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Old May 10th 11, 11:24 AM posted to rec.radio.amateur.antenna
Richard Fry Richard Fry is offline
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First recorded activity by RadioBanter: Jun 2006
Posts: 440
Default Transmitter Output Impedance

On May 9, 8:13*pm, walt wrote:
There is a specific correlation between source power,
forward power and reflected power, such that with a 100w source in a
50-ohm system, a 2:1 mismatch, when the reflected power is re-
reflected the forward power is 111.11w, reflected power is 11.111w,
and power absorbed in the load is 100w.


Walt -

If the load reflects 11.111... percent of the forward power, and 100%
of reflected power is re-reflected by the source, then how/why in your
example is the power absorbed by the load equal to the original
incident power of 100W?

A re-reflection for these conditions is not 100% absorbed by the load,
rather 11.111% of it is reflected back to the source. Only ~88.889%
of that first re-reflection is absorbed by the load. Ditto for all
further re-reflections of the first reflection.

Assuming no loss in the transmission line, and phase coherence at the
load for all forward power, wouldn't the load power accumulate per the
table below -- which shows the initial forward power absorbed by the
load with the first ten re-reflections of it by the source?

88.889 watts
1.23454321
0.137170096
0.015240969
0.001693424
0.000188156
2.09061E-05
2.32287E-06
2.58094E-07
2.86769E-08
3.18629E-09
- - - - - - - - - -
90.27785937 watts, total

Then the next question is what happened to the "missing" power?

RF