On Jun 17, 5:08*pm, K1TTT wrote:
but you have already admitted that it is the only mechanism... though
you will now undoubtedly argue against yourself. * em wave reflection
IS the only mechanism for redistributing rf energy, you admitted that
when you agreed that superposition of the waves is the mechanism that
causes the interference in the first place.

Superposition and reflection are NOT the same mechanism. You are
totally confused about what I have said. Wave REFLECTION (of one wave)
is not caused by SUPERPOSITION (of two waves) and vice versa. Wave
reflection happens to a single wave when it encounters an impedance
discontinuity. Superposition requires two or more waves. They are
clearly two completely different mechanisms. So I will repeat what I
said befo

There are two mechanisms for redistributing the reflected energy back
toward the load.

1. The re-reflection of the SINGLE reflected wave from the load at an
impedance discontinuity associated with the power reflection
coefficient, e.g. 0.5 in my earlier example. Thus in that earlier
example, 1/2 of the reflected energy from the load is re-reflected
back toward the load and joins the forward wave toward the load. That
leaves 1/2 of the reflected energy that is transmitted through the
impedance discontinuity toward the source without being reflected.

The second energy redistribution mechanism occurs associated with
superposition of MULTIPLE WAVES.

2. The percentage of the reflected energy from the load that is
transmitted through the impedance discontinuity toward the source
superposes with the reflection of the source forward wave from the
impedance discontinuity. In my earlier example, the following two
wavefronts superpose in the direction of the source.

Pfor1(rho^2) = 50w and Pref2(1-rho^2) = 50w

Pref1 = 50w + 50w - 2*SQRT(50w*50w) = 0

This is the second mechanism (wave cancellation) that redistributes
the energy in the canceled wavefronts back toward the load. This step
2 is technically NOT a reflection since it involves two waves. This is
the step that the RF gurus are missing.

I really wish you understood the s-parameter equations which are
easier to discuss than the above RF equations.

In the s-parameter equation:

b2 = s21*a1 + s22*a2

the term, s22*a2, is the SINGLE WAVE re-reflection term, i.e. a2 is
the reflected voltage from the load.

In the other s-parameter equation:

b1 = s11*a1 + s12*a2 = 0

s11*a1 and s12*a2 are the TWO WAVEFRONTS that superpose to zero, i.e.
engage in wave cancellation.
--
73, Cecil, w5dxp.com