Would you agree that the earth is considered a zero potential reference
point when compared to things located on or flying above it ?
Would you agree that is true for both DC and AC ?
Would you agree that multiple paths in parallel, each with a finite
resistance, provide a smaller collective resistance (I should say impedance)
when connected in parallel ?
Would you agree that lightning is mostly RF ?
73 de Gary, AA2IZ
----- Original Message -----
From: "Jim Brown" <k9yc@audiosystemsgroup.com>
To: "Discussion of Ten-Tec Equipment" <tentec@contesting.com>
Sent: Saturday, April 04, 2009 12:35 AM
Subject: [TenTec] RF Ground
> >
>> 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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>
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