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On Thu, 1 Mar 2007 20:13:32 +0000, Ian White GM3SEK
wrote: I ordered the book from the other side of the world because I wanted to be very sure of my answers next time around. Hi Ian, It will contain much of interest. For instance, it relates to Owen's moribund thread "the power explanation." Page 205, third paragraph from the bottom conforms to one of my recent posts the "Although the power delivered by the source to the line is thus shown to be reduced by the amount of the reflected power returning to the input terminals ... the implication of the latter reasoning that the reflected wave power is entirely absorbed in the source impedance without affecting the total output of the signal source generator, is incorrect." Contrary to that teaching, is discussion on page 203, last paragraph. It relates to figure 9-26, clearly illustrating a mismatched line fed by a source with a source resistance. This may be upsetting to many: "At the signal source end of the line ... none of the power reflected by the terminal load impedance is re-reflected on returning to the input end of the line." The ellipsis reveals that the source Z matches the line Z. To begin at the beginning of multiple reflection coverage, go to the same named section (8.8) on page 174. It is not his complete say on the topic, but it starts here formally. To add insult to someone's injury, his math includes source Z. However, by the same token Chipman explicitly states: "... the shape of the standing wave pattern ... is in no way affected by the quantities Vs, Zs and Rho-s at the source." I would also note the irony in that Chipman expresses reflections in lines in terms of power. To subdue that irony, I would also admit he is quick to shift to energy when the usage of power is to lead to problematic solutions (so, using power as an expression in this context is allowable by precedent as being informal). Of course, Chipman must be accepted as an authority for any of these issues to be considered valid. 73's Richard Clark, KB7QHC |
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