[TowerTalk] Grounding Question - Rooftops
Jim Brown
jim at audiosystemsgroup.com
Mon Aug 6 10:16:08 EDT 2007
On Mon, 06 Aug 2007 09:02:15 -0400, Cedrick 'Fred' Johnson - WT2P wrote:
>Any suggestions for
>dealing with "high altitude" grounding and lightning arrestors on the
>coax feeds?
Both for lightining protection, AND to act as a counterpoise for your
vertical, the best "ground" by far is the steel structure of the building.
It has a relatively low impedance to earth by virtue of there being multiple
paths in parallel. I would concentrate on making a good connection to the
building near the base of the vertical and whatever holds up your tribander.
One caution though. There WILL be interaction between the vertical and any
other conductors around it, especially vertical ones (like the support for
the tribander). That interaction could include detuning it and modifying the
horizontal pattern. The greatest interaction will be on those bands where
the vertical elements are some multiple of a quarter wave.
With a good bond at the base of the vertical to the building, I would expect
it to work pretty well.
73,
Jim Brown K9YC
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