To: | Jim Brown <jim@audiosystemsgroup.com>,"Tower Talk List" <towertalk@contesting.com> |
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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 _______________________________________________ See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless Weather Stations", and lot's more. Call Toll Free, 1-800-333-9041 with any questions and ask for Sherman, W2FLA. _______________________________________________ TowerTalk mailing list TowerTalk@contesting.com http://lists.contesting.com/mailman/listinfo/towertalk |
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