEC format (.ENT extension) can
        be read, but EZNEC cannot write files in that format. If no
        extension is specified when saving or recalling a plot, ".PF"
        will be added. See SAVING, RECALLING, AND DELETING FILES, p. 123,
        for the use of "wild cards" to list selected files. When traces
        are recalled, they are automatically scaled to the current grid
        so that field strength values read from the graph are accurate.


                                       102




        If the outer ring value is set to Automatic (Main Menu selection
        'OR'), the outer ring value will change as necessary to scale to
        the trace with the largest maximum value.

        The file names of recalled traces are shown at the left of the
        display. An extension of ".PF" is not shown. If a 3D plot "slice"
        has been recalled, the file name is followed by an abbreviated
        slice description. For example, "A80" means an azimuth "slice" at
        an elevation angle of 80 degrees.

          Rev colors: X,Y

        EZNEC has the ability to reverse the plot colors to allow
        inserting the plot into a Windows document. (See RUNNING EZNEC
        UNDER WINDOWS, p. 26.) Two options are available. "X" makes black
        white and all other colors black. "Y" makes black white and
        leaves all other colors unchanged. To restore colors to normal,
        press "X" or "Y" again, or the <ESC> key. Normal printing with
        the 'P' key is disabled while the colors are reversed.

          Cursor: (arrow keys)

        This selection doesn't appear if "Plain/no cursor" Plot Style was
        chosen in the Options Menu (selection 'PS'). If Standard Plot
        Style is in use, a cursor appears on the trace. Pressing the
        arrow keys moves the cursor and the gain value at its location
        appears at the bottom of the display. The cursor color can be
        changed only by running EZSETUP (see p. 20). Pressing the UP
        arrow key will increase the cursor angle or bearing; the RIGHT
        key will move the cursor clockwise.

        The pattern gain at the cursor position is shown at the bottom of
        the screen. When a "slice" of a 3D plot is being shown, "dBmax"
        is dB relative to the maximum gain of the 3D pattern. When a 2D
        plot is being shown (resulting from an azimuth or elevation Plot
        Type selected in the Main Menu), "dBmax" is relative to the
        maximum gain of the 2D pattern.

          Slice: <C>(arrow keys)

        This selection appears only if a 3D calculation was done (by
        specifying 3D Plot Type with Main Menu selection 'PT'). The
        displayed "slice" can be changed by pressing the <Ctrl> key at
        the same time as one of the arrow keys. Both the slice type
        (azimuth or elevation) and angle are changed with these key
        combinations. If an elevation plot is being displayed, the
        <Ctrl>-LEFT and <Ctrl>-RIGHT combinations display elevation
        "slices" with various azimuth angles or bearings. If the <Ctrl>-
        UP or <Ctrl>-DOWN keys are pressed, the display changes to an
        azimuth "slice" and further pressing of these combinations select


                                       103




        the "slice" elevation angle. Pressing <Ctrl>-LEFT or <Ctrl>-RIGHT
        when an azimuth "slice" is being displayed returns the display to
        an elevation "slice". These key combinations function exactly the
        same as for the 3D Pattern Plot Highlight Slice display, and in
        fact the same "slice" and cursor position appear on both the 2D
        and 3D displays. In order to visualize operation, it may be
        helpful to practice with the 3D Pattern Plot Highlight Slice
        display. Description of the 3D Pattern Plot display begins on p.
        104.

        Exit, or Restore Colors: <ESC>

        If colors are reversed, pressing <ESC> will restore them to
        normal. If ANALYZE is on, <ESC> will turn it off (after colors
        are restored). If colors are normal and ANALYZE is off, <ESC>
        will end the 2D display. If you entered the display via the 3D
        Pattern Plot, it will return you there. Otherwise, the program
        will return to the Main Menu.

                       The 3D Pattern Plot Display and Menu

        The 3D Pattern Plot is shown after calculating when the 3D (three
        dimensional) Plot Type has been chosen (Main Menu selection
        'PT'). It is also shown if a 3D plot has been recalled as the
        primary trace when using TraceView. It shows a full 3D far field
        pattern.

        Many features are available with this display. The plot can be
        rotated for better viewing. A selectable azimuth or elevation
        "slice" can be highlighted, and the field strength value read at
        any point with a positionable cursor. You can go directly from
        the 3D display to the 2D display for more detailed analysis of a
        single "slice".

        Some of the menu selections operate differently when the
        Highlight Slice feature is on. These are pointed out where
        applicable.

          (arrow keys): Rotate; Cursor pos [Highlight mode]

        When Highlight Slice is off (normal mode), the arrow keys rotate
        the display. When Highlight Slice is first turned on, the arrow
        keys control the cursor position. Pressing the space bar <SPC>
        when in Highlight mode changes the function of the arrow keys so
        they can be used to rotate the display. Further presses of <SPC>
        toggles the arrow keys between functions. The menu display always
        shows the current function of these keys.





                                       104




          2: 2D display

        Takes you to the 2D Pattern Plot display (p. 101). Press <ESC> in
        the 2D display to return.

          D: Axes on/off

        Turns the axis display on and off.

          H: Highlight slice

        Switches to the Highlight Slice mode. Highlights one of the
        azimuth or elevation "slices" and enables slice selection and the
        cursor. A readout appears on the left showing the gain at the
        cursor. ("dBmax" is gain in dB relative to the 3D pattern
        maximum.) Some keys change function when in the Highlight mode,
        as described elsewhere in this section.

          M or F1: Menu on/off

        Turns the menu on and off. The cursor is disabled when the menu
        is off.

          O: Select colors

        Operates the same as in View Antenna. See p. ? for a description.
        Note that when Highlight Slice is turned on, the plot dims to a
        gray color. This color can't be changed. Several of the colors
        are shared with the View Antenna display, and the cursor color is
        also used by the SWR Graph.

          P: Print

        Operates the same as in View Antenna. See p. 111.

          R, A: Reset (All)

        'R' returns the plot to the original position and the slice
        selection and cursor position to default values. 'A' also turns
        Highlight off and restores colors to last permanent values.

          S: Save 3D trace

        Saves the entire 3D plot in a file with extension .PF3. This file
        can be recalled for viewing when in TraceView mode (p. 126), or a
        2D "slice" can be recalled and viewed in the 2D display. There is
        no provision for recalling a 3D plot into the 3D display except
        as a primary trace in TraceView mode (see TRACEVIEW, p. 126).




                                       105




          V, <C>V: Reverse colors

        These function the same as for the View Antenna display. See p.
        112.

          <A>XYZ: View from axis

        Pressing <ALT> with X, Y, or Z, will align the display so it is
        viewed from the positive direction of the chosen axis.

          F2: NoFlash on/off

        This functions the same as for the View Antenna display. See p.
        113.

          <C>(arrow keys): Select slice

        (Highlight Slice mode only) Pressing <CTRL> at the same time as
        an arrow key selects the highlighted slice. These combinations
        are used to select both the type (azimuth or elevation) and angle
        or bearing of the slice. They function the same as for the 2D
        display; see p. 103 for more information.

          <ESC>

        If Highlight Slice is off, exits the display and returns to the
        Main Menu. If Highlight Slice is on, <ESC> turns it off.

          <SPC>

        (Highlight Slice mode only) Pressing the space bar changes the
        function of the arrow keys between cursor movement and plot
        rotation.

                        The View Antenna Display and Menu

        The View Antenna display is a powerful feature that gives
        important
        information about the antenna. The three-dimensional display of
        the antenna is useful in verifying that you've described the
        antenna as you intended. Following is a brief description of
        other objects which are or can be included on the screen along
        with the antenna display:

          Coordinate system and origin marker

        The display includes lines showing the directions of the x, y,
        and z axes. The lines are solid when the origin (x,y,z = 0,0,0)
        is at their intersection. They are shown dashed when it isn't. A
        distinctive marker shows the position of the origin.


                                       106




          Source and load positions

        Source and load positions are shown.

          Transmission lines

        Transmission lines and open- and short-circuited stubs are shown.

          Currents

        You can determine a great deal about antenna operation by
        observing the currents flowing on the wires. Current magnitude,
        and optionally phase, are shown, with special indicators to aid
        in interpreting phase. See "Currents", in INTERPRETING THE
        RESULTS, p. 65, to learn more about taking full advantage of this
        important display.

          Segment dots

        Dots show wire segment junctions. These are useful in determining
        that segments are of reasonable length and that segment lengths
        on connected wires are similar in length.

          Wire connection dots

        Wire connections are shown with dots of different color and
        slightly larger size than the segment dots. These help show that
        wires are connected as intended.

          Unconnected wire end markers

        When several wires join at a single point, one or more wires
        might not be connected as intended due to errors in entering the
        antenna description. The unconnected wire end markers show these
        by marking all unconnected wire ends.

          Far-field pattern

        If the pattern has been calculated, it can be added to the View
        Antenna display. This helps you see the relationship between the
        pattern and antenna orientation. If desired, the pattern can be
        made into a semi-solid figure for better visualization.










                                       107




          View Antenna operation: general information

        The display can be rotated, positioned, and zoomed for easier
        viewing. Currents can be independently zoomed to facilitate
        analysis of areas of low current. Wire identification is easily
        made using the Highlight Wire feature. When enabled, this
        highlights the selected wire and shows its end coordinates,
        connections to other wires, diameter, length, and segment length.
        Colors of all objects can be changed, and the changes kept
        temporarily or saved as new default values. You'll find operation
        of the many features to be intuitive and require little help from
        the manual. However, detailed information is included below in
        the event it is required.

        The View Antenna display can be chosen from either the Main Menu
        (selection 'VA') or the Wires Menu (selection 'V'). Operation is
        the same in both cases. When first selected, you'll see the
        antenna, coordinate axes, and other symbols, along with a menu.
        When first viewed, the antenna will be scaled and placed on the
        screen so that the coordinate system origin (x,y,z = 0,0,0) is at
        the intersection of the axis lines. If the antenna is small and
        high, you may not be able to see much detail. This is easily
        overcome, however, by using the Center Ant or Zoom features. Any
        changes you make to the display will remain until you recall a
        new description. When this is done, the new antenna is scaled and
        placed on the display, and zoom and positioning features are
        returned to their original states. Color changes remain, however,
        until you reset them or end the program. You can make the color
        choices permanent if desired, so that they are used each time you
        start the program.

        A note regarding the axis lines: When View Antenna is first
        chosen or a new antenna description recalled, the intersection of
        the axis lines is at the coordinate system origin (x,y,z =
        0,0,0). However, the antenna center or antenna shift features
        will move the origin relative to the axis lines. Two aids are
        included to remind you of the origin position. One is the origin
        marker which always remains at the coordinate system origin. It
        may be off screen in some circumstances, however. The other is
        that the axis lines are solid when their intersection is at the
        origin, and dashed when not. Use these aids to help keep track of
        the relationship among the antenna, the origin, and the axis
        lines.

        Important note: Although the View Antenna display will allow you
        to change the size, position, and orientation of your view of the
        antenna, no View Antenna operation will modify the antenna
        description itself. That is, it is not possible to change the
        antenna description in any way by using the View Antenna
        features.


                                       108




        Following is a detailed description of the features.

        Arrow keys : Rotate

        The arrow keys will rotate the display. If you rotate the antenna
        to a confusing orientation, you can always return to the default
        position by pressing 'R'.

        + - : Zoom

        The antenna can be zoomed (magnified or reduced) by pressing the
        + or - keys. The center of the zoom area is always the
        intersection of the axis lines. If you want to see more detail
        about a particular part of the antenna, use the X, Y, Z and
        <CTRL>-X, Y, Z keys to move that part of the antenna to the
        intersection of the axis lines, then use the zoom feature ('+')
        to magnify. 'R' will restore zoom to its initial value. Note to
        notebook computer users: You can use the "+/=" key with or
        without <SHIFT> to magnify, and the "_/-" key to reduce.

        <C>+ - : Zoom currents

        Pressing <CTRL> and numerical keypad + or - at the same time will
        zoom the currents without affecting the rest of the display. This
        is useful in magnifying areas of low current to see more detail.
        Note to notebook computer users: The compiler used for EZNEC
        doesn't detect <CTRL> with the "+/=" key, so use <ALT>-"+/=" and
        <ALT>-"_-" instead.

        C : Ctr ant image

        'C' centers the antenna image around the axis line intersection
        and rescales it. This is particularly useful to see more detail
        on, for example, an antenna which is at a considerable height
        above ground. Note, however, that EZNEC considers all wires in
        the description  to be part of the "antenna", so you still may
        not see much detail in, for example, a Yagi-tower model. In that
        case you would have to use the Zoom and Antenna Shift features to
        see more detail. (Single-segment wires connected to transmission
        lines are the only wires not used for View Antenna scaling.) The
        centered and uncentered displays independently move and zoom but
        rotate together. Unless no movement of the antenna image is
        required for centering, the axis lines will become dashed when
        you press 'C' to indicate that their intersection is no longer at
        the coordinate system origin.







                                       109




        D : Seg dots, axes

        This turns on and off display of the axes and the dots which show
        the segment junctions. Combinations of the two are obtained by
        pressing 'S' multiple times. Wire connection dots are turned on
        and off with the segment junction dots.

        H : Highlight wire

        This feature is useful to identify a misplaced wire as well as
        for other purposes. It also gives information about each wire.
        After pressing 'H', the menu will be replaced by a display
        showing a wire number, and the coordinates, end connections,
        diameter, length, and segment length of the wire. You can select
        a wire either by using the up and down or right and left arrow
        keys or by entering its number. As in the Wires Menu, it's not
        necessary to press <ENTER> after entering the number if there are
        fewer than ten wires. The selected wire will be a distinctive
        color which you can change if desired with the 'O' selection in
        the View Antenna menu. Although highlighting may not occur with
        some monochrome monitors, the numerical information in this
        display can still be very useful.

