On Jun 1, 8:10*am, K1TTT wrote:
what exactly is the 'interaction' *and why is it unique to that
special coherent, collimated, etc, case?

Is it not obvious that when two reflected waves cancel in one
direction, as at the surface of a 1/4WL thin-film coating on glass,
and their combined EM energy is redistributed in the opposite
direction, that those two waves have interacted, i.e. have suffered a
permanent change and have lost their original identities?

Is it not obvious that when two waves are traveling two different
paths where the incident angle is, e.g. two degrees, that those two
waves will superpose and interfere throughout a certain space after
which they emerge intact, unaffected, and have obviously not
interacted, i.e. they suffered no permanent change and have maintained
their original identities?

Did superposition occur in both cases? Yes. Did interference occur in
both cases? Yes. Did wave cancellation occur in both cases? No, just
in the non-reflective glass case.

Consider a transmission line with an SWR of 5.83:1. The sourced power
is 100 watts. The forward power is 200 watts. The reflected power is
100 watts. All of the reflected power is redistributed back toward the
load at a Z0-match through reflection and wave cancellation. Zero
reflected power is incident upon the source.

Does the 100w source wave lose its identity when it merges with the
100w of redistributed reflected wave to become the 200w forward wave?
Is the steady-state load energy coming from the source wave or the
redistributed reflected wave or both? Seems to me, it is obvious that
the two original component waves have interacted and lost their
original identities for good if they are pure coherent sine waves
traveling in the same direction confined to a coaxial transmission
line.
--
73, Cecil, w5dxp.com