"Owen Duffy" wrote in message
...
"Wayne" wrote in
news:srSpi.4065$9A6.827@trnddc01:


"Owen Duffy" wrote in message
...
"Wayne" wrote in
news:cbKpi.3766$7w.1151@trnddc05:

...
You might try the matching system used on the old "Gotham
Vertical". This uses a tapped coil from the base of the mast to
ground. The top of the coil is tapped down until resonance is
found. Coax braid is to ground, and the coax center conductor is
tapped up from the bottom of the coil for best match.

Whilst this system might work for an antenna with a capacitive
feedpoint, will it work for an inductive feedpoint such as this ~3/8
lambda attena?

Owen

Just add enough coil to bring it to 3/4 lambda resonance. Wouldn't
that work?

I don't really understand exactly what you mean, though I know it is a
popular proposition.

If the antenna feedpoint is around 100+j300 (see my previous posting),
the simplest matching network is an L network, and there are two
solutions to it, but both L networks in this specific case require an L
and a C, and both use practical values of L and C. For example, a 84pf
capacitor in shunt with the feedpoint, then a 2.4uH inductor in series
from the feedline to the feedpoint will deliver that transformation with
reasonable efficiency and with one side of the capacitor grounded.

Can you propose the values of a two inductor L network, or a tapped
inductor that will transform 100+j300 to 50+j0.

Owen
I spent some time pondering this with EZNEC and a smith chart. No, I can't
come up with an inductive way to match it. I learned somthing
today...thanks!