On Sun, 17 Aug 2008 13:07:29 -0500, Mike Gorniak wrote:
>Obviously, the radials are critical to the performance of the antenna.
>But it's the ground rods that protect the station from lightning damage.
Hi Mike,
Intuitively, the radials provide a capacitive connection to earth, while
the rods are part of a DC connection that includes both resistance and
inductance. As frequency increases, inductance dominates. Since lightning
is a broadband event (that is, DC to many MHz) with most of the energy
concentrated within several octaves centered around 1 MHz, one would expect
that capacitance to be of value WHEN the strike happens.
I'm not a lightning expert, but I'd want to see some science on that
(controlled studies, lots of installations and events analyzed
statistically, with peer review) before I would accept this statement as a
given. (It's entirely possible that this work exists, of course, I just
don't know about it.) The rods may have prevented damage in your situation,
or it could have been coincidence. What I WOULD accept is the DC connection
(the rods) minimizing the slow buildup of a DC charge that might lead to
the event.
73,
Jim Brown K9YC
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