Dear James,

Thank you very much indeed for your thorough analysis.
The estimated 3 pF antenna capacitance is about right and is the same
as for a 30 cm long whip.

A 30 cm long whip and a 30 x 40 mm PCB antenna give the same signal
output.
However, I don't know if the induced voltage due to a near lightning
strike will be the same for both antennas. As the field strength is
proportial to the length of a whip, my guess is that for the PCB antenna
it probably is less. But this assumption might be totally wrong.

73,
Roelof Bakker, pa0rdt