Re: [TowerTalk] Vertcal Dipole

[Bill Tippett <btippett@alum.mit.edu>]

K0PYK wrote:
>Has any made a vertical dipole (lets say for 20
meters) where it is end fed with coax.

        Yes but why not use a simple LC matching circuit?
The following circuits work best with a single 1/4 wl
radial counterpoise in addition to the 1/2 wl radiator:

http://www.qsl.net/aa5tb/efha.html
http://www.qsl.net/aa5tb/halfwave.html
http://www.w0ch.net/field_antenna/field_antenna.htm
http://www.arsqrp.com/ars/pages/back_issues/2000_text/0100_text/film.html

I built the latter faster than it took to read all
the posts about this!

        I've also tried using a Z-match tuner (Emtech ZM-2)
to directly feed a 1/2 wl radiator (no radial) which
worked fine.  However, I wanted to eliminate any tuner
for ultra-lightweight backpack operations.

        Par Electronics offers the following series of
End-Fed 1/2 wave antennas which require NO radial
and NO tuner.  I've been using the EF-20/40 which
works very well with direct feed from my QRP rig.
With the EF-20/40 plus KD1JV's AT Sprint 2, I have a
complete 20/40 station including transceiver, battery,
earphones, paddle and antenna (no tuner needed) that
weighs ~1 lb total.

http://www.universal-radio.com/catalog/hamwire/4456.html

                                        73,  Bill  W4ZV




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