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Power divider for X-yagis



Hello to you all.

When buidling a phasing harness for (switchable) circularly polarised
crossed-Yagis one needs a device to split the line from the TRX to the
two legs of the yagi.
In the ARRL antenna handbook (and others) I see quart lambda 36 ohm
transformers in the figures.
In my current state of confusion I have the following questions.

1- this 36 ohm transformer is apparently a square pipe with a round rod
to which three N sockets connect. Where do I find "the right" formula
for calculating the characteristic impendance for square pipe with a
round rod in it. I coulnd't find it in any of the ARRL or RSGB books I
have. (but I might have gone blind for just this :-)) On the net I found
different formulas.

2- this 36 ohm transformer correctly transforms the two parallel
impedances of the 50ohm lines to the legs of the yagi (so 25 ohms
combined) to the 50 ohms of the TRX. But.....seen from the yagi there is
a mis-match, impacting the received signal.
Wouldn't it be better to use a Wilkinson power divider/combiner, from
either (70.7 ohm) square pipe or coax? There isn't much difference in
the work to make one or the other, so I might as well do this the best
way.

I really would appreciate some help here.

Thanks

Joop, PA1JAV


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