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Re: [TenTec] RF Ground

To: Discussion of Ten-Tec Equipment <tentec@contesting.com>
Subject: Re: [TenTec] RF Ground
From: Martin Ewing <martin.s.ewing@gmail.com>
Reply-to: Discussion of Ten-Tec Equipment <tentec@contesting.com>
Date: Sat, 4 Apr 2009 11:52:15 -0400
List-post: <tentec@contesting.com">mailto:tentec@contesting.com>
Yes, but... It's still worth trying to establish a local RF "ground" --
ensuring that everything in your shack is bonded together.  No antenna
system is perfect, and many of us have some RF in our shacks.  Fortunately,
the same bonding is needed for lightning and AC safety reasons, although
inductance is not a worry at 60 Hz.

The ideal is a Faraday Cage - enclosing your shack in a (nearly) solid
conducting box.

73 Martin AA6E

On Sat, Apr 4, 2009 at 12:35 AM, Jim Brown <k9yc@audiosystemsgroup.com>wrote:

> >
> > 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!
> 73,
> Jim Brown K9YC
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