[TowerTalk] 43ft Vertical Feeding Question and Balun type,

[Rob Atkinson]

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