"Cecil Moore" wrote
Richard Fry wrote:
* the peak "free space" gain of the monopole and its image is increas-
ed 3dB, because all radiation from it is confined to one hemisphere
(above the ground).

Remember, that's for perfect ground only (and maybe salt
water ground). If one buries half of a dipole in earth
ground, one loses most of that 3 dB to the ground.
____________

According to the empirical results of AM broadcast radiators, and also Roy
Lewallen's EZNEC numbers in his last post in this thread, the ground plane
itself doesn't need to be perfect, or maybe salt water to realize the gain
improvement. It's just that a very low resistance connection to it must
exist for the vertical to work against.

RF