On Mon, 12 Nov 2007 14:33:10 GMT, "Nick" wrote:

Would it give more protection / solve the problem, if I encased it
in a fibreglass yacht mast which I happen to have ?

Hi Nick,

No, it wouldn't.

Make the antenna shorter, and surround it with taller, nearby grounded
vertical conductors for the lightning to select in preference. For
more protection, connect the tops of the taller conductors over the
antenna.

Of course, this advice reduces to putting the antenna in a grounded
cage that takes the hit. Unfortunately it also renders the antenna
deaf.

Moral: Trying to stop the lightning from hitting your antenna also
stops RF.

[Hint: if you are going to stop it with a super glom of insulation,
like fiberglass, consider that this insulation is inferior to a
bajillion miles of air already there surrounding the antenna. That
doesn't slow down lightning much does it?]

73's
Richard Clark, KB7QHC