[BC] AM transmitter lightning sensitivity issue

[Gary Peterson]

" Having MANY points, those tower-mounted static 
dissipators are quite effective at discharging static into the air/cloud,
thus 
preventing it from building up enough energy to initiate a strike.
Willie... "

When I taught chemistry and physics, I spent considerable time experimenting
with both a Van de Graaff generator and a Wimshurst static generator.  My
observations are in agreement with Willie's.

It seems to me that there must be a point (no pun intended) where the number
of sharp points begins to mimic the surface of a smooth object, such as a
sphere.  This thinking is similar to the modeling of a tower, with enough
folded-unipole drop wires, as a cylinder.  Intuitively, this would be
counterproductive.  Having a sphere or a flat plate on top of an object
would seem to tend to encourage a charge build up.  I have no idea how one
would calculate the number of sharp points, beyond which protection actually
decreases.

This was my thinking on my amateur antenna installation.  I have a very
large five element, HF Yagi on top of a 65' tower.  I felt that this would,
electrically, resemble a flat, conductive plate.  Therefore, I have 6' of
mast, with a very sharp point, projecting above the antenna's boom.  There's
lots of visible corona activity up there when storms are building.  No
evidence of a strike in the last twenty years.  With our low humidity, we do
get plenty of potent lightning.  Maybe I'm just lucky.

Gary, KØCX
CE KFXS, KOUT, KKMK, KRCS, KKLS & KBHB
Rapid City, SD