Jim Kelley wrote:
What has been known since long before you were born is that only direct
interaction with matter causes EM waves to reflect.

Would you say the changing characteristic impedance between
two waveguides in outer space is a direct interaction
with matter? There is no matter inside the waveguide with
which to interact.

However, I am wondering if I am using the wrong word when
I say interference can cause reflections. Since the same
thing happens with scattering S-parameters, it may be
a 180 degree refraction instead of a 180 degree reflection.
I'll have to take a look at the math.

But no matter what it is called, the results are the same.
"A rose by any other name ..."
--
73, Cecil http://www.w5dxp.com