Cecil Moore wrote:
Gene Fuller wrote:
All we need now is that you also understand that waves flowing in the
SAME direction do NOT interact unless there is an interface or other
discontinuity.

Please stop implying things that I have never said. When I
asserted that reflections only happen at a physical impedance
discontinuity, that implies that interaction can only happen
at a physical impedance discontinuity. It is impossible to
get two coherent waves flowing in the same direction except
at a physical impedance discontinuity.

Assume b1 = s11(a1) + a12(s2) = 0

What I have said is that s11(a1) and s12(a2) are wave components
that cancel without ever being incident upon an impedance discontinuity.
Those two wave components originate at the impedance discontinuity
flowing *AWAY FROM* the impedance discontinuity. They are canceled
in a delta-t, i.e. a very short time. Those two waves are the result
of interaction at the impedance discontinuity but neither of them
ever interacted with the impedance discontinuity because they
originated at the impedance discontinuity.
--
73, Cecil, w5dxp.com


Cecil,

I am familiar with all sorts of weird and wonderful things that happen
on surfaces and really close to interfaces and discontinuities. However,
classical transmission line theory does not deal with any of those
things. I don't believe any of the recent discussions on RRAA have dealt
with these close-in effects either.

Where are the equations that describe this "delta-t" stuff that you keep
bringing up? How long is delta-t? What justification do you have for
saying that the waves start out from some point and then shortly
thereafter decide to cancel? Do they annihilate each other suddenly or
is the interaction gradual from time zero up to delta-t? Do you have any
references for this behavior? I scanned the Melles Griot tutorial info
and the FSU website, but I couldn't find anything about delta-t.

Inquiring minds want to know.

73,
Gene
W4SZ