Lynn
All things being equal, a truly guyed tower (i.e. conductive and
uninsulated) will have a voltage gradient between top and bottom
of approximately 1/3rd that of a tower which is either
freestanding or the guys are nonconductive or have insulators in
them. Note that the TOTAL current will be the same in both cases
as lightning is a constant current generator. But what you are
achieving with the guys is current sharing (parallel paths).
Since Vd=L (di/dt), the Vd associated with the tower will be less
because the di is less down the tower.
BTW, 2 or 3 ground rods at the base of the tower is insufficient
as a good lightning ground. The scenario in the first paragraph
also assumes a proper lightning ground is employed where the guys
are anchored. We are, nevertheless, comparing apples to apples
based upon the scenario you presented.
Several years ago, the myth that uninsulated conductive guys
would affect the beam pattern was dispelled in a QST article.
Hope this helps!
Sincerely & 73,
Bob Wanderer (AA0CY)
Senior Applications Engineer
PolyPhaser Corp.
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