        I : Currents on/off

        Pressing 'I' toggles the current display on and off. Current
        magnitude is indicated by the distance of the line from the
        associated wire. This display defaults to ON when you start the
        program or recall a new antenna description. Currents must be
        calculated by normal EZNEC operation before they can be shown in
        the View Antenna display. If the currents haven't been
        calculated, you'll briefly see a message to that effect at the
        top of the screen.

        <C>-I : I phase

        (This choice isn't shown on the menu if currents haven't been
        calculated or if the current display is off.) Current phase
        information is shown by pressing <CTRL> and 'I' at the same time
        when the current display is on. Phase is indicated by rotation of
        the current line around the wire. The best way to interpret phase
        information is by turning on the phase indicators by pressing
        <CTRL>-I a second time. Phase markers consist of two lines, one
        solid and one broken. The solid line indicates the direction of
        zero phase angle; the broken line shows the direction of +90
        degree phase. Phase information is useful in determining that
        certain kinds of antennas are acting as expected. A good example
        is the 4SQUARE antenna on the disk. With the current phase
        information on, you can readily see the phases of element
        currents. In a long wire antenna, you can see the phase advance


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        along the antenna as indicated by the current line spiraling
        around the wire. In many cases, however, the phase information
        will obscure what the current magnitude is doing, so this feature
        defaults to off whenever you start the program or recall a new
        description.

        L: Trans lines on/off

        This selection toggles the display of transmission lines on and
        off. It doesn't affect the display of shorted or open stubs.

        M or F1 : Menu on/off

        Either of these keys will turn the menu on and off. Turning the
        menu off will give a wider viewing area and more uncluttered
        screen. When the menu is off, no indication is shown on the
        screen about how to turn the menu back on. Remember when you turn
        it off that the same key will turn it back on.

        O : Select cOlors

        (If you chose a monochrome or LCD monitor with EZSETUP, this
        selection isn't available or shown on the menu.) Pressing 'O'
        will replace the normal menu with a color selection menu. Select
        the item with the up and down arrow keys, and color with the left
        and right arrow keys. The colors you have chosen will remain
        until you exit EZNEC or press 'A' (Reset All). If you select 'M'
        (Make Permanent) when the color menu is active, your color
        choices will be saved in the ELNEC.CFG file and become the
        default colors.

        P : Print

        This key causes the display to be printed. You're asked to
        confirm the choice so you can avoid printing if the key was
        accidentally pressed. A "beep" indicates that EZNEC is finished
        sending the plot to the printer and that you can resume normal
        operation. This feature is disabled and doesn't appear on the
        menu when colors are reversed (see selection V,<C>V).

        R, A : Reset (All)

        'R' resets the rotation, display shift, antenna shift, and zoom
        to restore the display to its original orientation and
        magnification. If you have chosen to center the antenna ('C'),
        the position and magnification of the uncentered display won't be
        affected and vice-versa. Both centered and uncentered displays
        will be rotated to the default orientation. 'A' does the same,
        but also resets colors which have been changed and not made
        permanent, and sets all features to their default states. 'A'


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        resets both centered and uncentered displays.

        <C>-S : Uncon ends on/off

        Pressing <CTRL> and 'S' at the same time turns the unconnected
        end markers on and off. These are most useful at spotting an
        unconnected end in a group of wires connected to a common point.
        If one is spotted, choose Highlight Wire ('H') and scroll through
        the wires connected to the junction until you see one with no
        connection shown at the end in question.

        T : PaT o/solid/o

        If the pattern has been calculated, pressing 'T' turns on the
        display of the 2D far-field pattern (trace) or a "slice" of a 3D
        pattern. Pressing it a second time makes the pattern semi-solid,
        which particularly helps in interpreting azimuth plots made at
        other than zero elevation angles. A third press of 'T' turns the
        pattern display off. Please note that to speed rotation and other
        movement, EZNEC doesn't attempt to always correctly show which
        line is closest to the viewer. This may occasionally result in a
        display which shows a seemingly impossible relationship between
        the images of the antenna and the pattern, particularly when the
        pattern is semi-solid. However, the primary purposes for
        presenting the pattern in this display are to show the pattern
        shape and how it's oriented relative to the antenna, and these
        are always correct. A pattern must have been calculated by normal
        EZNEC operation before it can be shown on the View Antenna
        display. If it hasn't been, a message to that effect will briefly
        appear when you press 'T'.

        If a 3D Plot Type has been calculated, you can select the pattern
        "slice" to superimpose. See <C>(arrow keys) below.

        V,<C>V: Reverse colors

        EZNEC has the ability to reverse the plot colors to allow
        inserting the plot into a Windows document. (See RUNNING EZNEC
        UNDER WINDOWS, p. 26.) Two options are available. 'V' makes black
        white and all other colors black. <CTRL>-'V' makes black white
        and leaves all other colors unchanged. To restore colors to
        normal, press 'V' or <CTRL>-'V' again. Normal printing with the
        'P' key is disabled while the colors are reversed.









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        X,Y,Z : Move ant image+

        This feature will move the display of the antenna in the positive
        direction along an axis. It does not alter the antenna
        description. That is, the antenna is not actually being moved;
        only the display is. This feature is provided so you can see more
        detail in some part of the antenna. To do so, use this feature to
        move the portion of interest to the axis line intersection, then
        use Zoom to magnify it. (Zoom is always centered at the axis line
        intersection.) When you use this feature, note that the axis
        lines become dashed to indicate when their intersection is no
        longer at the coordinate system origin.

        <C>XYZ : Move ant image-

        Pressing the <CTRL> key with 'X', 'Y', or 'Z' moves the antenna
        image in the negative direction along an axis. See the preceding
        paragraph.

        <A>XYZ : View from axis

        Pressing <ALT> with 'X', 'Y', or 'Z' moves your viewing position
        in line with the +X, +Y, or +Z axis.

        <F2> - NoFlash on/off

        View Antenna is normally shown with VGA resolution. Each time the
        display is changed, the screen must be erased before redrawing
        the new view. This may cause a "flashing" of the display, which
        is particularly noticeable when the trace is being shown in semi-
        solid form or the description is very complex. (You may not
        notice this if you have a fast video card and bus.) The flashing
        can be eliminated by making use of multiple screen "pages", a
        feature not readily available with VGA resolution and the
        compiler used. Flashing can be eliminated at the expense of lower
        EGA resolution by pressing <F2>. Pressing the key again will
        return the display to VGA resolution. This has no effect on the
        resolution of any other menu or display. However, printing of the
        View Antenna display will be done with the resolution currently
        being used, so you may wish to restore VGA resolution before
        printing.

        Note that when the trace is shown and a 3D plot has been
        calculated, the menu selection showing "slice" selection and the
        display of which "slice" has been selected won't appear when
        NoFlash is on. This is because of the reduced number of menu
        lines available. See <C>(arrow keys) below.





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        <ESC>

        If colors are reversed, the <ESC> key restores them. Otherwise,
        it returns you to the Main or Wires Menu.

        <C>(arrow keys)

        This selection appears only when a 3D plot has been calculated
        and the Trace has been turned on with selection 'T'. When these
        conditions are met, pressing <CTRL> and an arrow key at the same
        time change the displayed plot "slice" type and angle or bearing.
        Operation is the same as for the 2D Pattern Plot -- see p. 103
        for a description. The "slice" type and angle or bearing are
        shown below the menu. If using an EGA adapter or when "NoFlash"
        (see selection 'F2') is on, neither this selection nor the
        "slice" type and angle appear due to lack of room in the menu
        area. However, the slice can still be changed.

                          The SWR Graph Display and Menu

        The SWR Graph shows, in both graphical and numerical form, the
        SWR at each source over a range of frequencies. In addition,
        source impedances are shown in numerical form. For setting up the
        frequency range and starting the plot, see selection 'SW' in "The
        Main Menu" section beginning on p. 74.

        The SWR for a given source is the SWR which would appear on a
        transmission line if the source were connected to the antenna
        with that transmission line. For example, suppose you analyze a
        Yagi antenna with a source in the middle of the driven element.
        EZNEC tells you that the SWR at that source is 2.1 (with Z0 = 50
        ohms). If you build the Yagi and connect your transmitter to the
        center of the driven element with a 50 ohm transmission line, the
        SWR on the line will be 2.1:1 (within the accuracy of the
        analysis, of course). EZNEC allows you to specify a second
        impedance for SWR output, selected with 'SZ' in the Main Menu. If
        you wanted to feed your Yagi with 75 ohm cable instead of 50 ohm,
        you could set the alternate Z0 to 75 ohms (actually its default
        value) to find what the SWR would be if 75 ohm cable were used.

        The SWR graph does no extrapolation or curve fitting.
        Interpolation consists only of straight lines drawn between
        calculated data points.

        Source impedances which have a negative resistance are shown
        numerically as "undefined" and on the graph as infinite.

        No color selection is available. The cursor is the same color as
        for 3D Pattern Plot and View Antenna and can be changed from
        either of those displays.


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          (left, right arrow keys): Cursor pos

        Pressing the left and right arrow keys position the cursor.

          (up, down arrow keys): Select source

        This selection appears only if the antenna contains more than one
        source. These keys select the source.

          F: Chg freq range

        This allows you to select a narrower frequency range for the
        graph. No extrapolation is done; only calculated points are
        shown.

          M or F1: Menu on/off

        Toggles the menu display on and off. The cursor is turned off
        with the menu.

          P: Print

        Functions the same as for the View Antenna display. See p. 111.

          V, <C>V: Reverse Colors
          
        Functions the same as for the View Antenna display. See p. 112.

          Z: Chg SWR Z0

        Toggles between 50 ohm Z0 and the alternate Z0 chosen with Main
        Menu selection 'SZ'.

          <ESC>

        If colors are reversed, restores colors to normal. Otherwise,
        returns program to the Main Menu.

                            The Near Field Setup Menu

        For more information about using Near Field results, and when to
        use Near Field analysis, see "Near Field", p. 63; NEAR FIELD /
        FAR FIELD ANALYSIS, p. 61; and DISCLAIMER, p. 9.

        Selection 'NS' in the Main Menu brings up the Near Field Setup
        Menu. This allows you to specify near field analysis type and the
        locations in space at which the near field strength will be
        computed. The field type, E or H, is changed by pressing 'F'. The
        coordinate system is switched between spherical and Cartesian by
        pressing 'C'. Note that the output from the near field analysis


                                       115




        will show locations in Cartesian coordinates regardless of which
        coordinate system was selected in this menu. This is done to
        remain consistent with normal NEC operation. Spherical
        coordinates are distance from the origin, zenith angle (angle
        downward from the z axis), and azimuth angle (angle CCW from the
        x axis in the xy plane).

        Pressing any key other than <ESC>, 'C', or 'F' will activate the
        cursor. Data entry is done in the same way as for the other
        menus. A step value of zero will result in a single step. The x
        coordinate or distance is stepped in the inner loop, followed by
        the y coordinate or zenith angle, then the z coordinate or
        azimuth angle.

        When the cursor is turned off by pressing <ESC>, the total number
        of steps is shown.

                   Frequency Sweep and the Frequency Sweep Menu

        EZNEC's frequency sweep capability can be a very valuable tool in
        evaluating antenna performance over a range of frequencies.
        However, operation is somewhat different in the frequency sweep
        mode, so it's important to understand the operation in order to
        get the most from this feature. Note that the frequency "sweep"
        is actually discrete steps. These may be evenly spaced or, if
        read from a file, any frequencies in any order. See selection
        'FL' below.

        In non-frequency sweep operation, EZNEC calculates antenna
        impedances, currents, and pattern, and keeps the current and
        pattern information. When changes are made to the antenna, only
        necessary recalculations are done. For example, when the ground
        conductivity is changed, only the pattern is recalculated. This
        is not the case with frequency sweep. It's not practical to keep
        all the information for all frequencies, so final calculation
        results are written into an ASCII file after each frequency step.
        Data present in arrays are erased and EZNEC is reset before
        beginning calculations at the next frequency. Therefore,
        calculation results from a frequency sweep are available only in
        the form of the file containing the data. (In addition, a trace
        may be saved for each frequency.)

        Three or four outputs are available from the frequency sweep.
        MicroSmith files and data output are always available for
        selection; far-field patterns (traces) are available only when
        far-field analysis is chosen for frequency sweep. You can choose
        to have EZNEC save any combination of these. SWR data are always
        saved, regardless of the outputs you choose to keep. The
        resulting data are used for the SWR Graph, and reside in a comma-
        delimited ASCII file named "LASTZ" in the current directory. The


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        file remains after the program ends and may be used for other
        purposes if desired.

          Far-field patterns (traces)

        Only 2D far-field patterns are saved during a Frequency Sweep.
        They are saved in the same form as traces saved from the 2D
        Pattern Plot Menu. However, they have the distinctive extensions
        .G1, .G2, etc. to identify which frequency step generated them.
        They are shown all together at the end of the frequency sweep,
        and can be recalled at any time afterward in the same way as any
        other trace. They are saved in the .EZ file directory (declared
        in the Options Menu) unless you specify otherwise.

