To: <towertalk@contesting.com>
> Date: Fri, 29 May 1998 00:39:58 -0700
> From: Kurt Andress <NI6W@yagistress.minden.nv.us>
Hi All,
> A lightning strike does not respect "A nice low impedence path from the
> tower to the house." It just has a @#@#$$%^& of a lot of energy trying to
> find a ground connection. It is merely looking for the lowest inductance
> path to a low resistance connection to the earth ground!
It's looking for that collection or source of opposing charges.
In my installation, I prefer it do that out at the tower.
> Impedance may be great for RF grounding, but lightning doesn't care!
Impedance isn't great for any grounding--RF or otherwise, the lack of
impedance is the goal.
> Flat copper conductors present a lower inductance path than round ones!
Can you give me a reference for that? I've been looking for years,
and find no data on conductor shape vs inductance.
I do know...
Smooth conductors have less resistance and impedance (that is
published data and evident in practical applications). Braiding is
not a good choice when low impedance is required for RF or
lightning.
In flat wide conductors spaced some distance from an opposing current
carrying conductor, excited with rapidly time-varying currents,
current bunches up at the very edges with very little current down
the center (measured it with a current probe and also as lower
Q than a round conductor of the same surface area). The wide
strip might as well be a pair of parallel conductors with air in
between for RF.
73, Tom W8JI
w8ji.tom@MCIONE.com
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