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[TowerTalk] Antenna Modeling Programs

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Subject: [TowerTalk] Antenna Modeling Programs
From: (L. B. Cebik)
Date: Thu, 13 Mar 1997 08:11:39 -0500 (EST)
I have added a page to my site with links to some of the main web pages of
antenna modeling software providers.  I thought the basic info might
interest members of the list, so I added the links visibly to the text
below.  I hope the info is useful to some.
Antenna Modeling

Some Notes on Antenna Modeling Programs

Much of my antenna research work is based on systematic antenna modeling in
a version of the Numerical Electro-magnetics Code (NEC).  The following
brief notes will provide links to antenna modeling software providers.


The latest version of NEC is NEC-4, which overcomes most of the
shortcomings with earlier codes.  It permits the modeling of underground
radial systems, elements of varying diameter sections, carefully-
constructed close-spaced parallel wires, as well as all the modeling
capabilities of earlier versions of the code.  NEC-4 is a proprietary code
of the University of California, from whom a user-license must be obtained. 
Export restrictions apply.


At present, I know of only one source of commercial software for NEC-4: 
Roy Lewallen, W7EL.  EZNEC Pro has an option for NEC-4, if the purchaser
has a confirmed license for NEC-4.  EZNEC Pro is also available for NEC-2
(see below).  W7EL also makes available EZNEC, a segment-restricted version
of NEC-2, and ELNEC, a version of MININEC 3.  All W7EL software packages
are for DOS and employ similar user interfaces which have earned praise in
many circles.


NEC-2 is a highly capable version of the code which is in the public
domain.  It is restricted to antenna elements of a single diameter
(although some software providers have introduced corrections for linear
elements whose diameters varies).  It cannot handle buried radial systems,
although above ground systems close to the earth can be handled.  However,
it is equipped with the Sommerfeld-Norton high accuracy ground model for
accurate modeling of horizontal wires close to the earth.


Nittany Scientific produces a Windows version of NEC-2 at two levels: 
NECWin Pro (NWP) and NECWin Basic (NWB).  Both employ a spreadsheet
geometry construction page, pull-down boxes for other antenna parameters,
and Windows-style graphical outputs.  In addition, NWP provides direct
entry or importation of NEC model input "cards" and provides a large
assortment of available rectangular output graphics, along with other
advanced NEC capabilities.

MININEC "Professional"

Before recent advances in speed and memory, it was not feasible to run NEC
on a PC.  Rockway and Logan developed MININEC, a Basic language adaptation
of NEC for PCs.  More recently, they have advanced the MININEC algorithms
and code to overcome many of its initial limitations.  The "new" MININEC
can handle sharp angles in antenna geometry directly (without segment
length tapering) and handles antennas close to ground with much better
accuracy.  However, the MININEC Professional code is a proprietary product.


EM Scientific offers several levels of MININEC Professional, ranging from
the basic level MININEC for Windows to MININEC Broadcast Professional. 
These are all Windows products.


The public domain MININEC code (version 3.13) is available with several
commercial user interfaces, as indicated in these notes.  For general
antenna analysis that does not press its limitations, MININEC is a highly
competent code.  It handles elements of changing diameter directly, and
with segment-length tapering, can accurately model a wide range of antenna
geometries.  However, horizontal antennas must be at least 0.2 wavelengths
above ground for accurate results.  Moreover, specification of ground
conditions affects only antenna far field results, but not feedpoint


Orion of Canada offers a Windows-based version of MININEC, using a
spreadsheet geometry input page, pull down boxes for other antenna
parameters, and a pattern plotting output that includes lobe identification
and bandwidth.  In addition, the user can vary the height of the antenna
without invoking a complete recalculation of the matrix for faster results.

Other NEC and Antenna Software


ASL Antenna Software Ltd of Great Britain offers a range of specialized
antenna software.

The sources listed above have web pages for further information on the
relevant software.  Brian Beezley, K6STI, also offers a wide range of NEC-
related software, as well as a Yagi optimization program, a terrain
analysis program, and DSP software.



The Applied Computational Electromagnetics Society (ACES) is perhaps the
professional focal point of advances in all forms of electromagnetics codes
and related mathematical models.  It holds an annual meeting on the west
coast in March with a very full and varied program.

This listing is necessarily limited.  However, the indicated web pages will
lead you to other information on details, specifications, related
developments, and a more complete understanding of the rapidly expanding
field of electromagnetic modeling.



L. B. Cebik, W4RNL         /\  /\     *   /  /    /    (Off)(423) 974-7215
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