Dave wrote:
"and a corrolary of this (----in the event of a lightning strike,
nothing is at earth potential):
there is no such thing as an "rf ground"."

I`ve worked at a number of broadcast stations, none of which suffered an
iota of lightning damage, though often removed from the air
automatically for an instant by a lightning instigated overload. I`m
convinced the (120) radials around each tower in their antenna arrays
diverted lightning strikes to earth and the strike energy never entered
the transmitter building.

Brown, Lewis, and Epstein showed that earth radials can lower the
resistance of the RF ground connection to the vanishing point (lower
than the earth`s resistance in many cases, think parallel paths).
Resistance is low for lower frequencies and DC too. Skin effect goes
down with frequency and resonance in radials is eliminated by ground
loss.

Best regards, Richard Harrison, KB5WZI