[TowerTalk] Lightning zone of protection?

[George VE3YV]

As an anecdote FWIW:  When I was in university, I worked briefly as a
student engineer (the guy that sat there and signed the logs because he/she
had the commercial license then required) at the university radio station.
The AM transmitter had a shunt fed tower in an open field next to the river
at the edge of town.  Routinely during thunderstorms, the ground or a tree
nearby would be hit rather than the 120 ft tower, the highest point in the
vicinity.  You could watch (remotely) the lightning hit other targets in the
area (including the lowest point, the river) and see the RF current meter
needle bounce up and down.  Direct hits would "dump" (turn off) the
transmitter which required manual restart.

 

Seemed that a grounded tower, the highest point for some distance, would not
necessarily provide protection to something much lower.  If the tower got
struck, it was after it had rained a while, especially downpours, suggesting
that the tower didn't have a low impedance path to ground until the rain
improved the earth conductivity.  It's been too long to remember what the
angle of height to nearest stand of trees was to comment on cone zone.  

 

Of course, YKMV.

 

73, George VE3YV / K8HI