Bob:
Just to add fuel to the fire: W1BB, the Old Man of Topband, used a silo in
Massachusetts, right on the coast, as a support for a wire beam on 160M. He
hung two inverted-Vee wire dipoles of appropriate lengths off the silos and fed
one of them, using the other as a reflector element.
73 de
Gene Smar AD3F
From: Robert Chudek <k0rc@pclink.com>
Date: 2007/11/06 Tue PM 05:10:48 CST
To: TowerTalk@contesting.com
Subject: [TowerTalk] An antenna question...
I operated CW Sweepstakes from North Dakota last weekend. There was plenty of
time (10 hours) to look at the flat, fertile, harvested landscape. I discovered
the North Dakota pioneers DID have a sense of humor because one of the towns
along the way was named "Hillsboro". I got a chuckle out of that...
In addition to seeing the horizon, there were plenty of grain elevators and
huge silos dotting the landscape. The "ham" side of my brain (that's the side
that's fully cooked) started thinking these concrete silos would make a great
support for a 160m vertical dipole. Down the road a bit I saw a METAL silo and
the thought entered my mind "Hey, that might make a great, wideband, 160m
vertical if fed properly". The majority of these buildings would be at least a
1/4 wavelength in height. My question is whether anyone has experimented with
these ideas?
The second question I have is along a similar line... (BTW, these silos are
probably 100 feet in diameter or larger in some cases making them really "fat"
radiators.) How effective would a metal silo be as a reflecting surface for a
sloping dipole? And if you had a 160m sloping dipole on one side and a 80m
sloping dipole on the opposite side, would there be any RF isolation using the
silo as a common reflector? My initial thought was, yeah probably, there's
physical separation and there's a couple layers of metal between the radiators.
Then my thought turned to RF traveling via the skin effect, so a 160m signal
might propagate all the way around the silo to the other side. Any thoughts or
experiments about this?
73 de Bob - KÃÂRC in MN
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