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POLARITY
OF THE COAX CONNECTION FOR J-POLE ANTENNAS
QRZ
Forum discussion on the polarity of the coax
connection for J-pole antennas. Not all comments have been reported
from the discussion.
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Original question
raised by myself:
I can't see that it makes much
difference, but is there any deference which way the coax is
connected to a J pole antenna. Is it better to have the centre of
the coax connected to the main element or the stub?
I notice that most if not all J pole designs on the net have the
centre of the coax connected to the main element, however when I
refer to a 1977 ARRL antenna book it has it connected the other way.
Is there any difference?
Mike W0BTU
commented:
Hello Peter,
I would explain more, but it's 3:15 AM here in Missouri.
Do a search for J-pole in the qrz.com forums. You'll find that it
works, but it has a feedline radiation problem.
__________________
73, Mike
www.w0btu.com
W8JI commented:
Look at patterns at the bottom of
this page:
http://www.w8ji.com/end-fed_vertical...ontal_zepp.htm
See exert below:
You'll see the feedline or mast
grounds directly to what everyone assumes is a "zero
voltage" point. This is the electrical equivalent of any J-pole
with the coax connected in series with the feedpoint, and the
shorter leg connected to the shield. The shield can be connected to
any supporting mast with any change in results. Here is the
resulting pattern:
Shorter leg to shield:
Longer leg to shield:
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last revised 12 March 2022
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