Jim Kelley wrote:
In the case of a radiator, the emanating energy is a result of the
superposition of fields radiated by the currents traveling on the
antenna. I could be mistaken, but it seems to me that superposition
should yield the same result by either approach. If so, then for a
single element radiator, the field pattern would appear as though a
standing wave on the antenna had created the field.

On a 1/2WL dipole, for instance, of the total amount of
average energy existing on the antenna, approximately
80% of that energy is in the standing wave. The other
20% is radiated as real power presumably from the traveling
waves because standing waves contain no real power. Like
impedance transformation on a transmission line with
reflections, the standing wave on the dipole is used
to transform the relatively high Z0 of the antenna wire
down to the relatively low feedpoint impedance of the
antenna. The source re-supplies the radiated power to
keep the average standing wave energy constant.

Since the standing wave energy is being used to transform
impedances, it cannot also be used for radiation purposes -
like the energy in a standing wave on a transmission line
cannot be used both to transform impedances and to heat
up a load.
--
73, Cecil http://www.w5dxp.com