          MicroSmith files

        MicroSmith is a program which enables you to see impedances on a
        Smith chart display and to design networks to match antenna
        impedances. See MICROSMITH, p. 130, for more information about
        this program. EZNEC generates both .DAT and .GAM files for this
        program from the source #1 impedance data. Note that files are
        generated only for source #1. The files are saved in a directory
        specified in the Options Menu. This normally is the directory
        containing the MicroSmith program. Please refer to your
        MicroSmith manual for the use of these files. MicroSmith versions
        2.000B and earlier were able to handle only eight frequency steps
        in imported .DAT files, while later versions can handle many
        more. EZNEC has the ability to set the maximum number of steps
        recorded in the .DAT file to work with the version you have. See
        RUNNING EZSETUP (p. 20) for information about setting this limit.
        The .GAM file may be of use to some users who don't have
        MicroSmith. The first line is the reference impedance. The
        remainder of the lines are sets of frequency (MHz), reflection
        coefficient magnitude, and reflection coefficient phase.

          Data output file 

        The data output file contains any combination of the following
        which you choose: tabular pattern data, source data (including
        SWR), load data, currents, and pattern analysis. The combination
        you choose is calculated at each frequency and written into the
        data output file. This file is in ASCII format, and is formatted
        to be easily readable. After the frequency sweep is finished, the
        file can be viewed by using EZNEC's Browse feature ('BR' in the
        Main Menu) or by returning to DOS and using another application.
        It can be printed using the ordinary DOS PRINT statement. This
        file is written into the output file directory specified in the
        Options Menu.




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        Remember that if you decide later to add more items to the
        output, you'll have to repeat the entire frequency sweep.

        Data for the SWR Graph are automatically saved, regardless of the
        selections made here. Although not intended for use other than
        the SWR Graph, they are in a comma-delimited ASCII file named
        "LASTZ" in the current directory which remains after the program
        ends. It may be used for other purposes if desired.

          Using the menu

        The Frequency Sweep Menu is accessed by pressing 'FS' when at the
        Main Menu. All choices are reset when you recall a new antenna
        description or end the program. Following is a detailed
        description of the choices and what they do.

        FO - FREQUENCY SWEEP

        Turns frequency sweep on and off. Frequency sweep is turned on
        automatically when you enter start, stop, and step frequencies
        (or frequency list file name), and cannot be turned on until
        start, stop, and step frequencies (or frequency list file name)
        have been entered.

        FL - START, STOP, and STEP FREQUENCIES

        This choice serves two functions. It is used to define the range
        and steps for the frequency sweep. Or, it is used to declare the
        name of the frequency list file if this method is chosen to enter
        frequencies. For normal sweep operation, the frequency sweep
        starts at the start frequency, ends at the stop frequency, and
        steps by the specified increment. All these are entered at one
        time, separated by commas. For example, to get data at 14, 14.1,
        14.2, and 14.3 MHz, enter '14,14.3,.1' after typing 'FL'. To use
        a list of frequencies (which can be in any order and don't have
        to be equally spaced), type 'FL', then 'F', and give the name of
        a frequency input file. See THE FREQUENCY LIST FILE, p. 135, for
        more information.

        FT - FIELD TYPE

        Use this selection to choose between near field and far field
        analysis. Only one analysis type can be done in a given frequency
        sweep. The choice will make a difference only if far-field
        patterns, pattern analysis, or field strength table have been
        selected as outputs. Certain selections are available only for
        one field type or the other, as described below.





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        PN - PAT PLOT FILE NAME

        This selection is available only with far field analysis, and
        won't appear in the menu if near field analysis has been selected
        with choice 'FT'. To save far-field patterns (traces) for each of
        the frequencies, type 'PN' and enter a file name. If, for
        example, the file name is "TEST", EZNEC will save the trace for
        the first frequency in file TEST.G1, the second in TEST.G2, etc.
        All traces will be shown superimposed at the end of the frequency
        sweep run. If you have already entered a name, a prompt will give
        you the opportunity, by typing 'x', to delete the name. This
        doesn't delete the file - it just deletes the 'PN' entry and
        disables saving of the pattern plots.

        SN - MICROSMITH FILE NAME

        This entry works like 'PN', above. If you specify the name
        "TEST", for example, EZNEC will create files TEST.DAT and
        TEST.GAM and place them in the MicroSmith file directory
        specified in the Options Menu. MicroSmith can use these files to
        display the impedance of source #1 on a Smith chart. Also, they
        provide the data MicroSmith needs to provide the structure for
        you to design a matching network. Note that only information
        about source #1 is contained in these files. To obtain MicroSmith
        files for another source, you must renumber it as #1 and repeat
        the frequency sweep. The number of frequency steps which will be
        written into the .DAT file may be limited. See "MicroSmith
        files", p. 117. For more information about MicroSmith, see
        MICROSMITH, p. 130.

        FN - FREQ SWP FILE NAME

        If no name is specified, no output data from the frequency sweep
        will be saved (except patterns and MicroSmith files if selected).
        If you want EZNEC to save tabular pattern data, source or load
        data, currents, or pattern analysis, you must enter 'FN' and
        specify a file name. None of this information will be available
        after the frequency sweep unless you have specified with choice
        'SF' that it is to be saved in the output file. After entering a
        file name, choice 'SF' will appear on the menu. Enter 'SF' to
        choose what data you want EZNEC to put into the file. The
        frequency sweep output file can have any name permissible by DOS
        and it will be placed in the output file directory specified in
        the Options Menu.








                                       119




        SF - SAVE IN FREQ SWP FILE

        This choice will appear in the menu only if a file name has been
        specified for choice 'FN', above. After entering a frequency
        sweep file name with selection 'FN', type 'SF' to choose what
        data will be written by EZNEC into the data output file. You will
        see a cursor to the right of the choices. Pressing the space bar
        will make a check mark or selection appear at the cursor
        position. Pressing it again will remove the check mark or change
        the selection. Use the up and down arrow keys and space bar to
        select the items you want to save, then press <ESC> when
        finished. Source data, load data, currents, and pattern analysis
        are the same data you see when you type 'SD', 'LD', 'CU', and
        'AN' from the Main Menu when not in Frequency Sweep mode. Field
        strength table - Far field pattern is the same as Main Menu 'TA'.
        Field strength table - Near field is the same as Main Menu 'NF'.
        The pattern analysis choice isn't available when near field
        analysis has been selected, and the options available for the
        field strength table are different for near and far field
        analysis. When you first run a frequency sweep you might specify
        a run with only a few frequencies and have EZNEC save all the
        items to get an idea of what sorts of data they contain.

        Data for the SWR Graph are automatically saved regardless of the
        selections made.

        DElete freq sweep file

        You can use this selection to delete a frequency sweep file or
        any other file in the output file directory. You can also use it
        to delete any other file by specifying the full path along with
        the file name.

        BRowse freq sweep file

        This works the same as the Browse function in the Main Menu. See
        "The Main Menu", p. 74, for more information.


                                    GROUP EDIT

        The Group Edit feature may be used in the Wires, Sources, Loads,
        and Transmission Line Menus. It permits adding, deleting, moving,
        or copying groups of wires, sources, loads, or transmission
        lines. It also allows entering a common value for one of the
        parameters of a group of any of these items. All special editing
        features, such as changing wire length or rotating wires, are
        available in the Group Edit Modify mode. A special feature in the
        Wires Menu permits changing the X, Y, or Z coordinate of a group
        of wires. Despite the lengthy explanation below, Group Edit is


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        easy to use by simply following the instructions given by the
        prompts. A few minutes of experimentation will be very helpful in
        understanding how the operations work. The Wires Menu will be
        used for the following examples, but most operations except X, Y,
        and Z work the same way for all menus. Special cases for various
        menus are described at the end of this section. Note that
        shortcut add and delete functions are also available from the
        menus without entering the Group Edit mode.

          Starting Group Edit and selecting a group of items

        Group Edit is started by typing 'G' from the Wires, Sources,
        Loads, or Transmission Lines Menu. After selecting, more choices
        are shown at the bottom of the screen. Adding and deleting are
        self-explanatory. Copying is useful in modeling stacked antennas
        or for duplicating a complex element, and for making multiple
        copies of complex sources or loads. Moving groups won't affect
        results but may be helpful in putting items in a more logical
        order. The mOdify choice permits you to fill a group of cells
        (for example, the diameter of a group of wires) with the same
        value or to perform the special editing features on a group of
        wires. (See "Modifying items", and "Special Notes: Wires Menu",
        below.)

          Adding: Entering how many

        If you chose Add, you'll be asked how many to add, then will be
        asked for a destination. Skip the next paragraph and go to the
        section on selecting a destination.

          Copying, Deleting, Moving, mOdifying: selecting a group

        After choosing the action, you must choose the range of wires
        (for example) on which to operate. The range can be chosen in
        either of two ways. You can either specify a range of wire
        numbers (such as '3-5' or '3,5') or you can move the cursor to
        the starting wire number, press '.' to "anchor" the choice (as in
        most spreadsheets), then move the cursor to the last wire number.
        Finally, press <Enter> to finish the selection. For example, to
        choose the range 3-5, move the cursor to wire 3, press '.', move
        the cursor to wire 5 (note that wires 3-5 are now highlighted),
        and press <Enter>. If the second number is greater than the
        highest wire number, it will be interpreted as being the highest
        item number. You can select all wires by entering 'A'. If
        deleting wires, this completes the action except for confirming
        that you want to delete. Skip the next step if modifying items.






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          Adding, Copying, Moving: selecting a destination

        What happens next depends on whether you initially selected
        mOdify or some other action. If the selection was other than
        mOdify, you'll be asked for a destination. You can enter a single
        number, or move the cursor until the box on the left is on the
        wire number following the desired destination point and press
        <Enter>. For example, to put copies of wires 1-3 into the list
        following wire 5, select 1-3 for the group as described in the
        previous paragraph. For the destination, enter '5' followed by
        <Enter>.

          mOdifying items

        If you selected mOdify, only one column will be highlighted, and
        you can select the column with the arrow keys. As you position
        the highlighted area in different columns, your choices will
        appear at the bottom of the screen. These are the same choices
        you have when entering data in the non-group mode. For example,
        to change the diameter of the selected wires to one unit, move
        the highlighted area to the Dia column, enter '1', then <Enter>.
        When finished entering values, press <ESC>. Note that in the
        Modify mode, all the powerful normal editing features are
        available. For example, you can rotate or change the lengths of
        all the selected wires at once. Or if you select a group of wires
        and enter ',,15', the z coordinates of all the selected wires
        will be changed to 15, but the other coordinates will remain the
        same.

          Special Notes: Wires Menu

        The example at the end of the preceding paragraph shows how to
        change the coordinate of a group of wire ends to a value you
        specify. Choices X, Y, and Z allow you to change the coordinate
        by a given amount. After selecting the group of wires to change,
        one end of the group will be highlighted. Select the wire end to
        change, then enter the amount you want the X, Y, or Z coordinate
        to change. If you want to reposition the wire, repeat on the
        other end.

        If you move a group of wires, sources, loads, and transmission
        lines on the wire will be moved with them. If you delete a group
        of wires containing sources, loads, or transmission lines, you'll
        be warned that they'll be deleted before the action is final. If
        you copy a group of wires which contain sources, loads or
        transmission line stubs, you can choose to also make copies of
        the sources, loads, and transmission line stubs at the same
        positions on the new wires.

        The Delete option won't appear if there's only one wire.


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          Special Notes: Sources Menu

        Since no more than one source can be placed at the same place on
        a wire, copies of sources will be assigned to "wire 0". You must
        assign them to legitimate wires before exiting the Sources Menu.

        The delete option won't appear if there's only one source.


                      SAVING, RECALLING, AND DELETING FILES

        When saving, recalling, or deleting a file, EZNEC will show you a
        list of the appropriate files. The directory which is shown is
        determined by the default paths you selected in the Options Menu.
        The path for output files is the directory shown for Browse and
        data output (currents, source data, load data, pattern table,
        analysis, and frequency sweep) operations. The .EZ path is the
        default for antenna descriptions and far field patterns (traces).
        The path chosen for frequency sweep MicroSmith file outputs is
        the default for MicroSmith file operations. Other file operations
        will default to the current (EZNEC program) directory. If the
        list is too long to fit on the screen at once, you can scroll the
        display by using the up and down arrow keys and <PgUp>, <PgDn>,
        <CTRL>-<Home>, and <CTRL>-<End>.

        A very convenient feature is the file list "wild card"
        capability. "Wild cards" are the characters "*" and "?", which
        substitute for any number of following characters and a single
        character, respectively. If you specify a file name which
        includes a "wild card" character, EZNEC will show all the files
        with that specification. For example, 'vert*' will show all files
        in the .EZ file directory beginning with "VERT" and having an
        ".EZ" extension , e.g., VERT.EZ, VERTICAL.EZ, VERT1.EZ, etc.
        Specifying a "wild card" character when deleting files will NOT
        delete all files with the given specification; they will only be
        listed as described above. You can see what .EZ files there are
        in another directory, say \OLDANTS, by typing '\oldants\*' at the
        prompt. If this is done, the specified directory will become the
        new assumed path for any file name you enter.


         SAVING, RECALLING, COMBINING, AND DELETING ANTENNA DESCRIPTIONS

        See the section immediately above for additional information.

        When you recall an antenna description, you are shown an
        alphabetized list of the description files in the directory
        specified in the Options Menu. ELNEC (.EN) and EZNEC (.EZ) files
        are shown.



