[TowerTalk] An antenna question...

[Robert Chudek]

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 - KØRC in MN