On Mon, 08 May 2006 02:55:04 GMT,
wrote:
[snip]

If it's what I think it is the design is a coaxial feed section with
a 1/2wl radiator. The difference being a coax fed rather than a
balanced line feed. In either case it relies on an unterminated 1/4wl
section reflecting a high impedence to match the end impedence of
a 1/2wl section. That being something in the range of 3000-5000
ohms (at resonance).

There is also a third way to implement. use a lumped tuned circuit
and tap the coax up from the bottom for match. The tuned circuit is
parallel resonant with the 1/2wl section attached to the top. I've
built this for use with my VHF HT and is about 38" for the radiator
and the coil at the bottom looks like a baseloading coil. Works
way better than a rubber duck but at 40" long overall it's big.


Here's another approach you might be interested in.

http://k6mhe.com/files/ssfm.pdf

73, Danny

In my many years I have come to a conclusion that one
useless man is a shame, two is a law firm, and three
or more is a congress. - John Adams

email: k6mheatarrldotnet
http://www.k6mhe.com/