[TowerTalk] Grounding Question - Rooftops

[Jim Brown]

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