At 07:54 AM 5/15/02 -0400, N6ZO@aol.com wrote:
>I
>was told that if there was a lightning strike in the area, the navy WANTED
>to be sure that any strike to be taken by the towers and not the sub. Don't
>know how often they are successful at taking lightning strikes but there are
>no signs warning people away from the towers.
>
>Wonder what else they did to those towers to ATTRACT lightning?
Chapter 15 of the original Polyphaser "Grounds" book describes a radius of
protection that is conferred by a grounded tower, based on the physics of
the step leader that precedes lightning. They say that the tower will take
the hit and confer 96 percent protection on things in the protected
zone. Presumably it's the same, though more complex, for those 250-foot
towers with the conductor between. If I read the book correctly, objects
up to 100 feet in height directly under the horizontal wire or adjacent to
either tower are protected to this level of confidence, declining to zero
protection at 150 feet away from the wire or either tower.
On the other hand, I recall an anecdote from W0UN describing how severe
lightning storms would come across the Colorado prairie toward his field of
towers, striking frequently as they came, but would stop as they approached
his towers, and resume once past them. That sounds as if some sort of
other lightning prevention mechanism was at work, and perhaps the
Polyphaser discussion isn't the whole story.
73, Pete N4ZR
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