My understanding is that the antenna ground wire is to provide an
"alternate" path for the very large, near instantaneous current (either
from ground to the sky/lightnining or from the lightning to the ground,
depending on the difference in the voltage potentials) that occurs when the
lightning "strikes" the metal mast.

Too small a conductor and it will be quickly vaporized leaving the current
to find its way to ground via some other (more destructive) path. Even if
the ground wire is of sufficient diameter to withstand the lightning strike,
it also needs to be as low of a resistance on that path as possible since
some portion of the current will nonetheless follow the path down the coax
based on the impedances seen in those two "parallel" paths to ground. The
goal here is simply to minimize any current down the coax so proper
attention needs to be given to the construction and length of the ground
conductor as well as the terminations on both ends too.

Bob

wrote in message
...
Someone mention using a thick wire for grounding..I was wondering if
that really was needed..by grounding the antenna isn't that just
changing the charge potential between the antenna and the ground.