                                       123




        To choose a description to save, recall, or delete, type its name
        at the prompt. If you don't type an extension, EZNEC will load
        the file with that name and an .EZ extension. If it doesn't find
        one, it will load the file having that name and an .EN (ELNEC
        format) extension and convert it. It's not necessary to type the
        path or directory for the file names shown on the screen; the
        correct path will be added by EZNEC. The extension ".EZ" will be
        added to antenna description files you save if you don't specify
        an extension. Only ".EZ" will be accepted as an extension for
        saving a file if you do specify one. For compatibility with
        earlier versions, you may recall or delete files with any
        extension.

        Antenna descriptions can easily be combined. Specify 'RE' as for
        recalling a description file. When giving the file name, precede
        it with '+'. (A reminder appears at the bottom of the screen when
        recalling descriptions.) This will cause the wires, sources,
        loads, and transmission lines of the "recalled" file to be added
        to the present description. It will have no effect on the
        frequency, media, or other parameters.

        This feature shouldn't be confused with EZNEC's ability to import
        wires from an ASCII file. For more information on the IMPORT
        feature, see "Import wires" on p. 90.


                     USING THE NEC BURIED GROUND RADIAL MODEL

        If you would like to use the NEC buried ground radial model,
        please first read this section very carefully. This section deals
        only with the NEC ground radial model available in the Media
        Menu, not the "Create Radials" feature in the Wires Menu or
        radials modeled as wires.

        The NEC buried ground radial model is similar to the model used
        in ELNEC and MININEC. It is not actually a model of buried wires,
        and it does not model the effect of ground radials on antenna
        impedance, current, loss, or efficiency. It does approximately
        model the effect of ground radials on the pattern, an effect
        which is generally slight, unless ground radials are very long.

        The NEC buried ground radial model is available only for Real,
        "Fast analysis" (reflection coefficient) ground.

        The effect of the NEC buried ground radial model on feedpoint
        impedance is different than the effect of a real radial system on
        a real antenna. The presence of any radials at all, even one very
        short radial, will change the NEC-calculated ground connection
        resistance to zero, but only at the point (x, y, z) = (0, 0, 0).
        Experiments have shown this to not always be true when wires


                                       124




        connect to ground at a sloping angle. The resistance of
        connections to ground at other points will have an unpredictable
        resistance, as they do without the radials. This means that the
        model radials won't accurately predict the input impedance of a
        grounded wire such as a vertical antenna. The buried ground
        radial model is used only for calculation of ground reflection
        coefficients for the patterns. Even for this limited use, the
        buried radial model isn't accurate unless there are many radials.
        The conductivity of the radials is "peanut-buttered" over the
        entire ground area that the radials cover (varying with distance
        from the origin), and the result is simply paralleled with the
        ground conductivity in the region where the radials are placed.
        Four radials simply look like thinner "peanut butter" than 120
        do.

        Once again, the model radials do not represent a true picture of
        the effect of real ground radials, and must be used only with
        great care.

        Before it can be used, the NEC buried radial model feature must
        be enabled by means of environment variable EZRO. See ENVIRONMENT
        VARIABLES, p. 136, for instructions.

            Adding or Changing Radials in the NEC buried radial model

        If the NEC buried radial model is enabled, radials are entered
        and modified from the Media Menu (p. 99). Several conditions must
        exist before the radial selection occurs in the menu. There must
        be two media and a radial boundary. Real, Fast-analysis ground
        must have been chosen in the Main Menu. And the radial capability
        environment variable must have been set as explained immediately
        above. When these conditions are satisfied, selecting 'R' in the
        Media Menu brings up a small display near the bottom of the
        screen showing the number of radials and the diameter of the
        radial wires. Note that the wire diameter might be in different
        units than coordinates and boundaries. If desired, the diameter
        may be entered as wire gauge (AWG) by typing '#--' where "--"
        represents the wire gauge. Gauges of wires larger than #0 (i.e.,
        #00) are not permitted. When you are finished with radial entry,
        press <ESC> to return to the Media Menu. The radials extend to
        the outer edge of the first medium, so the radial length is
        changed by changing the radial boundary of the second medium. 










                                       125




                                    TRACEVIEW

                                Starting TraceView

        The TraceView mode is a way to look at, compare, or print saved
        traces without having to run a far-field analysis. Trace View
        mode is also capable of displaying some plot files in the OpenPF
        standard format generated by programs other than the EZNEC
        family. See p. 131 for more information about OpenPF. To use
        TraceView, start EZNEC by typing 'EZNEC TV'. The first thing
        which must be done is to select a "primary" trace. Either a 2D
        plot (extension .PF, .G#, .ENT, .F#) or 3D plot (extension .PF3)
        can be selected. (TraceView is the only way to display a saved 3D
        plot.) The primary trace plays the same role as the calculated
        trace in EZNEC's normal mode. ANALYZE is done (in the 2D display)
        on the primary trace. The primary trace also determines the
        initial value of the plot outer ring if automatic scaling is
        chosen, and an abbreviated description under the printed 2D plot
        will contain information about the primary trace. EZNEC will
        begin the TraceView mode by showing a list of the saved trace
        files. You can choose from this list or enter a file name from
        another directory (See SAVING, RECALLING, AND DELETING FILES, p.
        123). You may also return to the Main Menu and choose another
        directory with the Options Menu. Until a primary trace is chosen,
        EZNEC will only let you recall a trace, go to the Options Menu,
        or quit the program. After a primary trace is chosen, the program
        returns to the Main Menu. Note that most of the normal selections
        aren't available. This is because EZNEC doesn't do any
        calculations or antenna modifications in TraceView mode -- it's
        strictly for showing existing traces. <Enter> will plot the
        primary trace. You can print the plot or recall additional traces
        just like you do in EZNEC's normal mode.

        EZNEC has a limited ability to display non-EZNEC plot files in
        the standard OpenPF (extension .PF) format. See p. 131.

                            Changing the Primary Trace

        You can select a new primary trace by selecting 'RT' (Recall
        Trace) from the Main Menu. This selection appears only in
        TraceView mode. You can choose either a 2D or 3D trace as
        described above. If you don't specify an extension, EZNEC will
        look for a standard 2D file of that name with a .PF extension. If
        not found, it will next look for an ELNEC/EZNEC v. 1 2D trace
        file (.ENT extension). Finally, it will search for a 3D file
        (extension .PF3). You can, of course, specify any of these
        extensions, in addition to .F# or .G#, when you give the file
        name.




                                       126




                                 Ending TraceView

        When you exit TraceView by selecting QU (QUit), the LAST.EZ file
        is not altered.


                                   EZNEC FILES

        The only EZNEC files which are intended to be readable by users
        are  README.TXT, ANTNOTES.TXT, EZNEC.BAT, EZNEC.VER, and outputs
        which can be "printed" to a file (frequency sweep output; and
        source, load, current, pattern analysis and near and far field
        pattern table data). MicroSmith .DAT and .GAM files are ASCII
        format, but have no explanatory information. NFTEXT and ERRTEXT
        are ASCII format but are intended only for program use. (NOTE:
        Any modification of NFTEXT will result in the inability to run
        near field analysis. Modification of ERRTEXT will result in
        incorrect or missing error or information messages.) Most other
        files are binary and are unreadable with ASCII viewers.

                        Files on the Distribution Disk(s)

        INSTALL.EXE:       EZNEC installation program.
        EZPGM.EX_:         Compressed program files EZNEC.BAT,
                           EZMAIN.EXE, EZCALC.EXE, and others.
        EZDESC.EX_:        Compressed antenna description (.EZ) files
                           (described below). 
        README.TXT:        Contains instructions for printing this
                           manual, additions and corrections to the
                           manual, and other information.
        EZNEC.VER:         Gives the exact EZNEC version number. The last
                           one or two digits are the revision level due
                           to minor changes. INSTALL uses the presence of
                           this file to locate the installation program
                           during installation.
        EZNEC.TXT          This manual.
        ANTNOTES.TXT       Notes describing the example antenna files.

        File compression is done under license to PKWARE, Inc.

        The following files must all be present and in the same directory
        for EZNEC to run properly. Except as noted, these are installed
        by INSTALL:

        EZMAIN.EXE:        This is the interface portion of EZNEC.
        EZCALC.EXE:        NEC-2 calculating engine.
        EZNEC.BAT:         The batch file which operates EZNEC.
        ERRTEXT:           Contains information and error messages. Do
                           not modify this file.



                                       127




        NFTEXT:            Used by the program for Near Field analysis.
                           Modifying this file will result in inability
                           to run Near Field analysis.

        The remainder of the files improve program operation or are
        useful in other ways:

        INTERACT.INI:      Provides initialization variables for EZCALC.
                           The presence of this file can greatly speed
                           loading of EZCALC. Do not modify this file.
        LF90.EER:          Provides a meaningful error message in the
                           unlikely event of a crash of EZCALC. Not
                           essential for EZNEC operation.
        EZSETUP.EXE:       The program setup file. Writes or modifies
        ELNEC.CFG.
        EZNEC.TXT:         This manual
        ANTNOTES.TXT:      Contains notes about the furnished example
                           antenna description (.EZ) files.
        OPENPF.TXT:        Contains a full description of the OpenPF plot
                           file standard.
        .EZ  files:        These files contain antenna descriptions, and
                           may be saved, recalled, and deleted from the
                           Main Menu. Whenever you save an antenna
                           description, it is given the extension ".EZ"
                           and stored in the subdirectory specified in
                           the Options Menu unless you specify another
                           directory when you save it.
        LAST.EZ:           This antenna file contains the description of
                           the last antenna analyzed. It's read when
                           EZNEC is started, and the antenna description
                           present when EZNEC is quit is written into
                           this file. (Exception: If EZNEC is ended by
                           selecting 'EX' from the Main Menu, LAST.EZ
                           isn't changed.)

                      Files Created by EZNEC and/or EZSETUP

        .GAM, .DAT files:  These are files written in a special format
                           for use by the MicroSmith program. See
                           "Frequency Sweep and the Frequency Sweep
                           Menu", p. 116, for more information. They are
                           written to a directory specified in the
                           Options Menu.
        ELNEC.CFG:         This file is created by EZSETUP, EZNEC, or
                           INSTALL when run the first time unless it's
                           already present in the program file directory.
                           It contains all options chosen with EZSETUP
                           and the EZNEC Options Menu. Each time EZNEC is
                           started, it looks for this file in the current
                           directory, reads it, and uses the values it


                                       128




                           finds. If ELNEC.CFG isn't found, EZNEC creates
                           it with default values. ELNEC.CFG is modified
                           by running EZSETUP, choosing 'MP' in the
                           Options Menu, or 'M' in the View Antenna color
                           selection menu. ELNEC.CFG is shared with the
                           earlier MININEC-based program ELNEC. See
                           RUNNING EZSETUP, p. 20, and "The Options
                           Menu", p. 82, for more information.
        LASTZ:             Created when Frequency Sweep is run or the SWR
                           Graph is displayed. Contains, in comma-
                           delimited ASCII format, the impedance and SWR
                           at each source and frequency. Remains after
                           program ends and can be used for other
                           purposes if desired.
        .PF (trace) files: These files contain 2D trace information and
                           are saved and recalled from the 2D Pattern
                           Plot Menu. They are stored in the same
                           subdirectory as the .EZ files. They are
                           written using the OpenPF standard format (see
                           p. 131).
        .PF3 files         These contain a 3D pattern in OpenPF format.
                           The data are organized as elevation "slices".
        .G(#) files:       These are 2D trace files created during a
                           frequency sweep. They have the same format as
                           .PF files. The file with extension .G1 is the
                           trace for the first frequency step, .G2 for
                           the second, etc. They can be recalled and
                           viewed like the .PF files. They are stored in
                           the same subdirectory as the .EZ and .PF
                           files.
        .ENT, .F(#) files: These are written by earlier versions of EZNEC
                           and have the same function as .PF and .G(#)
                           files. They can be read by EZNEC, but EZNEC
                           does not write files in this format.
        Ground data files: These contain interpolation files for High
                           Accuracy Real ground analysis. The
                           availability of these files prevents EZNEC
                           from having to re-calculate them each time the
                           program is run. Two versions might be present.
                           Files with extension .EG1 are written and used
                           by EZCALC, the calculating engine. Ground
                           files left from older versions of EZNEC have
                           extension .EZG. These must be converted before
                           being usable by EZNEC. (See EZSETUP "Ground
                           file utilities", p. 24.) After conversion they
                           can be deleted. Ground files are saved in the
                           directory specified by EZSETUP for this
                           purpose.
        Data output files: Various outputs may be saved to a file. These
                           have names specified by the user and are


                                       129




                           written to the data output directory specified
                           in the Options Menu.
        Temporary files:   These files all begin with $NTEMP, and are
                           erased when EZNEC ends. They contain various
                           information used by EZCALC, data passed
                           between EZMAIN and EZCALC, virtual RAM data,
                           and NEC-2 impedance matrix contents. Temporary
                           files can be very large with complex
                           descriptions. They are stored in the directory
                           selected from the Options Menu.

                                    MICROSMITH

        MicroSmith, by Wes Hayward, is an inexpensive program which
        allows you to view impedances on a Smith chart. With its aid,
        impedance matching networks can be designed. EZNEC is able, in
        its Frequency Sweep mode, to write files for direct input of
        source impedance data to MicroSmith. MicroSmith is published by
        the American Radio Relay League, 225 Main Street, Newington, CT
        06111 USA, phone (860) 594-0259. Contact them directly for price
        and ordering information.


                                     PRINTERS

        Note that the printer must be connected to a parallel printer
        port. HPIB and serial buses aren't supported.

          Laser and DeskJet

        See RUNNING EZSETUP (p. 20) for more information.

