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Old June 16th 10, 06:25 PM posted to rec.radio.amateur.antenna
Owen Duffy Owen Duffy is offline
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First recorded activity by RadioBanter: Dec 2006
Posts: 1,169
Default Where does it go? (mismatched power)

Owen Duffy wrote in news:Xns9D9A202A37637nonenowhere@
61.9.191.5:

Owen Duffy wrote in
:

...
Miguel, I gave an expression for power in your simple source circuit
in a recent post, did you see it. Well here it is again:

Prs=(Vs/2-Vr)^2/Rs where Vs is the o/c source voltage, Vr is the
complex reflected wave voltage equivalent, Rs is the source
resistance.

If the reflected wave was always, and entirely dissipated in Rs in
that type of source, then Prs=Vr^2/Zo=Vr^2/Rs... but it isn't, see the
above expression.


Thinking about this some more, the last paragraph should say:

If the reflected wave was always, and entirely dissipated in Rs in that
type of source, then Prs=a+Vr^2/Zo=a+Vr^2/Rs (where a is some constant
value)... but it isn't, see the above expression.


To deal properly with the fact that Vr has magnitude and phase, the above
should we written as:

Prs=|(Vs/2-Vr)|^2/Rs where Vs is the o/c source voltage, Vr is the
complex reflected wave voltage equivalent, Rs is the source resistance.

If the reflected wave was always, and entirely dissipated in Rs in that
type of source, then Prs=a+|Vr|^2/Zo=a+|Vr|^2/Rs (where a is some
constant value)... but it isn't, see the above expression.

Owen