"Owen Duffy" wrote
One good pickup was the functions for predicting the low frequency
resistance of shallow buried radials (which is relevant when radial
wires are required to provide a level of power / lightning protection.
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For those using buried radials as one terminal of a vertical monopole...

The only path consisting of physical conductors that can exist between a
series-fed vertical monopole and buried, uninsulated radials is through the
PA output, and the antenna matching network at the tower base. This is not
adequate to control/prevent system damage from lightning.

Three added techniques are used in most MW broadcast applications:

1. A "static drain choke" is installed between the tower base and the
junction of the radials.

2. An arc gap is installed across the base insulator and set to flash over
at some margin above normal peak voltage

3. The tx contains r-f phase sensors that kill tx output for a few
milliseconds after an arc is sensed, so as not to sustain it.

RF