          Dot matrix

        Most 8- or 9-pin dot-matrix printers can emulate an Epson FX
        printer, and most 24-pin printers can emulate the Epson LQ
        series.  Drivers are also included for the Epson MX, which has a
        smaller set of graphics density options. The 8/9 pin IBM
        Proprinter is compatible with the Epson MX for EZNEC graphics.
        The 24-pin Proprinter also can use the Epson MX driver, but only
        8-pin resolution will be available. Even if your printer can't
        imitate any of these exactly, it may respond correctly to the few
        necessary commands and work satisfactorily. If a special setup
        string is required to set the printer to an Epson emulation mode,
        it can be sent automatically. Please refer to RUNNING EZSETUP, p.
        20, for more information. If you can't make plots print
        correctly, and have tried the suggestions under PROBLEMS, your
        printer isn't a compatible type.




                                       130




                            OpenPF PLOT FILE STANDARD

        The OpenPF (.PF) plot file format standard permits the
        interchange of plots between programs. EZNEC uses this standard
        for far field plots. Because EZNEC doesn't do any processing of
        plot data, its conformance to the standard is intended primarily
        to make EZNEC plots readable by other programs which do further
        processing, rather than to make other programs' files readable by
        EZNEC. However, EZNEC is able to import some plot files for
        display, either in the TraceView mode or by recalling the plot
        from the 2D Pattern Plot Menu. Some of the limitations when
        reading plot files generated by other programs are:

          -  Only far field linear polarization data in dBi (OpenPF block
             types 1-3) can be displayed.
          -  Although a single OpenPF file can contain multiple plots
             from various orientations, EZNEC can recall only one at a
             time. If the file contains both azimuth and elevation plots,
             you will be asked which to display. If there are multiple
             azimuth or elevation plots, only the first of each can be
             displayed.
          -  Y (azimuth data) / Z (elevation data) symmetry is not
             supported. X (azimuth data)  / XY (elevation data) symmetry
             is supported.

        A conscientious effort has been made to enable EZNEC to read
        OpenPF files generated by other programs, within the above
        limitations. However, no assurance can be given that it will
        successfully read all such files. A possibility exists that
        importation of a non-EZNEC family plot will cause EZNEC to crash.
        You will be warned of this possibility when importing.

        An EZNEC .PF file contains a single azimuth or elevation plot or
        "slice". A .PF3 file contains, in standard .PF format, a partial
        3D plot organized as elevation "slices" at azimuth angles
        extending from zero degrees to (180 degrees minus the step size).
        This is enough information to construct an entire 3D plot.

        A complete description of the OpenPF standard is contained in the
        file OPENPF.TXT on the distribution disk.












                                       131




                           IMPORTING WIRE DESCRIPTIONS

        Wires can be imported from an ASCII file if desired, via
        selection 'I' in the Wires Menu (p. 85). This is not intended to
        be a substitute for EZNEC's standard system, but an easy way to
        import data generated by another program. The imported wires can
        be added to or replace the existing description, by the user's
        choice. The file format is simple, but a detailed description
        follows.

        The ASCII import file consists of an optional line defining the
        units to be used for coordinates and diameter, followed by one
        line per wire giving the end coordinates, diameter, and,
        optionally, number of segments. Comments may appear anywhere in
        the file. Tabs, spaces, commas, or any combination may be used as
        delimiters.

        The optional units specification is done on one line and must
        precede all wire definitions. If absent, wire coordinates and
        diameters are assumed to be in meters.

        Wire definitions consist of end 1 coordinates, end 2 coordinates,
        and diameter. If desired, the number of segments can be added as
        an eighth field. If the segment field isn't included, the wire
        will be automatically segmented using the"conservative" criteria.

        The file is case-insensitive. Blank lines, and any text on a line
        following a semicolon will be ignored. Blanks, commas, tabs, or
        any combination can be used as delimiters (separators between
        fields or individual specifications).

        Imported wires can be used to add to or replace an existing
        definition.

          Example:

        This is the wire configuration for the 4-square array of example
        description file 4SQUARE.EZ. Note that a complete antenna
        description must also include sources, which must be added from
        within EZNEC.

        ; Example file for EZNEC wire importing: four square array

        ; NOTE that wire import files don't contain sources or
        ; information other than wires. To actually make a 4-square array
        ; with the information from this file requires specification of
        ; sources, frequency, ground type, etc.

        ; The first non-comment line is the units specifier. This will
        ; cause:


                                       132




        ;   -- Program UNITS to be changed to FEET
        ;   -- Wire coordinates to be interpreted as being in feet
        ;   -- Wire diameter to be interpreted as being in inches

        ft in

        ; Next are the wire specifiers. Some lines use spaces and some
        ; commas to illustrate that either can be used as delimiters. As
        ; written, these wires will be automatically segmented using
        ; "conservative" density. If desired, an additional field could
        ; be added to any line to cause "minimum" recommended density, or
        ; a specific number of segments.

        ; The first three numbers are the end 1 coordinates (in feet
        ; because of the first unit specifier above). The next three are
        ; the end 2 coordinates (ft). The seventh number is the diameter
        ; (in inches because of the second unit specifier).

        0,0,0   0,0,32.75       1.5
        0 34.42 0   0,34.42 32.75   1.5
        34.42 0 0 34.42 0 32.75,1.5
        34.42 34.42 0    34.42 34.42 32.75   1.5

        ; Normally the wire specifications would be written to be easier
        ; to read. The above format was chosen to illustrate the
        ; flexibility available in choosing field delimiters.

                 Complete Rules for Wire Files Used for Importing

          General:

        No distinction is made between upper and lower case letters.

        A semicolon (;) and anything to its right on a line will be
        ignored.

        Blank lines will be ignored.

        Spaces, tabs, commas, or combination may be used as delimiters.

        There are two types of specifications: wires and (optional)
        units.

        Units specification line (optional) must precede all wire
        specifications.

        Text fields (only) can be surrounded by quotation marks (" ").
        These are coordinate units, diameter units, wire diameter
        specified as wire gauge, and "M" specifying minimum segmentation.
        Quotation marks are not required for any field.


                                       133




        The user will be given the choice of adding the wires to the
        existing description or replacing the existing description with
        the wires.

          Units Specifications:

        Zero, one or two unit specifiers may be included.

        Unit specifiers must precede all wire specifications.

        If two specifiers are given, they must appear on the same line
        and be separated by a valid delimiter.

        The first unit specifier is the coordinate unit specification. It
        will modify the EZNEC UNITS selection, and wire coordinates in
        the import file will be interpreted as being in the specified
        units. If the units specifier line is absent, all coordinates and
        diameters will be interpreted as being in meters. 

        The second unit specifier (optional) is the diameter
        specification. Wire diameters will be interpreted as being in
        these units. The units used by the program for wire diameter may
        be different than, and will not be determined or changed by, this
        specification. (For example, if both the coordinate and diameter
        units specifications are feet, EZNEC will change its UNITS to
        feet. If a diameter is given in the import file as 0.5, it will
        be interpreted by EZNEC as having a diameter of 0.5 feet.
        However, EZNEC shows diameters in inches when UNITS are feet, so
        after importing, the wire will show up in EZNEC as having a
        diameter of 6 inches.) If no diameter unit specifier is given,
        wire diameters will be interpreted as being in the same units as
        the end coordinates.

        Only the first two letters of each specifier is read. They are
        interpreted as follows:

          M  or ME         - meters (If M is used alone, it must not be
                           followed by any other character, including a
                           period.)
          MI or MM         - millimeters
          FT or FE         - feet
          IN                               - inches
          WA or WL         - wavelengths









                                       134




          Wire Specifications: 

        Wire specifications must have at least 7 fields.

        Fields are end 1 x, y, z coordinates; end 2 x, y, z coordinates;
        diameter; and, optionally in an eighth field, number of segments.
        See below for more information about the segment field. Wires
        having zero length or diameter will be rejected. Coordinates are
        interpreted as being in the units specified by the first unit
        specifier. If no unit specifiers are given, they will be
        interpreted as being in meters, not in the units currently being
        used by the program.

        Diameters are interpreted as being in the units specified by the
        second unit specifier. If no second unit specifier is present,
        they will be interpreted as being in the same units as the end
        coordinates. The diameter of any wire may be given as AWG wire
        size, using #n where n is an integer > 0. (n can have more than
        one digit.) The optional segmentation field can contain the
        number of segments for the wire or the letter "M". "M" will
        result in minimum-recommended count automatic segmentation for
        the wire. If the segmentation field is blank, or contains any
        other non-numeric value, zero, or a negative number, the wire
        will be automatically segmented using "conservative" criteria. 

        Fields beyond the eighth will be ignored.


                             THE FREQUENCY LIST FILE

        A frequency list file contains frequencies to be used for the
        "frequency sweep". Frequencies in this list don't have to be
        evenly spaced, and can be in any order. However, if you want to
        use MicroSmith with the EZNEC output, results will be much easier
        to interpret if frequencies are entered in increasing order. The
        frequency list file is specified by Frequency Sweep Menu
        selection 'FL' (see "Frequency Sweep and the Frequency Sweep
        Menu", p. 116).

                    Complete Rules for the Frequency List File

        Frequencies are in megahertz (MHz), and consist only of numbers.
        They may be in any order and do not have to be equally spaced.

        Frequencies must be separated by commas, spaces, or carriage
        returns, or a combination of these.

        Comments may be entered anywhere in the list, but may not begin
        with a number.



                                       135




        Entries of zero, or empty fields, will be ignored.

        A negative entry will terminate reading of the file. This is a
        convenient way to limit processing to only the first part of a
        lengthy list.


                                     PLOTTERS

        A request is occasionally received for a plotter driver. EZNEC
        currently creates a plot for the screen then "dumps" the screen
        data onto a printer. This can't be done with a plotter. A plotter
        requires creation of a separate, special plot just for its use.
        Because of the relative complexity of the task and the limited
        demand, plotter drivers are not and will not be available for
        EZNEC.


                              ENVIRONMENT VARIABLES

        Certain features are seldom enough changed that they weren't put
        into the Options Menu or the EZSETUP program, yet some users may
        want to make use of them. These have been addressed by having
        them controlled by an environment variable. Environment variables
        are text strings which are entered within DOS and are available
        to DOS programs such as EZNEC. Once an environment variable is
        set, it remains set until intentionally reset, or until the
        computer is turned off or rebooted. Exception: An environment
        variable set while in a Windows DOS window will be reset when the
        window is exited. More information about Windows environment
        variable use is given below.

                           EZNEC environment variables

        ENNF=ON      Forces View Antenna NoFlash state ON.
        ENNF=OFF     Forces View Antenna NoFlash state OFF.
        NOENF=ON     Suppresses showing of the ELNEC .EN files during
                     save, recall, and delete operations.
        EZRGW=OFF    Suppresses the warnings for wire connected to non-
                     MININEC real ground.
        EZEB=OFF     Turns off minor entry error beeps.
        EZRO=ON      Enables the ground radial model. (Read USING THE
                     GROUND RADIAL MODEL, p. 124 before using!)
        EZPR1=OFF    Inhibits printer "out of paper" detection, which
                     may spuriously appear in some cases when a network
                     printer is used.
        EZPR2=OFF    Inhibits all printer tests.
        EZXMS=(#)    Tells EZNEC how much extended memory (in kbytes) is
                     available, overriding the internal EZNEC test. This
                     must be assigned if EZNEC is used without a memory


                                       136




                     manager, since EZNEC's internal test requires a
                     memory manager.

          To set an environment variable:

        Type 'set' followed by the text exactly as above (case is
        ignored). Make sure there isn't a space on either side of the '='
        sign. For example, to set the View Antenna NoFlash state to ON,
        enter 'set ennf=on'. This can be typed directly at the DOS
        command line prompt, or included in a batch file. If included in
        AUTOEXEC.BAT, it will be entered every time you start your
        computer. If included in the EZNEC.BAT file (at the place
        indicated in the file), it will be entered every time you start
        EZNEC. It doesn't hurt to enter it more than once. To reset an
        environment variable, type 'set' followed by the variable name,
        and '='. For example to reset the View Antenna NoFlash variable,
        type 'set ennf='. To see what variables are set, type 'set' at
        the DOS command line.

          If the environment variable doesn't function:

        Make sure there are no spaces on either side of the = sign in the
        'set' statement, and that the environment variable is spelled
        correctly. If these aren't the source of the problem, DOS may be
        out of environment space, as described next.

        DOS doesn't leave much room for environment variables. If it runs
        out of space it will simply ignore further entries. (You may see
        the message "Out of environment space", but it may go by too
        quickly to see.) You can increase the space by adding a line to
        your CONFIG.SYS file, which looks something like
        'SHELL=C:\DOS\COMMAND.COM /E:512 /P', where C:\DOS\ is the path
        to the COMMAND.COM file. A value larger than 512 might be
        required if you have a long PATH statement in your AUTOEXEC.BAT
        file, or a large number of environment variables. The computer
        has to be re-booted for changes to take effect. See your DOS
        documentation for more information.

        Any environment variable set while in a Windows DOS window will
        be reset when the window is exited. If you want the environment
        variable to remain set between DOS window sessions, put the 'set'
        command in your EZNEC.BAT or AUTOEXEC.BAT file, or in the 
        Optional Parameters box in the PIF editor as described earlier.









