[TowerTalk] Reverse Fed Towers

[Jim Lux]

On 12/15/15 9:45 AM, wosborne44 at 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.