On Jun 24, 6:16*pm, Richard Clark wrote:
On Tue, 24 Jun 2008 17:41:31 -0700 (PDT), Nick

wrote:
I also don't want to add
what may be a useless choke at the antenna's feedpoint, since that
would decrease the antenna system's efficiency due to the choke's
resistive losses...

Hi Nick,

A choke at the feedpoint does NOT add loss.

The Choke (which may be resistive insofar as the bulk material's
property) is in the Common Mode circuit. *The load is in the
Differential Mode circuit. *You want a very, very high Z (or R, it
makes no difference) in the Common Mode circuit. *The choke is
entirely transparent to the Differential Mode circuit.

If you don't understand the difference between the two modes (and it
is not a common topic outside of electronics design) then, no doubt,
others will fill in (or simply go to wikipedia).

73's
Richard Clark, KB7QHC

Thanks for the further info Richard! I guess I don't really fully
understand why the pure resistive losses in the coax choke wouldn't
affect the efficiency of the monopole. If I understand you correctly
(and I may not!), then even if we increase the impedance of the coax
choke to insane levels, such as by making it 1000 feet long and
winding it on a six inch diameter PVC form, then the huge losses
normally inherent in such a long run of coax would not be seen at all
by the vertical because it is wound on the PVC form? (I'm not arguing
with you at all, I just really want to know).

73,

-Nick