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Re: [TowerTalk] Water tower omni

To: TowerTalk <>
Subject: Re: [TowerTalk] Water tower omni
From: Red <>
Date: Tue, 04 Jul 2006 09:19:28 -0500
List-post: <>
Hi, TTs;

Be aware that antennas on the sides of tall structures are not protected 
from lightning strikes by the structure.  The "cone of protection" 
concept applies only to relatively short structures and lightning rods.  
A more correct concept for protection offered by tall, over 20 to 50 
meters, structures is the "rolling ball" concept.  A lightning leader 
descending toward earth within 20 to 50 meters to the side of such 
structures may reach a point below the top of the structure and then 
turn toward the structure.

For more information, read, "Lightning: Physics and Effects," Dr. 
Vladimir A. Rakov and Dr. Martin A. Uman.  2003. Cambridge  University 
Press.  This is an undergraduate text, not too technical , that provides 
useful explanations of why lightning does what it does as well as the 
latest findings and data from lightning research and information 
regarding lightning protection.  It is not commonly available at local 
public libraries.  I borrowed a copy via inter-library loan from U of MN.

I have observed one such strike to about the midpoint of a TV antenna 
tower near my home.

73 de WOØW

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