                                       137




                                     PROBLEMS


          EZNEC doesn't agree with (MININEC-based) ELNEC or another NEC-2
          based program

        EZNEC and ELNEC should agree quite closely with Perfect or
        MININEC-style ground, or Free Space analysis. If they don't, here
        are some possible reasons:

        1. An inaccuracy of MININEC (ELNEC) not present in NEC-2. These
        include analysis of wires joining at an acute angle, particularly
        in parasitic antennas such as quads; and a "frequency offset"
        error noticeable when modeling long Yagis. For these cases, EZNEC
        will be more accurate.

        2. An inaccuracy of NEC-2 not present in MININEC. These include
        analysis of connected wires of dissimilar diameters and analysis
        of very small loops. Here, ELNEC or MININEC may be more accurate
        than the EZNEC NEC-2 calculating engine.

        3. Fundamental differences in source and load placement. ELNEC or
        MININEC and EZNEC may disagree where source or load placement is
        critical because of differences in how the programs place sources
        and loads. See p. 58 for more information.

        4. Use of MININEC-type ground. NEC-2 has no direct equivalent.

        5. A condition which isn't allowed with either program, such as
        wires crossing or occupying the same space. Different programs
        will react differently to disallowed configurations.

        EZNEC's NEC-2 calculating engine (EZCALC) has not been modified
        in any essential respect with regard to calculation. No case has
        been found where EZNEC results deviate substantially from NEC-2.
        The few situations in which EZNEC disagreed with another NEC-2
        based program have been ones in which very small differences in
        source placement make very large differences in impedance.
        Differences in segmentation can cause quite dramatic changes in
        source impedance when this condition exists, and are probably the
        reason for the observed disagreement. See p. 58 for more
        information about placement of critical sources.

          Source resistance is negative

        This can be a correct result for some arrays having multiple
        sources. In these cases, the resistance is generally only a few
        ohms negative. If a single-source model shows a negative
        resistance, an internal numerical calculation has exceeded its
        ability to produce accurate results. This may be due to a


                                       138




        disallowed geometry, such as overlapping wires or wires crossing
        at other than a segment junction. Attempts to model very small
        loops may also cause this problem. The only cure is to modify the
        geometry to bring the model within NEC's capabilities. This
        problem is often accompanied by an indicated field strength of -
        99.99 dBi in all directions.

          Monitor clicks, flashes, and/or blooms while EZNEC is running

        EZNEC switches from text mode to graphics mode to present the
        plots and Antenna View display. Some multi-sync monitors take two
        seconds or more to make this transition, sometimes accompanied by
        flashing, fading, or blooming. I know of no cure for this except
        to recommend a different monitor. If you find operation to be
        unsatisfactory, the only recourse is to ask for a refund of your
        purchase price within the warranty period, which will be promptly
        honored.

          Plot grid appears but no plotting apparently takes place:

        This can be caused by wires crossing or occupying the same space
        or an attempt to model a small-diameter loop antenna (see p. 51).
        This is frequently accompanied by an indicated negative source
        resistance. Or you may be plotting the pattern in a direction in
        which the field intensity is very low (< -50 dBi). Although
        nothing seems to be happening, the program is calculating and
        plotting the far field but the plot appears as a dot in the
        center of the grid (if the outer ring is a fixed value) or a
        circle at the outside (automatic outer ring scaling). When
        calculation is complete, the maximum gain will be shown to be
        very low (frequently -99.99 dBi).

          Gain is -99.99 or -100 dBi and pattern is circular

        See above problem.

          All the Frequency Sweep traces (pattern plots) are white on a
          color monitor.

        Run EZSETUP and select colors for recalled traces. Frequency
        Sweep uses these same colors for the multiple-trace display.

          Axis system is reversed in View Antenna display

        An axis system which appears to be left-handed or otherwise non-
        standard is due to an optical illusion caused by rotation of the
        display. To return the display to its original position, press
        'R'.




                                       139




          Plot is distorted on screen:

        EZNEC is designed to automatically adjust for the resolution of
        your graphics system type, and it assumes a standard 3:4 aspect
        ratio. EZNEC includes no provision for changing the geometry of
        the plot on screen. Distortion caused by the monitor can only be
        corrected by adjusting or repairing the monitor. Distortion on
        the screen won't cause distortion of the printed plot, however.

          Printed plot is distorted:

        The most likely cause is that the wrong type of printer has been
        specified (e.g., 8/9 pin dot matrix instead of 24 or vice-versa).
        See RUNNING EZSETUP, p. 20. If changing the printer selection
        won't correct the problem, the printer isn't a compatible type;
        see PRINTERS, p. 130.

          Printed plot is negative:

        The printer isn't a compatible type; see PRINTERS, p. 130.

          The program always starts with the "Default" antenna, or it
          shows the "Default" antenna when a different one was recalled:

        The program reverts to the Default when it can't find the LAST.EZ
        file or when a recalled file has been corrupted and EZNEC can't
        read it. The first situation could happen if EZNEC.BAT has been
        moved since it was last run, and can't find the path to the .EZ
        files. If the LAST.EZ file is corrupted, it is no longer usable
        and should be erased.

          Printed plot is garbled:

        You may have specified a laser printer but are using a dot-matrix
        printer, or vice-versa, or you've specified an FX-type printer
        and your printer will recognize only MX graphics. See RUNNING
        EZSETUP, p. 20. Another possibility is that the printer is set to
        emulate an IBM Proprinter. This option, available on many dot-
        matrix printer types, is typically selected with a DIP switch
        setting. If your printer is set to this mode you must use the
        Epson MX driver. If none of these is the case, the printer isn't
        a compatible type; see PRINTERS, p. 130.










                                       140




          Printer "out of paper" error when printer has paper:

        This may happen when using a network printer. The "out of paper"
        indication can be inhibited with the environment variable EZPR1
        (see ENVIRONMENT VARIABLES, p. 136). This also inhibits EZNEC's
        ability to detect an actual out-of-paper condition. However, some
        printers will go off line when out of paper, which will be
        detected and prevent a crash.

          A '%' sign appears in a menu entry:

        This happens if the number of digits required to display the
        entry exceeds the number of spaces allotted for it in the menu.
        It otherwise has no affect on program operation.

          Changes made with EZSETUP don't have any effect:

        EZSETUP modifies the file ELNEC.CFG, which EZNEC reads each time
        it starts. EZNEC always looks in the current subdirectory for
        this file. Likewise, EZSETUP always modifies the ELNEC.CFG file
        in the directory which is current when EZSETUP is running. You
        may be modifying one ELNEC.CFG file and EZNEC is reading another.
        To make sure that EZSETUP is modifying the correct file:

          1. Make sure EZNEC.BAT and EZSETUP.EXE are in the same
        subdirectory. The following step assumes that the subdirectory is
        \EZNEC.
          2. Make sure that the subdirectory containing EZNEC.BAT and
        EZSETUP.EXE is the current subdirectory when running either EZNEC
        or EZSETUP, by typing 'CD \EZNEC' at the DOS prompt before
        running the program.

          Not all the frequency sweep steps show up in MicroSmith when
          the .DAT file is imported

        EZNEC limits the number of frequency steps written in the .DAT
        file because some versions of MicroSmith can handle only a
        limited number. MicroSmith version 2.000B can handle only eight
        steps in imported .DAT files, while later versions can handle
        many more. The maximum number of steps written into the .DAT file
        can be set with EZSETUP (see p. 20). If you have MicroSmith
        version 2.000C or later, you should set the limit to 100 or other
        value specified in your MicroSmith documentation.

          The screen is blank or the plot or grid is invisible:

        A bad choice of colors has been made. You can change colors by
        running EZSETUP (p. 20) or you can erase the file ELNEC.CFG which
        will force use of the default colors.



                                       141




          The program crashes when it's started or when a file is
          recalled:

        EZNEC won't permit you to save a defective file. When a file is
        written, a code number is included and this number is checked
        whenever the file is read. If it's incorrect the file won't be
        accepted and the "Default" antenna is shown instead. It's highly
        unlikely, but possible, that a file could be corrupted without
        changing the code number. If this were to happen to the LAST.EZ
        file, which is read and processed each time the program starts, a
        crash could happen. The cure for this would be to erase the
        LAST.EZ file and any accompanying calculated array files going to
        the subdirectory containing the .EZ files and typing 'del
        last.*'. Likewise, a file which causes crashing when read has
        been corrupted and should be erased. This is an unusual
        circumstance.

        Description files which have been downloaded from another source
        or which were created by other than an EZNEC-family program have
        a higher probability of being defective than ones which have
        locally created by EZNEC. 

          The program crashes under any other circumstances:

        A large amount of effort has gone into making EZNEC "crash-
        proof."  There should be no condition or action on the user's
        part which causes a program crash. (Exceptions: A printer fault
        occurring after printing has begun will cause a crash. It wasn't
        felt that prevention of this occurrence was worth the reduction
        in plot printing speed and increase in code size. Also, entry of
        values outside the range of about +/- 1E-38 to 1E+38, except
        zero, for real numbers; and about +/- 32,000 for integers, can
        cause a crash. This never should be necessary. Unfortunately, one
        source of program crashing hasn't been preventable. IIT
        (Integrated Information Technologies) 80387 coprocessors sold for
        a period of time contain a "bug" which may cause EZNEC to crash.
        Newer chips have the bug fixed. If you have an older machine with
        this brand coprocessor and encounter a crash, please contact me
        for information about obtaining a replacement. If you encounter a
        crash for any other reason, please record the error message. If
        it's possible to duplicate the crash, record the sequence of
        events leading up to it. Another very helpful action is do the
        following: Immediately after the crash, copy the file in the
        EZNEC directory named KEYFILE into a file of a different name.
        Also make copies of the LAST.EZ file and any descriptions which
        were recalled during the session. These will allow the developer
        to re-create the exact sequence of events leading to the crash.
        Send the information to me and I will find and correct the
        problem as quickly as possible and send you a corrected copy
        without charge.


                                       142





                                  ERROR MESSAGES

        EZNEC error messages are intended to be as self-explanatory as
        possible. However, more information sometimes is useful, so some
        messages include an "EZNEC error" number. This section gives more
        information about what causes the error and how to avoid or
        correct it. Following the numbered errors is additional
        explanation of several other possible errors.


          EZNEC error 101

        The TraceView mode requires that a "primary" trace be chosen
        before any other operations can be done. Before a primary trace
        is chosen, EZNEC permits only commands 'RT' (to recall a primary
        trace), 'OP' (to go to the Options Menu so you can choose a
        different directory for traces -- selection 'EZ'), or 'QU' (to
        quit the program). See TRACEVIEW, p. 126.

          EZNEC error 107

        The number of segments in the description exceeds the EZNEC limit
        of 500. The number of segments must be reduced for the file to
        run or be saved. To exit without saving the description, press
        'EX' from the Main Menu.

          EZNEC error 110

        You will see this message whenever a wire extends below ground,
        or has both ends at ground level. Strictly speaking, a wire end
        is considered to be connected to ground if its z coordinate is
        within 0.001 segment length of ground, and below ground if the z
        coordinate is more negative than this.

          EZNEC error 112

        EZNEC was unable to access one of the paths specified in the
        Options Menu. The reported problem will have to be corrected. A
        possible solution to some problems is to change the path in the
        Options Menu. This also applies to EZNEC errors 119, 120, and
        121.

          EZNEC error 113

        During the course of operation, EZCALC writes temporary files
        onto the disk for EZMAIN to read. EZMAIN was unable to retrieve
        the information for the reason shown. The temporary files are
        written in the directory specified by choice 'TP' in the Options
        Menu.


                                       143




          EZNEC error 114

        When EZNEC ends, it saves the current antenna description in file
        LAST.EZ in the .EZ file directory. This error occurs when it is
        unable to do so. If you can't correct the problem shown in the
        error message, you must either change the .EZ file directory
        (selection 'EZ' in the Options Menu) or exit the program by
        typing 'EX'. If you do the latter, the antenna description will
        not be saved.

          EZNEC error 115

        EZNEC was unable to find calculating engine EZCALC.EXE in the
        current directory.

          EZNEC error 116

        An attempt was made to start EZNEC by typing 'EZMAIN'. None of
        the component parts of EZNEC will work alone. EZNEC must be
        started with the furnished batch file EZNEC.BAT, by typing
        'EZNEC'.

          EZNEC error 117

        An error was encountered while writing ELNEC.CFG or a temporary
        copy of it in the current directory. This file contains the
        information specified by the Options Menu and the EZSETUP
        program. All that can be done is to correct the error reported by
        EZNEC. Until the problem is corrected, it may not be possible to
        make changes to ELNEC.CFG.

          EZNEC errors 119, 120, 121

        See EZNEC error 112.

          EZNEC error 125

        EZNEC had trouble reading the file LAST.EZ. This file always is
        written when ending EZNEC with 'QU'. It contains the antenna
        description present when EZNEC ended, and is automatically read
        when EZNEC starts. LAST.EZ resides in the directory specified by
        Options Menu selection "EZ". If you see this error, EZNEC will be
        unable to save or recall antenna descriptions until the .EZ file
        directory is changed to one which can be accessed or the problem
        is corrected.







                                       144




          EZNEC error 126

        One or more transmission lines has both ends shorted, open, or a
        combination of the two. This is not permitted. You can correct
        the problem in the Transmission Lines Menu.

          EZNEC error 127

        Although the calculation portion of EZNEC, which is very memory-
        intensive, uses extended memory, the user-interface portion of
        the program does not. Therefore, if your model has a large number
        of wires and/or segments and an unusually small amount of
        available conventional RAM, EZNEC may not have enough
        conventional memory for View Antenna to function. If you see this
        message, you can make more conventional memory available by
        eliminating resident programs and other users of conventional
        memory, or by loading them into upper memory with a memory
        manager. Or, you can reduce the number of wires and/or segments
        in your antenna model. See MEMORY CONSIDERATIONS AND COMPUTER
        SETUP, p. 24, or pages listed in the index under "Memory,
        conventional".

