Cecil Moore wrote:
Gene Fuller wrote:
You don't believe in superposition, do you? It is discussed in lots of
books if you want to understand.

Do you believe Jim's argument that two coherent EM
waves of equal magnitudes and opposite phases traveling
collinearly in the same direction in a transmission line
can never be canceled? If Jim is right, we can toss the
s-parameter analysis in the garbage can and join Roy in
calling it gobbledigook (sic).

Cecil,

Never is a long time. And I am sure you would slip away from free space
or a linear medium to provide some counter example as soon as I agreed.

I agree with Jim and Roy, and most of the rest of the world.
Electromagnetic waves, or photons if you prefer, simply do not interact
without the assistance of interfaces, discontinuities, or a non-linear
medium. Interference is a result from linear superposition. No waves are
harmed in the process.

At interfaces and discontinuities lots of things can happen. There are
well-established techniques for analyzing those things. There is no law
of "conservation of waves", however. There is also no law that says all
of the individual component waves you may choose to create need to have
some sort of detailed energy balance. I have explained several times how
the conservation of energy law works, but you seem to disbelieve me.
(Hint: I did not make this stuff up. I gave you direct quotes from very
reliable sources.)

Since you keep bringing up s-parameters, with the implication that they
provide some new truth, perhaps you might go back and re-read AN-95-1.

From page 7 of the slide version:

"If other independent and dependent variables had been chosen, the
network would have been described, as before, by two linear equations
similar to equations 1 and 2, except that the variables and the
parameters describing their relationships would be different. However,
all parameter sets contain the same information about a network, and it
is always possible to calculate any set in terms of any other set."

The other variables described earlier in the note include voltage and
current. Again, we come to my old standby, mathematical convenience.
S-parameters are very useful, but they bring nothing new to the physical
reality.

73,
Gene
W4SZ