Re: NEC-LIST: Software to model effect of boom on elements for UHF yagis?

I can't help directly, but the preferred construction places the element
*through* and *insulated from* the boom. I believe this reduces
(but not eliminates) the boom thickness influence. For example, with a
square tube (hollow) boom two thru-insulators would be used, one on
each side wall of the boom. Look at 23 cm products from M-squared:

http://www.m2inc.com/

As a guess, you will likely have more trouble with raindrops on the element
tips, presuming an outdoor S-band yagi.

dan bathker

 At 01:55 PM 3/21/2002 -0500, Ed Troy wrote:
>Does anyone know of any software that will accurately model the effect of the boom on the length of the elements of a UHF yagi? Obviously, something free or inexpensive is preferred, but I am wondering if anything models this effect.
>
>Of course, for most yagi antennas, the effect is almost insignificant, since the boom diameter is such a small fraction of the element lengths, even if they pass through, and are physically connected to, the elements. But, if you are designing a long yagi array at 2.5 GHz, using, say, a 1/4 inch diameter boom, and 1/8 inch diameter elements, the boom diameter is more than 10% of the total length of the elements, and thus a NEC simulation is grossly inaccurate.
>
>I have found rough guidelines and some programs that supposedly allow you to correct element lengths for the effect of the boom diameter, or that even design a yagi given the boom diameter and element diameters. But, I would like something that would allow me to accurately predict the performance before going through the time and expense of actually fabricating the antenna.
>
>TIA,
>Ed
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Dan Bathker

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