k1drw wrote:
the vertical configuration: It seems then, that the 2nd half
of the cycle on the vertical (where the current flow is coming out of
the vertical element and into the radials) is practically worthless in
terms of radiating signal into the 'ether'.

Dennis, you got the simplified version. When current is
flowing into the antenna, electrons are flowing out of
the antenna. When current is flowing out of the antenna,
electrons are flowing into the antenna. Either way the
electrons are flowing, they are being accelerated for
part of the cycle. So RF radiation (photon generation)
occurs no matter which way the electrons are flowing.

In addition, the vertical is a standing wave antenna.
It actually has RF waves moving both directions at the
same time. There's the forward wave moving toward the
top of the antenna and the reflected wave moving from
the top back toward the feedpoint. The SWR on a 1/2
wavelength dipole is in the ballpark of 20:1.

For an antenna to be close to 100% efficient, it must
radiate equally during both half cycles.

You can blame Ben Franklin for current flowing the opposite
direction from the electron flow. He didn't know electrons
carried a negative charge. So by definition, current flows
from plus to minus but electrons actually flow from minus
to plus. In addition, RF current flow is associated with
the RF electromagnetic wave (photons) , not with the
electrons which move much slower than the speed of light.
--
73, Cecil http://www.w5dxp.com