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[TowerTalk] Re:grounding bulkhead

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Subject: [TowerTalk] Re:grounding bulkhead
From: (Martin Ellis)
Date: Fri, 14 Nov 1997 21:06:07 +1300
Hello Charles,
My vote is as follows, and for the moment I am ignoring
lightning issues:

Provided there is no RF on the outside of the coax feedlines,
they may be joined or grounded at any point along their length.

My reason for this statement is simple:
W7EL has stated that there are three paths of interest in
a coax feedline: the centre conductor, the inner surface of the
braid, and the outer surface of the braid.  The current on the inner
conductor and the inside of the braid is always equal and opposite, 
which cancels any external radiation. 
The purpose of a current-type balun at the antenna is to avoid the
presence of RF on the outside of the braid, and if this is achieved,
the outside of the braid is at ground potential along its length.

Hope this is of help,
Martin ZL1ANJ

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