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[TowerTalk] HELP!!!!

To: <>
Subject: [TowerTalk] HELP!!!!
From: (Jim Lux)
Date: Sat May 17 19:28:33 2003
I haven't actually seen one of these antennas, but I have looked at their
website, and have seen similar antennas..

From: <>
> In a message dated 5/17/03 1:05:05 PM Pacific Daylight Time,
> writes:
> > Thinking about buying the small Sommer antenna.
> >
> >  Comments please.
>     Two personal comments.
>     1) It's a VERY complicated structure with MANY parts. I don't
> specifically of any mechanical problems though. Figure a bunch of
> construction time.

Indeed it is complicated. Antennas with lots of conductors closely spaced
tend to, as a class, have very picky design tolerances. Sort fo the opposite
of a single frequency dipole (about as simple as you can get), where not
having it perfectly horizontal or having the legs uneven or having the
length a bit wrong doesn't change it's efficiency (it might change the
feedpoint Z, but the loss and effective aperture isn't going to change

For this antenna, a lot of its claimed performance hangs on mutual
interactions between the elements to form matching networks and to get the
current distributions right.  Small changes in dimensions (as from wind,
ice, age, dropping, misassembly) might have huge effects on the loss and
tuning performance. "Might" is the operative word here... you'd need to talk
to someone who has used one for some significant time, AND, who has also
used something else, so they have a basis for comparison.

>     2) If this was a good performing antenna, there would be lots of
> contesters using them. They don't.

Contest folk might choose antennas for many reasons other than RF
performance: durability, good performance in a stack, cost.  Performance is
a trade space with many many variables.  A wire strung over a tree and a
tuner might be a good performing antenna for a backpacker, where every gram
counts.  Just because a successful contestor uses type X antenna doesn't
necessarily mean that type X antenna is good for someone else.  So much of
contesting is personal skill and familiarity with your gear, over a long
time, is probably part of it. Otherwise you could just go "buy the contest",
and I'll bet more than one person has tried that and failed.  The backpacker
with the wire and good skills might do better than the rookie with the full
on Wullenweber array with adaptive steering, or a multibay steerable curtain
array shortwave broadcasting antenna (Running 1500 W into 20 dBi of gain
would tend to make you the "loud signal on the band", but if you can't log
the contacts or get tongue-tied, you're just loud, not good)

Jim, W6RMK

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