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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