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Old September 16th 06, 03:22 PM posted to rec.radio.amateur.antenna
Jeff Caird Jeff Caird is offline
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First recorded activity by RadioBanter: Sep 2006
Posts: 2
Default Endfeed vertical halfvawe antenna

"J. Kragh" wrote in
k:

Togethere wih a fellow amateur I am trying to design an endfeed
halfvawe vertical antenna for 50 MHz.

We have encountered som problems regarding the impedance match in the
feedpoint. I have surveyed the ARRL Antenna Book and Antennebuch (a
German antenna book very popular in Europe). The properties of the
antenna and its impedance is well understood. The missing point is how
to realise the matching network

In order to avoid reinventing the whee: Does anybody have some good
links to study practical realisations of the matching network?

vy 73

Joergen, OZ7TA



An endfed halfwave has inductive reactance, ISTR. If you add another 1/8
wave to it, you reverse the sign of the reactance, thereby allowing an
inductance to tune out the reactance. Ground one end of the inductor and
tap down with the coax center conductor for a 50 ohm match--Voila! A 5/8
wave vertical!

Jeff