On Fri, 13 Jul 2007 11:03:23 GMT, "Dave" wrote:

The problem is that in the event of a lightning strike, nothing is at
earth
potential!

and a corrolary of this: there is no such thing as an 'rf ground'.

Two of the oddest statements (barring Gaussian arrays) that have ever
come down the pike.

1. WHAT problem?
2. no such THING?

1. Where are you standing where there is no earth potential in
relation to lightning's potential? Ground may elevate locally in
potential due to current and resistance at the strike point, but if
you are standing there (sans obvious catastrophic effects); your
potential rises in like manner and the sense of ground is preserved.
This is the entire point of a grounding system of equipotential
connections.

2. RF ground is deliberately constructed by the same motivations, at
a higher frequency. Given that lightning's RF pulse consists of a
prominant 1 µS event, its RF content is very similar to one of
thousands of AM systems that have grounds designed to exhibit a very
low loss. Excluding the catastrophic event, RF ground systems are
designed for other frequencies conforming to the identical
motivations.

73's
Richard Clark, KB7QHC