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Dan wrote:
Now that the various typo mistakes have been corrected, and putting aside for the moment the name calling and ad hominem arguments, could it be that _both_ sides in this discussion are correct? Camp 'A' says that the reflection coefficient is computed the classical way, without using Zo conjugate, and offers various mathematical proofs and discussions of infinitely long lines. Camp 'B' says the reflection coefficient is computed with Zo* (Zo conjugate) in the numerator, and offers explanations dealing with the conservation of energy and maximum transfer of power. No one from "Camp B" has given any justification for the assumption that the condition for minimum reflection is the condition for maximum power transfer. We're lacking either a proof, a derivation from known principles, or even a numerical example. I maintain that this assumption is false. Likewise, there's no evidence that the conventional and universally accepted (within the professional community) formula for reflection coefficient violates the conservation of energy. If it did, it would have been shown to be in error long ago. Both sides may be correct since they are talking about _two different_ meanings for the term "reflection coefficient." One has to do with voltage (or current) traveling waves and the other has to do with power. . . Perhaps. Yet both groups have used it as though it's a voltage reflection coefficient, and as justification for statements made about the reflection of voltage waves. If people want to argue about the reflection of power waves, I'll gladly bow out and let Cecil and his colleagues resume their interminable arguments without me. If anyone wants to discuss voltage or current waves, I'll try to continue to contribute, as long I don't have to deal with Slick and the insults he uses in place of supporting evidence. . . . So, it seems to me, everybody can agree as long as it is understood that there are different meanings for the term "reflection coefficient." One meaning, and its mathematical definition, applies to voltage or current waves. The other, with a slightly different mathematical definition, applies to the power transfer from a line to a load. They are one and the same only when the reactive portion of Zo (Xo) is ignored. It may or may not be acceptable to do so, depending on the attenuation of the line and the frequency. Lossy lines and lower frequencies yield more negative values for the Xo component of Zo. I suggest that those who are using "reflection coefficient" as meaning the ratio of reflected to forward power so state, and restrict their conclusions dervived from it to power waves. . . . Roy Lewallen, W7EL |