Topband: Question Re: Coax Shield vs. Ground.

Tom Rauch w8ji at contesting.com
Thu Dec 28 20:58:44 EST 2006


How do we isolate the coax shield from the radial system? >>

I'm specifically talking about receiving systems. An 
isolation transformer is cheap and easy, and since most 
receiving antennas have poor grounds or no grounds, they 
should never be tied into the coax shield...which would 
allow common mode currents to pass. I just can't imagine why 
anyone would build a receiving system where the coax can 
contribute signal to the receiving antenna through a 
shield-to-antenna path.

In transmitting systems elevated radials should never have a 
ground path. Grounding elevated radials reduces efficiency.

If the house has a lot of noise and you receive on the 
transmitting antenna you might not want to directly ground 
the antenna ground system to the house. This is especially 
true with a small radial system.

73 Tom 




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