          EZNEC error 128

        Both ends of a transmission line are connected to the same
        segment. This is not permitted. You can correct the problem in
        the Transmission Lines Menu.

          EZNEC error 130

        EZNEC attempts to predict how much conventional memory will be
        used to save patterns, currents, and other data resulting from a
        calculation. This message appears if this amount of memory isn't
        believed to be available. The calculation is conservative, so it
        might be possible to successfully do the analysis even if the
        message appears. The risk you take is that the program could
        crash without saving any results. The crash is most likely to
        occur after the calculation has completed but before EZNEC
        displays the results. If you decide to attempt the calculation
        anyway, be sure to save your description file before proceeding.
        This error message should be a warning that the conventional
        memory resources are very close to being used up. You should make
        efforts to reduce the complexity of the model (particularly the
        number of wires) or increase the amount of available conventional
        memory. See MEMORY CONSIDERATIONS AND COMPUTER SETUP, p. 24, or
        pages listed in the index under "Memory, conventional" for more
        information.





                                       145




          EZNEC error 133

        One or more wires is too short. NEC regards wires as being
        connected if their ends are within 1/1000 segment length of each
        other. If the length of a wire is less than 1/1000 of the segment
        length of adjoining wires, the adjoining wires will connect to
        each other. The solution is to lengthen the short wire(s). Short
        wires will be highlighted in the Wires Menu.

          EZNEC error 135

        EZNEC requires a VGA or EGA video adapter. It was unable to
        locate a compatible adapter in your computer.

          EZNEC error 137

        Insufficient extended memory is available to start EZNEC. EZNEC
        requires slightly more than 2 Mb to run, even for the simplest
        antenna. Reducing the antenna complexity is unlikely to fix the
        problem; more extended RAM will have to be made available. The
        amount of extended (XMS) memory available can be seen by typing
        'MEM' at the DOS prompt.

        If you see this message when running EZNEC under Windows, see the
        INSTALLATION section beginning on p. 15. The installation
        procedures for Windows systems include steps which increase the
        allotment of memory Windows allows for DOS applications.

          EZNEC error 138

        A discrepancy was found between internal tests for the maximum
        number of segments. If you see this message, please contact the
        EZNEC developer.

          EZNEC error 139

        EZNEC requires disk space to store temporary files. These are
        stored in the directory specified in the Options Menu, and can be
        several megabytes in size for complex descriptions. If the disk
        is being used for virtual memory, the requirement increases. Make
        sure that the temporary file directory specified in the Options
        Menu is the one having the most free space. Otherwise, the only
        solutions are to free additional disk space or reduce the number
        of segments in the antenna description. 








                                       146




          EZNEC errors 140, 141, 142

        Sufficient disk space isn't available to write one or more of the
        Frequency Sweep output files. The message will tell you which
        file there was insufficient space for. Go to the Options Menu to
        see what path was chosen for the file in question. You can either
        change the path to a different disk drive or make room on the
        selected disk by erasing some files.

          EZNEC error 143

        Only extensions .EZ is permitted for description files. If you
        don't specify an extension, .EZ will be added.

          EZNEC errors 147 - 151

        These errors occur when insufficient conventional memory isn't
        available to perform the requested or necessary operation. If
        EZNEC error 149 appears, you must increase the amount of
        conventional memory or replace the file LAST.EZ. LAST.EZ contains
        the last description which was evaluated with EZNEC. EZNEC error
        149 indicates that it's too complex for the currently available
        amount of conventional memory. If you are unable to increase the
        conventional memory, the only solution is to delete or rename
        LAST.EZ, in which case EZNEC will display a default antenna when
        it starts. Alternatively, another description (.EZ) file can be
        copied into LAST.EZ for the program to read as it starts. See
        MEMORY CONSIDERATIONS AND COMPUTER SETUP, p. 24, or pages listed
        in the index under "Memory, conventional" for more information
        about increasing the amount of conventional memory.

          EZNEC errors 201, 202

        Error message text is contained in the file ERRTEXT which should
        be in the EZNEC program directory. If EZNEC can't find or read
        it, it will be unable to display error or information messages.
        EZNEC error 201 results if EZNEC couldn't find the particular
        message in the file, indicating that the file has been modified
        or corrupted. EZNEC error 202 occurs if the file can't be found
        or read. Solving this problem requires re-installing EZNEC, which
        will restore a new copy of ERRTEXT to the EZNEC program
        directory. ERRTEXT is contained in one of the compressed files on
        the EZNEC distribution disk.









                                       147




        Other errors:

          Source(s), load(s), or transmission line(s) on a nonexistent
          wire or open wire end

        This condition prevents EZNEC from correctly performing
        calculations. One circumstance which can cause this error is to
        delete all wires which have sources placed on them. EZNEC will
        leave one source (since one source is required) but place it on a
        nonexistent pulse. Like the above error, it will prevent you from
        running EZNEC, saving the antenna description, or exiting using
        (QU)it. A reliable way to eliminate the error is to place the
        source at the center of wire 1. If you want to exit the program
        without fixing the problem, use (EX)it in the Main Menu.

          "Internal ErrorInternal Error"

        This is symptomatic of a non-functioning or absent coprocessor.
        If you have a separate coprocessor chip, it's possible that it's
        not functioning, despite system information reports to the
        contrary. (Many system analysis programs only check to see if the
        chip is present, not necessarily if it works.) Few applications
        fully exercise the coprocessor, so it's quite possible to have a
        malfunctioning coprocessor without being aware of it. No other
        problem is known to cause this error message.

          "[Error description] occurred in module XXXXXXXX at address
          xxxx:xxxx"

        This is a "crash" of EZMAIN. It's accompanied by program
        termination and return to DOS. Please see the section on crashes
        on p. 142.

          "EZMAIN detects a crash of EZCALC"

        If this message appears with no other information, it may have
        resulted from the presence of left-over temporary files, so try
        starting EZNEC again. If it occurs during normal program
        operation or happens more than once, there are two known causes.
        One is use of a QEMM386 memory manager in its "stealth" mode. The
        other is inclusion of "FRAME = NONE" with the EMM386 memory
        manager. See "Resolving Incompatibilities", p.25, for more
        information about these problems. Another possibility is a
        defective RAM chip or RAM connector contact, which may not show
        up except when a large amount of memory is used for a complex
        antenna. If none of the above seem to be the cause, please record
        all information from the screen (e.g. "Math Error") and contact
        me at the number or address at the end of the manual.




                                       148




          Zero-length wire(s)

        If zero-length wires are present, EZNEC can't place sources or
        loads properly or do other essential calculations. Therefore you
        aren't permitted to leave the Wires Menu while this problem
        exists. When you attempt to leave, however, you're given the
        option of deleting all zero-length wires. Agreeing to the
        deletion will clear the error and permit you to return to the
        Main Menu.


                                      HELP!

        If you encounter a problem with EZNEC, I'll do everything I can
        to resolve it. Before contacting me, however, please first try to
        find the answer to your question here in the manual. If you can't
        find the answer in the manual, write to me at the address below,
        call (503)646-2885 (I'm on Pacific time), fax (503)671-9046, or
        email w7el@teleport.com and I'll be glad to help you -- but
        please consult the manual first!

        It's my sincere intent to make EZNEC as intuitive and easy to use
        as possible while retaining the impressive power of NEC's method-
        of-moments analysis. If you have any suggestions for improvements
        or would care to comment on anything you like or don't like about
        the program, I would very much appreciate hearing from you. I
        would especially like to know if you've observed any
        malfunctioning, unpredictability, or program "crashing". 

        Later versions of EZNEC will be offered to current users at a
        substantial discount.

        Thanks for choosing EZNEC!

                    Roy Lewallen, W7EL
                    P.O. Box 6658
                    Beaverton, OR 97007 U.S.A.















                                       149




                                      INDEX

        .DAT files 117, 128
             maximum number of frequency steps 21, 23, 117, 141
        .EG1 files 129
        .EN (ELNEC description) files 29
             suppressing listing of 136
        .ENT files 126, 129
        .EZ (antenna description) files 102, 128
             extension 124
             path 82, 140
             path, default 82
        .EZG files 129
        .F(#) files 129
        .G(#) (frequency sweep trace) files 129
             path, default 82
        .GAM files 117, 128
             contents 117
        .NGS files 129
        .PF (trace) files 102, 126, 129, 131
             created by other programs, reading 131
             extension 124
             path, default 82
        .PF3 files 102, 105, 126, 129
        $NTEMP files 130
        2D pattern plot display
             entering from 3D pattern plot display 105
        2D pattern plot display and menu 101
        2D plot
             selecting 3D slice 103
        3D Pattern Plot
             learning (Test Drive) 40
        3D pattern plot display and menu 104
        3D plot
             recalling 102, 126
             selecting 76
             selecting slice 106
        3D plot file
             viewing 126
        A/m 61
        Acknowledgements 6
        Adding wires, sources, loads, transmission lines 121
        Aluminum
             alloy, resistivity 76
        ANALYZE 78, 102
             and TraceView 126
        Angle convention 72, 83
        Antenna
             Crossed dipoles 48
             delta loop 88


                                       150




             ground plane 65
             inverted vee 87
             linear loaded 50
             log periodic 50
             multiband 50
             phased array 58, 59
             shunt fed tower 51
             small loop 51
             viewing 81, 93, 106
             Yagi 52
        Antenna description
             combining 78, 123
             deleting 78, 123
             recalling 78, 123
             saving 78, 123
        ANTNOTES.TXT 128
        Automatic segmentation 91
        Axis system
             reversed 139
        Azimuth angle 72, 76
        Balun
             modeling 49
        Beamwidth 78, 102
        Bearing 72, 83
        Beep
             turning off 136
        Browse 78
        Coaxial cable
             modeling 49, 60
        Colors
             2D pattern plot 23
             3D pattern plot display 105
             background 21, 23
             plot 23
             reversing 26, 103, 112
             view antenna display 111
        Combining
             antenna descriptions 78, 123
        Compass bearing 72, 83
        Conductivity
             scaling 68
        Coordinate system 71
             origin 108
        Coprocessor
             IIT brand and crashes 142
             not functioning 148
        Copy protection 6
        Copyright notice 7
        Crash, program 142, 148, 149
        Crossed dipoles 48


                                       151




        Currents
             abrupt changes 46, 65
             and segments 46
             importance of 66
             interpreting 65
             phase of 59
             polarity 65
             symmetry 65
             table 79
             viewing 110
        Cursor
             2D pattern plot, moving 103
             3D pattern plot, moving 104
             SWR graph display, moving 115
        Customer support 149
        Data files
             path, default 82
        Data output files 129
        Date format 21
        dBd 69
        dBi 69
        dBmax 103
        Default antenna 140
        Deleting
             antenna descriptions 78, 123
             traces (far field plots) 102
             wires, sources, loads, and transmission lines 121
        Delta loop antenna 88
        Description
             abbreviated, printing under plot 83
             antenna, printing 81
        Disclaimer 9
        Disk cache 25
        Disk space requirements 13, 24
        Display
             scrolling 73
        E (electric) field 63
        Elevated radials 48, 55
        Elevation angle 73, 76
        ELEVRAD1.EZ 49
        ELEVRAD2.EZ 49
        ELNEC files
             Using with EZNEC 29
        ELNEC.CFG 15, 20, 24, 29, 82, 111, 128, 141, 144
             default values 21
        EMM386 13
             FRAME = NONE 13, 25, 148
        Environment variables 136
        Error messages 143
             "Internal ErrorInternal Error" 148


                                       152




        Errors (see also Problems)
             sources/loads on nonexistent wire 148
             sources/loads on open wire end 148
             wire coordinate 89
             zero-length wires 149
        ERRTEXT 127
        EXit 81
        Extended memory manager 25
        EZCALC crash 148
        EZCALC.EXE 43, 127
        EZDESC.EX_ 127
        EZMAIN.EXE 43, 127
        EZNEC
             ending with QUit 82
             error messages 143
             exit without saving description in LAST 81
             files 127
             starting 31
        EZNEC v. 1
             differences from 28
        EZNEC v. 1 files
             Using with EZNEC v. 2 29
        EZNEC.BAT 43, 127, 140, 141, 144
             environment variables in 137
        EZNEC.TXT 128
        EZNEC.VER 127
        EZPGM.EX_ 127
        EZSETUP 141
             ground file utilities 24
             running 20
        EZSETUP.EXE 128, 141
        Far field
             definition 61
        Feedlines
             modeling 49
        Field strength
             absolute, in V/m or A/m 61
             in mV/m 84
        Field(s) to plot 78
        Files
             .DAT 128
             .EG1 24
             .EN (ELNEC description) 29
             .ENT 126, 129
             .EZ 128
             .EZ path 82
             .EZG 24
             .F(#) 129
             .G(#) (frequency sweep trace) 129
             .GAM 128


