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RE: [TowerTalk] Grounding, Lightning & corona discharge

To: Jim Brown <jim@audiosystemsgroup.com>,"Tower Talk List" <towertalk@contesting.com>
Subject: RE: [TowerTalk] Grounding, Lightning & corona discharge
From: Pete Smith <n4zr@contesting.com>
Date: Thu, 29 Jul 2004 16:17:32 -0400
List-post: <mailto:towertalk@contesting.com>
At 03:57 PM 7/29/2004, Jim Brown wrote:
When thinking about it, remember that the energy in lightning is NOT at
dc, it is around 1 MHz. The impedance of that path is primarily
INDUCTIVE REACTANCE, not resistance. Resistance (greatly
increased by  skin effect)  will certainly produce the I2R losses, but XL
will determine current!


I recall reading somewhere (I thought in Polyphaser material but can't find it there now, in a quick search) that there is meaningful energy in a typical lightning bolt that is effectively far higher frequency than that -- somewhere in the 100 MHz range -- because of the fast rise time of a typical strike. This was in connection with advice that ground wiring follow VHF precepts in being as straight and wide as possible to absolutely minimize inductance.

Fact or fiction? It would be a lot easier for me to improve my protective grounding if I could use copper strip but have a couple of right-angle bends in it.


73, Pete N4ZR
The World HF Contest Station Database
was updated on June 5, 2004
2728 contest stations at
www.pvrc.org/WCSD/WCSDsearch.htm


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