Cecil Moore wrote:

Continuing and calculating interference energy at point 'y':

V1y = VF2(1-rho) = 96.58(0.732) = 70.7V (100W)

V2y will be VR3(rho) = 40.82(0.268) = 10.94V (2.39W)

VF3 = 70.7V + 10.94V = 81.65V. (133.33W)

The power equation at point 'y' looking toward the load is:

PF3 - P1y - P2y = constructive interference

Note that P2y + constructive interference = re-reflected power.

133.33W - 100W - 2.39W = +30.94W

A '+' sign on the interference term indicates constructive
interference.

There is 30.49 watts of constructive interference at 'y' looking
toward the load. That energy must come from somewhere.

Therefore, there is 30.49 watts of destructive interference at
'y' looking toward the source. The flow of energy from the
destructive interference event to the constructive interference
event is an interference-caused reflection.

The total re-reflected power at 'y' is 2.39W + 30.94W = 33.33W
In this case, everything except P1y is re-reflected. This is in
agreement with Walter Maxwell and in disagreement with Dr. Best.

V1x = VF1(1+rho) = 70.7V(1.268) = 89.6V (88.09W)

V2x = VR2(rho) = 25.9V(0.268) = 6.94V (0.556W)

VF2 = V1 + V2 = 89.64V + 6.94V = 96.58V (107.7W)

The power equation at point 'x' looking toward the load is:

PF2 - P1 - P2 = constructive interference

107.7W - 88.09W - 0.556W = +18.42W

The '+' sign tells us that there is 18.42 watts of constructive
interference at 'x' looking toward the load. That energy must
come from somewhere.

Therefore, there is 18.42 watts of destructive interference at
'x' looking toward the source. This is also an interference
reflection.

The total re-reflected power at 'x' is 0.556W + 18.42W = 18.98W
Everything except P1 is re-reflected at a match point.

Using the S-parameter equations:

b1 = s11(a1) + s12(a2)

b2 = s21(a1) + s22(a2)

s21(a1) is the only voltage term that doesn't get reflected
at least once.

s11(a1), s12(a2), and s22(a2) are all reflected terms. If the
energy in these terms winds up at the load, they have all been
re-reflected.
--
73, Cecil http://www.qsl.net/w5dxp



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