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Old October 3rd 07, 07:35 AM posted to rec.radio.amateur.antenna
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Posts: 7
Default j-pole 5/8 wave


"Cecil Moore" schreef in bericht
t...
michel wrote:
Should it be that simple? I understood from other posters that it will
not work with the 1/4 wave stub..


A 1/2WL + (1/4WL series stub) is a resonant Zepp.
When the stub is shorted at the bottom and tapped
for 50 ohms, it becomes a typical J-Pole.

A 5/8WL + (1/5WL series stub) is a resonant Extended
Zepp. There is only one resonant point and it may
not be at 50 ohms but it may be close enough. You
won't know till you try it. The feedpoint impedance
can be varied by varying the spacing between the
stub elements.

A 5/8WL + (1/4WL series stub) is non-resonant.
Anywhere you tap on the stub will result in some
reactance. There's really no reason to build
this inferior design.
--


Cecil,

That is some clear information!! The 5/8 wave version needs a shorted stub
as well?


 
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