Richard Clark wrote:
I have a 100W transmitter, name me one antenna that will radiate more
than 100W from this source. Then we can put a "gain" figure to it.

The ONLY difference between antenna directivity and antenna gain, by
definition, is efficiency. Therefore, it logically follows that you
are asserting that no antenna possesses directivity. Care to prove
that outrageous assertion? Maybe you better stick to optics?
--
73, Cecil, W5DXP