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[TowerTalk] Ant Modeling

To: <towertalk@contesting.com>
Subject: [TowerTalk] Ant Modeling
From: n4zr@contesting.com (Pete Smith)
Date: Fri, 18 Jan 2002 14:39:21 -0500
At the suggestion of Tom, N4KG, I am reposting this to the reflector as well.

At 08:19 AM 1/18/02 -0600, you [Tom] wrote:
>Hi Pete,
>
>Is EZNEC windows or DOS based?
>How well does it model very low antennas such as Beverages?
>or elevated GP's with radials at 10 ft on 80M?
>
>Would EZNEC be worth buying if I already have ELNEC?

The latest EZNEC is Windows based.  I believe that W8JI uses it for
modeling Beverages and other receiving arrays.  According to the manual, no
special techniques are required if the conductor is at a height of at least
.001 wavelength (under a foot on 160).

It would definitely be worth trading up, because ELNEC is based on MININEC,
which is really only usable at heights above 0.2 wavelengths (feedpoint
impedances are wrong below that height, and there may be other issues with
traveling-wave antennas -- this I don't know).  EZNEC uses the NEC-2
engine, which is the best thing you can reasonably get, unless you can
obtain NEC-4 without paying the exorbitant license fee.

If I were doing it over again, I would at least consider NEC-Win Plus.  It
also uses NEC-2, allows a much larger number of segments and is much more
amenable to handling geometrically difficult problems like modeling a yagi
stack with the antennas at dissimilar azimuths other than 90 or 180 degrees
from each other.  It costs $150 vs $89.95 for EZNEC.  You may also get a
better price for EZNEC by virtue of being an ELNEC user, if you are
registered with Roy.

[I should add here that the available number of segments matters when you
are trying to model interactions in your entire antenna installation -- it
is easy to run out, particularly at the higher frequencies.]

I'd also suggest you take a look at http://www.cebik.com/radio.html.  W4RNL
has compiled an excellent compendium of information on modeling programs
and their capabilities/limitations.

 



73, Pete N4ZR

Sometimes a tower is
just a tower





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