Rob,
A 43 foot vertical is 5/8 wavelength on 20 meters. With appropriate radial and
matching systems it can be an excellent antenna on 80 through 20 meters, and a
fairly good antenna on 160 and 17 meters.
73
Frank
W3LPL
---- Original message ----
>Date: Thu, 20 Nov 2008 11:49:33 -0600
>From: "Rob Atkinson" <ranchorobbo@gmail.com>
>Subject: Re: [TowerTalk] 43ft Vertical Feeding Question and Balun type,
>To: towertalk@contesting.com
>
>I've wondered before what the deal is with 43 foot verticals. By
>that I mean, it seems suddenly I started seeing 43 feet mentioned all
>over the place for an "all band vertical." Is 43 feet some magic
>length? How was this determined and who originated this idea? I
>figured maybe it was something that had been in the handbooks for
>years and I never knew about it.
>
>Anyway, having a bizarre feedpoint Z isn't necessarily a bad thing by
>itself. It just means you need a matching network at the feedpoint to
>tune the antenna to 50 ohm unbalanced feed. What's bad is having a
>vertical so tall in wavelength that you wind up with all or most of
>your RF going off in one or more high angle lobes. That starts to
>happen when length begins to get beyond around 200 degrees or 5/8
>wave. There are all these little high angle lobes that gradually
>multiply and get bigger as you go up in frequency. You have to figure
>out how high you can go in frequency with 43 feet before that happens.
>
>Don't be persuaded by big signal reports on some 100 w. operation with
>no radials. The right band for the distance with good conditions
>and enough power can do wonders. 20 over S9 with 100 watts when
>everyone else on the band is running 1.5 kw and is less than S9...now
>that's an antenna!
>
>73,
>
>rob / k5uj
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