Richard Harrison wrote:
I was wrong when I wrote waves would be exhibitable on demand were they
annhilated. Cecil was right. It makes no difference whether two equal
and opposite signals are received or no signal is received. Same result.

Which means that if two coherent waves flowing in the same direction are
completely cancelled, the E-fields and the H-fields in that direction are
also cancelled and therefore, zero energy propagates in that direction.

So the question remains: What happens to the energy in those two rearward-
traveling cancelled waves? Melles-Griot says the energy is not lost and
instead appears as enhanced intensity in the forward-traveling wave. From
rearward-traveling energy to forward-traveling energy certainly sounds
like a direction reversal to me.

"Enhanced Intensity" is another name for constructive interference and
in a matched system, it is "total constructive interference". "Complete
Wave Cancellation" is another name for "total destructive interference".

Bottom line: In a Z0-matched system, the reflected energy flows rearward
to the Z0-match point, changes direction at the Z0-match point (because of
interference), and joins the forward energy wave flowing toward the load.

Anyone got a better word than "re-reflected" to describe that event?
From looking at a diagram of laser light encountering a perfect 1/4WL
thin-film coating on glass, it is apparent that all the rearward-traveling
reflected irradiance (power) encounters a conjugate "mirror" and joins the
forward-traveling energy wave.
--
73, Cecil http://www.qsl.net/w5dxp



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