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Re: [TowerTalk] Reverse Fed Towers

To: towertalk@contesting.com
Subject: Re: [TowerTalk] Reverse Fed Towers
From: Jim Lux <jimlux@earthlink.net>
Date: Tue, 15 Dec 2015 11:47:00 -0800
List-post: <towertalk@contesting.com">mailto:towertalk@contesting.com>
On 12/15/15 9:45 AM, wosborne44@gmail.com wrote:
I have a tower that has a base that is in concrete and grounded.  I
would like to make it a vertical without installing insulators.   Has
anyone used elevated radials with reverse feeding, i.e., connecting the
center conductor to the radials and the shield to the grounded tower?  I
see this in the ARRL handbook but I cannot seem to make a model of it
work.  Any help would be welcome.

What about shunt feeding?

there's nothing special about the vertical being insulated from the ground plane. It's all about getting a current to flow, and it's "convenient" if you can connect center conductor to vertical and shield to ground plane in a gap between the two. But there's no requirement for it, any more than you need to have a gap in a dipole.

If you look at a gamma match for a Yagi, that's what it's doing.

Basically in all these sorts of schemes, you cause current to flow in a wire that is parallel to the radiator, and the magnetic fields couple, causing current to flow in the radiator as well.

There are interesting stories about using a tree as a vertical using techniques like this.. including one with a big magnetic core around the tree and the feedpoint driving a coil around the core.

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