All good info flowing: Remember, ground loops can appear on an AC ground
system whose lengths in a loop, before getting to the real ground, is odd
multiples of a quarter wave length at a frequency. I think that was the
concern. RF reference is obtained with short runs to an earth. But, in
some locations I have lived, even that earth is inadequate at both AC and
RF. Such is true in extreme desert or tropic conditions. The desert may
have sand that is more insulator than conductor. The tropics near equator
have daily rain that leaches all conductive salts from the earth, making its
impedance high at even 50 and 60 Hz much less RF. In 9M2 land, for example,
utility had to put down 10 ground rods where we only put in one, for an
earth rod. They would be bonded to lower the resistance of the whole.
73, Stuart K5KVH
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