I assume you're using the YFW program from the book?
As I recall, the element lengths are really the "half lengths", (actually,
it's the lengths of each segment of tubing, moving out from the center) but
it doesn't do optimization, just allows you to change things and see what
the estimated pattern and feedpoint impedance is.
There are a couple free/inexpensive modeling tools available that can do
optimizing. MultiNEC and 4nec2 are both available off the web, and both do
optimizing, using the NEC2 engine underneath (or NEC4, if you've got it).
Be aware, though, that there are some subtleties to correctly modeling
tapered elements properly with NEC based programs. 4nec2 does do automatic
segmentation and tapering, and warns you if your model violates some of the
"rules of thumb".
In YfW, a different technique is used for the modeling; essentially it's
restricted to parallel wire/tube elements in a single plane, so it's
computationally less intensive (i.e. you could use a slide rule to do the
calculations). I assume YfW has the appropriate stuff to handle stepped
diameters, although I've not checked.
> [mailto:towertalk-bounces@contesting.com] On Behalf Of EL34GUY@aol.com
> Sent: Monday, March 21, 2005 8:47 PM
> To: towertalk@contesting.com
> Subject: [TowerTalk] Yagi for Windows pgm
>
> Hello Everyone,
>
> Ive been trying to adapt a Wilson 40ft boom 5 element 20 meter monoband
> antenna into a 20 meter optimized wideband yagi that's got a 48ft boom and
> six elements. Needless to say I havent had very good results in doing so.
I
> have built the file with the Wilson 5 element beam but the tool doesn't
seem
> to handle the changes Im making very well. Anyone use this tool
effectively?
> Its the one that's in the ARRL antenna book. Any suggestions? Also, I
need
> some 7 or
> 8 conductor 14 or 16 gauge stranded wire for my hallicrafters rotor. Any
> idea where to find it? Thanks very much and 73
>
> Mark
> W0NCL
_______________________________________________
See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless Weather
Stations", and lot's more. Call Toll Free, 1-800-333-9041 with any questions
and ask for Sherman, W2FLA.
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