Keith Dysart wrote:
So then, for "two coherent isotropic radiator",
it is your contention that "far from the antennas
it is "interference" that causes the variation in field
strength, but that on the line drawn between the two
antennas some other mechanism is responsible".

Please define "field strength". The total average
power density along a line drawn between the two
point sources is constant, i.e. the average sum
of the energy in the E-field and H-field is
constant. If you are defining "field strength"
as only the E-field, of course standing waves
are the cause, not interference, as defined by
Hecht in "Optics".
--
73, Cecil http://www.w5dxp.com