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#81




Dr. Slick wrote:
Cecil, email me privately and i will send you the paper. He calls the voltage reflection coefficient the "power wave reflection coefficient". And then squares this to get the "power reflection coefficient". It's really a bad nomenclature, and no wonder there is confusion. I agree, it is bad nomenclature. He should have called it the amplitude or voltage reflection coefficient, the square of which is the power reflection coefficient.  73, Cecil http://www.qsl.net/w5dxp = Posted via Newsfeeds.Com, Uncensored Usenet News = http://www.newsfeeds.com  The #1 Newsgroup Service in the World! == Over 100,000 Newsgroups  19 Different Servers! = 
#82




"Dr. Slick" wrote in message om... "David Robbins" wrote in message ... "Dr. Slick" wrote in message om... [s]**2 = [(ZL  Zo*) / (ZL + Zo)]**2 the "power reflection coefficent". Note the squares. yes, please do note the squares.... and remember, just because [s]**2 = [(ZL  Zo*) / (ZL + Zo)]**2 does NOT mean that s = (ZL  Zo*) / (ZL + Zo) this is the one big trap that all you guys that like to use power in your calculations fall into. just because you know the power doesn't mean that you know squat about the voltage and current on the line. you can not work backwards. that is why it is always better to work with voltage or current waves and then in the end after you have solved all those waves you can always calculate power if you really need to know it. yes, but he does say that s = (ZL  Zo*) / (ZL + Zo) , first. But he foolishly calls it a "power wave R. C." Then he squares the magnitudes [s]**2 = [(ZL  Zo*) / (ZL + Zo)]**2 And calls this the "power R. C." The bottom label is fine, we've all see this before, as the ratio of the RMS incident and reflected voltages, when squared, should give you the ratio of the average incident and reflected powers, or the power R. C. But to call the voltage reflection coefficient a "power wave R. C." is really foolish, IMO. Slick i don't know what he is refering to as the 'power wave rc' but its not the voltage or current reflection coefficient, they do not have a conjugate in the numerator. 
#83




Richard,
Thanks. *Really* sharp guy. Must be 90 years old by now. Tam/WB2TT "Richard Clark" wrote in message ... On Sun, 24 Aug 2003 12:57:36 0400, "Tarmo Tammaru" wrote: "Richard Clark" wrote in message .. . Chipman also discusses the relevancy of the characteristic Z of a source to SWR, which is tucked away in the unread part. ;) 73's Richard Clark, KB7QHC Richard, There used to be a Dr. Chipman who taught a fields/waves course at the University of Toledo (OH) in the 60s. Do you know if it is the same guy? Tam/WB2TT Hi Tam, According to the front cover, one in the same. 73's Richard Clark, KB7QHC 
#84




David Robbins wrote:
i don't know what he is refering to as the 'power wave rc' but its not the voltage or current reflection coefficient, they do not have a conjugate in the numerator. And since the power reflection coefficient (Reflectance) is simply the square of the voltage (amplitude) reflection coefficient, presumably neither would it. There is no conjugate in these equations in the field of optics.  73, Cecil http://www.qsl.net/w5dxp = Posted via Newsfeeds.Com, Uncensored Usenet News = http://www.newsfeeds.com  The #1 Newsgroup Service in the World! == Over 100,000 Newsgroups  19 Different Servers! = 
#86




"David Robbins" wrote in message ...
i don't know what he is refering to as the 'power wave rc' but its not the voltage or current reflection coefficient, they do not have a conjugate in the numerator. Incorrect. You need the conjugate in the numerator if the Zo is complex. If it is purely real, WHICH MOST TEXTS ASSUME, then you can use the normal equation. Look he http://www.zzmatch.com/lcn.html And look up Les Besser's notes on the Fundamentals of RF. Slick 
#87




W5DXP wrote in message ...
Dr. Slick wrote: Cecil, email me privately and i will send you the paper. He calls the voltage reflection coefficient the "power wave reflection coefficient". And then squares this to get the "power reflection coefficient". It's really a bad nomenclature, and no wonder there is confusion. I agree, it is bad nomenclature. He should have called it the amplitude or voltage reflection coefficient, the square of which is the power reflection coefficient. Agreed. I will send you the paper. Slick 
#88





#89




"Dr. Slick" wrote in message om... "David Robbins" wrote in message ... i don't know what he is refering to as the 'power wave rc' but its not the voltage or current reflection coefficient, they do not have a conjugate in the numerator. Incorrect. You need the conjugate in the numerator if the Zo is complex. If it is purely real, WHICH MOST TEXTS ASSUME, then you can use the normal equation. sorry, the derivation for the table in the book i sent before is for the general case of a complex Zo. they then go on to simplify for an ideal line and for a nearly ideal line... nowhere does a conjugate show up. and that reference you give is not for a load on a transmission line, it is talking about a generator supplying power to a load... a completely different animal. 
#90




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 
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