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Tower switching service as antenna

linearone

King of NY
Apr 2, 2005
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Rotten Apple Trees
www.acboxes.com
Probably over a decade ago I remember looking at a website and this gentleman did something very clever. He had a couple of stacked Yagis on top of a tower, each one covered a different band.. but he did something with a box with a bunch of relays in it where I think what he did was disconnect the Earth ground from the tower and somehow the tower could get switched in line with one of the other antennas to become an antenna itself or part of another antenna. It wasn't acting as a counterpoise when the switches were thrown it became an actual transmitting antenna. Does anybody know what I'm talking about? I mean I would assume you would need some sort of gamma match something that would allow the tower to remain a DC ground and then some relays to switch it in and out, it was for a very low band. I wish I could find the website I've been googling it for 2 days and I can't come up with anything.
 
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It's commonly done with AM radio towers. The tower itself sits on an insulator and is used to radiate the AM radio station (which is a low frequency). The tower can also be used at the same time to support cellular, FM broadcast, or land mobile antennas for various services. These and the tower lighting are fed through various kinds of chokes and transformers in order to keep the tower, which itself is radiating, isolated from ground.
 

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Thank you thank you thank you
 

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