The power explanation
Jim - NN7K wrote in news:C2LFh.5953$re4.1319
@newssvr12.news.prodigy.net:
And, in fact, the "Reflected power" is
"Re-reflected" from the Source, Back to
the Load, if memory serves (minus loss's
accumulated from the first "Reflection"
of power, if memory serves! Jim NN7K
All this consideration of re-reflected, re-re-reflected, re-re-re-re-
reflected energy is something that is appropriate to analysing how the
steady state is established, and yes I know it takes an infinite time,
but it establishes subtantially quite quickly. The transient converges to
the steady state.
To find the steady state solution, take a short cut, bypass the transient
analysis and jump straight to the converged situation. In the steady
state... The complex ratio of Vf to Vr at the load end is entirely
determined by the constraints of a transmission line of Zo and the
passive load. The complex ratio of Vf to Vr at the line input can be
determined from the load end conditions by applying the line transmission
formulas with the complex propagation constant. Knowing Vf and Vr at the
input of the line and Zo, the complex V/I ratio (the equivalent load)
that the loaded line input will enforce can be calculated. The power
delivered by the source can be then found by finding the voltage or
current it will supply into the equivalent load.
This might seem long winded, but it is a sight easier than solving some
thousands of iterations of reflection, re-reflection and so on.
Owen
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