                                       153




             .PF (trace) 126, 129
             .PF3 102, 105, 126, 129
             $NTEMP 130
             ANTNOTES.TXT 128
             created by EZNEC, EZSETUP 128
             data output 129
             ELNEC.CFG 15, 20, 24, 29, 82, 111, 128, 141, 144
             ELNEC, using with EZNEC 29
             ERRTEXT 127
             EZCALC.EXE 127
             EZDESC.EX_ 127
             EZMAIN.EXE 127
             EZNEC 127
             EZNEC v. 1, using with EZNEC v. 2 29
             EZNEC.BAT 43, 127, 140, 141, 144
             EZNEC.TXT 128
             EZNEC.VER 127
             EZPGM.EX_ 127
             EZSETUP.EXE 128, 141
             frequency list file 118, 135
             ground data 24, 29, 83, 129
             ground data, tolerance 84
             import wires, rules 133
             INSTALL.EXE 127
             INTERACT.INI 128
             KEYFILE 142
             LAST.EZ 128
             LASTZ 116, 118, 129
             LF90.EER 128
             MicroSmith 117
             NFTEXT 128
             on the distribution disk 127
             OPENPF.TXT 128
             saving, recalling, deleting 123
             temporary 130
             temporary, path 82
        Fix segments 81
        Frequency 74
        Frequency list file 118, 135
        Frequency scaling 67, 74
        Frequency sweep 80, 116
             data output file 117, 119
             frequency list file 118, 135
             menu 116, 118
             MicroSmith files 119
             pattern plots (traces) 119
             plots, interim 84
        Frequency Sweep Menu 116
        Front/back ratio 78, 102
        Front/side ratio 78, 102


                                       154




        Front/sidelobe ratio 78
        Gain 102
             -99.99 dB 139
             antenna over ground 66, 69
             forward 78
             reference 69, 77
        General information and conventions 71
        Getting started 14
        Graphics adapter 140
        Grid style 83
        Ground
             conductivity 100
             conductivity and dielectric constant 54
             conductivity and dielectric constant, table 100
             conductivity, default 84, 100
             connecting loads to 96
             connecting sources to 95
             connecting wires to 55, 86, 88
             constants, default 84
             data files 29, 83
             data files, tolerance 84
             dielectric constant 100
             dielectric constant, default 84, 100
             height 101
             modeling 54
             NEC buried radial model 124
             NEC buried radial model, enabling 125, 136
             NEC buried radial model, specifying 125
             real, Fast Analysis 54
             real, High-Accuracy 54, 83
             real, limitations of model 55
             real, MININEC-type 54
             real, model types 54
             reflection-coefficient 54
             Sommerfeld 54
             specifying 99
             type, selecting 75
             types of 54
             wire at or below 89, 143
        Ground description, real 75
        Ground files 24, 29, 83, 129
        Ground plane antenna 65
        Group edit 90, 120
             starting 121
        Guideline check 47, 81, 84
        Guy wire 53
        H (magnetic) field 63
        Hardware key
             installation 16
        Hardware requirements 13


                                       155




        Hazard
             using EZNEC to determine 9
        Height, antenna
             changing 90
        Help
             how to get 149
        Highlight slice 105
        Highlight wire 110
        HPIB 130
        IIT brand coprocessor
             cause of crash 142
        Impedance
             feedpoint 64, 79
             source 64, 79
             user-defined, for SWR 77
        Importing wires 90, 132
             file description 133
        Incompatibilities 13
        INSTALL.EXE 127
        Installation 15
        INTERACT.INI 128
        Internal Error message 148
        Interpreting results 63
        Inverted vee antenna 35, 87
        Isotropic radiator 69
        Key
             hardware, installation 16
        KEYFILE 142
        Laplace transform
             automatic RLC entry 96
             using 96
        LAST.EZ 81, 82, 128, 147
             and TraceView 127
             defective 142
             not found 140
        LASTZ 116, 118, 129
        Letters, lowercase and uppercase 71
        LF90.EER 128
        License agreement 7
        Limitations
             maximum number of sources, loads, transmission lines,
             segments 73
        Linear loaded antenna 50
        Load data 66
        Loading coils 56, 66
        Loads 75
             adding 96
             connecting to ground 96
             connection to sources and transmission lines 57, 60, 96
             deleting 96


                                       156




             impedance, specifying or changing 96
             Laplace transform 96
             loss 66, 79
             maximum number of 73
             on nonexistent wire 148
             on open wire end 148
             placing at wire junction 56, 79
             position of, specifying 96
             split 56, 79
             using 56
        Loads Menu 96
        Log periodic antenna 50
        Loop
             delta 88
             quad 50
        Loop antennas
             small 51
        Loss
             ground connection 46
             ground system 54, 124
             load 66
             loading coil 56
             power 85
             source and load 95
             transmission line 59, 98
             trap 56
             wire 64, 68, 75
        LPT1: 20
        Main Menu 74
        Media 55
             adding 101
             boundary 55, 100
             boundary, changing type 101
             deleting 101
             height 55, 101
        Media Menu 99
        Memory
             available, displaying 78
             conventional (lower 640k) 18, 24, 25, 78, 145
             conventional (lower 640k), insufficient 24, 145, 147
             extended (XMS) 13, 17, 20, 24, 31, 74, 78, 136, 145, 146
        Memory manager 25
             setup 25
        Memory requirements 13, 24
        Menus 74
             2D Plot Menu 101, 104
             3D Plot Menu 104
             Frequency Sweep Menu 116
             Loads Menu 96
             Main Menu 74


                                       157




             Media Menu 99
             Near Field Setup Menu 115
             Options Menu 82
             Sources Menu 94
             SWR Graph Menu 114
             Transmission Lines Menu 97
             View Antenna Menu 106
             Wires Menu 85
        MicroSmith 117, 130
             files 21, 23, 117, 119, 128
             maximum number of frequency steps 21, 23, 117, 141
             ordering information 130
        MicroSmith files
             path, default 83
        Modeling 44
             antenna structure 45
             complex structures 68
             introduction to 45
        Modifying wires, sources, loads, and transmission lines 121, 122
        Monitor
             color 23
             LCD 21, 23
             monochrome 21, 23
        Moving wires, sources, loads, and transmission lines 121
        Multiband antennas 50
        Near field
             definition 61
        Near field / far field analysis 61
        Near field analysis 79, 115
             interpreting results 63
             setup 80
        Near Field Setup Menu 115
        NEC
             differences from 12
        NFTEXT 128
        NoFlash 113, 136
        Notebook computers 109
        OpenPF plot file standard 131
        OPENPF.TXT 128
        Options Menu 82
        Origin
             coordinate system 108
        Out of environment space message 137
        Output files
             path, default 82
        Patterns (see also Traces) 63
             frequency sweep 117
        Permeability
             wire, specifying 75
        Phase, current 110


                                       158




        Phased array antennas 59
             feed systems 58
        Plot
             3D, recalling 105
             3D, saving 105
             distorted, printed plot 140
             garbled, printed plot 140
             generating 80
             outer ring value 77
             printing 102
             style 83, 103
        Plot type 76
        Plot/table range 76
        Plots
             inserting in Windows documents 26
             reversing color of 26
        Plotters 13, 22, 136
        Polarization 78
        Power
             loss in loads 66
        Power level
             specifying 57, 85, 95
        Preserve connections 93
        Print Description 81
        Print quality
             24-pin printer 84
        Printer port 13, 20, 22
        Printers 20, 130
             color 22
             dot matrix 21, 130
             Epson FX 21
             Epson MX 22
             false "out of paper" 141
             HP DeskJet 22
             HP DeskJet 500C 22
             HP DeskJet color 22
             HP LaserJet 22, 130
             HP or Epson emulation 22
             HPIB 130
             IBM 21, 130, 140
             initialization and end strings 22
             laser 22, 130
             serial bus 130
             types 21
        Problems (see also Errors) 138
             -99.99 dBi gain 139
             % sign in menu entry 141
             blank screen 141
             default antenna 140
             distorted plot 140


                                       159




             distorted printed plot 140
             EZNEC disagrees with another program 138
             EZSETUP has no effect 141
             false printer "out of paper" 141
             frequency sweep traces all white 139
             garbled printed plot 140
             grid but no plot 139
             hardware key 16
             MicroSmith .DAT file frequency steps 141
             monitor flashes 139
             negative printed plot 140
             negative source resistance 138
             out of environment space 137
             program crashes 142
             reversed axis system 139
        Processor type requirements 13
        Progress "thermometers" 31
        QEMM386 13, 73
             "stealth" mode 13, 25, 148
        Quad loop 50
        QUit 82
        Race course (Test Drive) 40
        Radials
             creating 91
             elevated 48, 55
             ground, length and diameter 68
             ground-plane antenna 65, 87
             NEC buried radial model 124
             NEC buried radial model limitations 125
             NEC buried radial model, enabling 125, 136
             NEC buried radial model, specifying 125
        RAM requirements 13, 24
        Real ground description 75
        Recall Trace 126
        Recalling
             antenna descriptions 78, 123
             traces (far field plots) 102
        Reference manual 70
        Resistance
             low 64
             source, negative 64
        Resistivity
             wire, scaling 68
             wire, specifying 75
        Results
             interpreting 63
        Reversing colors 103
        RLC, series or parallel, entering 96
        Running EZNEC 30
        Safety


                                       160




             using EZNEC to determine 9
        Saving
             antenna descriptions 78, 123
             traces (far field plots) 102
        Scaling
             frequency 67, 74
        Scientific notation 71
        Scrolling 73, 123
        Segmentation
             automatic 46, 81, 91
        Segments 46, 107
             and accuracy 46
             and computation time 46
             doubling the number of 66
             length limits 50
             length of 110
             maximum number of 73
             number of, choosing 50, 53, 65
             number of, entering 88
             tapering length of 67, 91
        Shunt fed towers 51
        Sidelobe 78, 102
        Significant digits, number of 71
        Skin effect 75
        Slice
             highlighting in 3D display 105
             selecting 103, 106, 114
        Small loop antennas 51
        SMARTDRV 25
        Source
             selecting, SWR graph display 115
        Source data 79
        Sources 75
             absolute 57, 85
             adding 95
             amplitude and phase 95
             at junction of two wires 59
             connecting to ground 95
             connection to transmission lines 57, 60
             current 58, 95
             deleting 95
             maximum number of 73
             multiple 59
             negative resistance 138
             on nonexistent wire 148
             on open wire end 148
             on short wires 48, 57
             polarity 59
             position of, specifying 94
             power 57


                                       161




             relative 57, 85
             split 57, 95
             types 57
             using 57
             voltage 58, 95
        Sources Menu 94
        Starting EZNEC 31
        Step size 77
        Stepped diameter wires 51
        Stepped-diameter correction 31, 50, 51, 85
             showing 90
        SWR 64, 77, 79
        SWR graph 80
             learning (Test Drive) 42
        SWR graph display
             changing frequency range 115
        SWR graph display and menu 114
        Table
             plot data 80
             units 84
        Tapering 51
             diameter 51
             segment length 51, 53, 57, 91
        Templates 68
        Temporary files 130
        Test drive 31
        Thermometers
             calculation progress 31, 71
        Three dimensional plot
             selecting 76
        Tips 66
        Title 74
        Towers
             shunt fed 51
        Traces (far field patterns) (see also Patterns)
             clearing 102
             deleting 102
             frequency sweep 117
             recalling 102
             saving 102
             viewing with antenna 107, 112
        TraceView mode 31, 126
        Transmission lines 75
             connection to sources 60
             connection to sources and loads 57, 60
             connection to wires 60
             maximum number of 73
             reverse/normal connection 99
             specifying end positions 98
             specifying length 98


                                       162




             specifying velocity factor 99
             specifying Z0 98
             using 59
        Transmission Lines Menu 97
        Traps 56, 66
        Units 76
             changing 93
        Upgrading 29
        Upgrading from EZNEC v. 1 27
        V/m 61, 84
        Velocity factor
             transmission line 99
        View Antenna 72, 81, 93, 106
             highlight wire feature 110
             operation 108
             reversing color of 26
             selecting trace slice 114
             viewing current phase 65
             viewing currents 65
        View Antenna Menu 106
        Virtual RAM 82
             calculation progress 31, 71
             using the hard disk as 24, 31
        Warranty 8
        What's happening 43
        Wild card 102, 123
        Windows
             allotting memory for EZNEC 26
             EZNEC PIF 16
             inserting graphics in documents 26
             inserting plots in documents 26
             running EZNEC under 13, 25, 26
             windows 95 16
             windows NT 19
        Windows 3.xx
             installing program for use with 16
        Windows 95
             installing program for use with 16
        Windows NT
             installing program for use with 19
        Wire gauge 75
             radials 125
             wire diameter, specifying as 88
             wire diameter, specifying as, example 33
        Wire grid 47
        Wire loss 64, 75
        Wires 45, 75
             adding 89
             at or below ground level 89, 143
             closely spaced 47, 48


                                       163




             connected 107
             connecting to ground 55, 86, 88
             connecting to other wires 46, 47, 85, 86, 88
             connecting to real ground 54, 55, 136
             coordinates, changing 122
             crossed 139
             deleting 89
             diameter, entering or changing 88
             diameter, limits 45
             diameter, specifying as wire gauge 88
             diameter, specifying as wire gauge, example 33
             direction 59
             end coordinates 45
             end coordinates, entering 86
             end coordinates, errors 89
             end coordinates, specifying 59
             guy 53
             importing 90, 132
             joining at an acute angle 53, 67
             length, changing 87
             maximum number of 73
             modeling 47
             permeability 75
             preserving connections 93
             radial, creating 91
             resistivity 75
             rotating 87
             rotating, example 37
             showing unconnected ends 112
             stepped diameter 51
             unconnected 107
             zero-length 149
        Wires Menu 85
        Yagi antenna 52
        Z0 (characteristic impedance)
             changing, SWR graph display 115
             specifying alternate for SWR 77
             transmission line 98
        Zero-length wires 149
        Zoom
             view antenna 109











                                       164
