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Old February 24th 10, 11:14 PM posted to rec.radio.amateur.antenna
Owen Duffy Owen Duffy is offline
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First recorded activity by RadioBanter: Dec 2006
Posts: 1,169
Default Two coax as substitute for open line

steveeh131047 wrote in
:
The application is no secret - the first paragraph in my linked page
explains it.


I missed that!

I was looking for line with a Zo in the range 50ohms-70ohms that could
be used for the band interconnects on the hexbeam. Arguably, balanced
line would be easier to handle, and might have some common-mode
advantages. Total length is about 4ft so loss is not an issue. It


I am not so sure there would be much difference.

would need to be very easily replicated, using materials readily
available to constructors world-wide.


If you tried my calculator for the square tubes, you would have found
that you get lower Zo for the same D/d ration as for round tubes. For
example, a pair of 12mm tubes clamped together with 2mm spacing gives Zo
of around 50 ohms. If such an element could be used to replace one of the
spreaders, then you have neat solution... but it would take some custom
moulding to support such a spreader on the hub.


At the end of the day it became more of a "self learning" exercise
than a serious quest !


Well, that is a serious quest.

Cheers
Owen


73,
Steve G3TXQ