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[TenTec] RF Ground

To: Discussion of Ten-Tec Equipment <tentec@contesting.com>
Subject: [TenTec] RF Ground
From: Jim Brown <k9yc@audiosystemsgroup.com>
Reply-to: Discussion of Ten-Tec Equipment <tentec@contesting.com>
Date: Fri, 03 Apr 2009 21:35:11 -0700
List-post: <tentec@contesting.com">mailto:tentec@contesting.com>
> Do recall that any station ground has length and inductance and impedance. 
> It may be a good DC ground as it has low resistance, but is it a good RF 
> ground?  In almost any condition, the station is above RF ground.  For 
> example, a station ground that is some 16 ft in length puts the station at 
> 1/4 wave above ground on 20M.  That 1/4 wave ground wire can radiate or 
> receive noise just like an antenna.
The words "RF ground" have NO MEANING in science. They are a fignewton 
of fuzzy thinking. A connection to EARTH is totally irrelevant for a 
radio transmitter, receiver, or antenna. A connection to earth is NOT 
part of a solution to RF interference, hum, buzz, or noise.  A 
connection to earth does not make an antenna work better.  It only 
provides lightning protection.  That's very important, of course,  and 
to do that,  ALL  ground rods must be bonded together by that low 
impedance path, and all wiring that enters a building must have its 
lightning protection bonded together and to that network of ground rods. 

For two reasons, that bonding together also minimizes hum and buzz 
related to the power system.. First, pin 1 problems. Second, unbalanced 
wiring. Both couple noise current into equipment.

The EARTH is a LOUSY antenna element, because it is lossy (resistive). 
Any RF current flowing in the earth is lost as heat. We use radials with 
vertical antennas to prevent current from flowing in the earth, and 
allow it to flow in low resistance copper instead.  The vertical antenna 
is trying to produce an EM field, and the radials complete the path for 
that field (and for the antenna current). Only a few resonant radials 
can serve that purpose if they are high above the earth, but it takes 
MANY radials to do that well if they are very close to the earth. Those 
radials are not RF GROUND. Over the years, we have confused ourselves by 
calling them a ground system, or a "ground plane." They are not. They 
are part of the antenna! 


Jim Brown K9YC
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