[Antennas] Re: [RFI] Long distance grounding

[Danny Richardson]

At 04:47 AM 6/12/2007, Tom wrote:
>[snip]
>As for RF, and I'm speaking of RF and not lightning, it is a
>common myth that equipment with coaxial feedlines or
>properly balanced two conductor lines needs an RF ground.
>Unless the equipment or antenna systems have a serious
>design shortfall there isn't any need for an RF ground. It's
>always better to figure out why we have RF problems then to
>put a band-aide on the real problem while the real problem
>simmers in the background.
>
>That ground running around on the desk or in the radio room
>should be for AC power source safety. If we have to use it
>for RF or lightning we should probably rethink the system.

The problem is 99% of the time our "balanced" antennas aren't 
balanced. Ian White GM3SEK, in his In Practice column "Myths of 
Balance" Dec 2005 ( http://k6mhe.com/sub/BalancedFeedLine.pdf ) 
points this out very well.

Using Kevin Schmidt, W9CF's measurement examples in his paper 
"Putting a Balun and a Tuner Together" ( 
http://fermi.la.asu.edu/w9cf/articles/balun/index.html ) I measured 
my tuned fed antenna system here ( 
http://k6mhe.com/sub/Balance_Z_L1-L2.gif ) and see I have about 10% 
imbalance on twenty meters (where I am experiencing some common mode 
problems).

Comments?

73,
Danny, K6MHE





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