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#1
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There's a good fight brewing in QEX magazine land. Eric, K8LV, wrote a
pretty good article on directional wattmeters. But he spent a lot of space asserting that the notion of forward and reflected power in a transmission line is merely for intuitive convenience, isn't real, and should be abandoned in favor of unidirectional power flow and lumped analysis at a single point. Whoo Hoo. The letters will be fun. Especially if Eric attempts to extend his assertion to a case not-as-special, such as not-steady-state or a point in 3D space. Too bad it wasn't here. Bet we'd get a couple dozen posts before the weekend's out. Anyone want to take Eric's side? 73, Glenn AC7ZN |
#3
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Cecil Moore wrote:
Over the years, I have challenged anyone on this newsgroup to create a standing wave in a single source system without having the existence of a forward wave and a reflected wave. Nobody has furnished any proof that standing waves are possible in a single source system without the existence of forward and reflected waves. Cecil, Why would anyone try to prove that the basic math of adding sinusoidal functions is incorrect? To the contrary, you are the one who insists that a standing wave and its constituent traveling wave components are somehow different and unique. No one denies the simultaneous existence of standing waves and traveling waves. Isn't superposition wonderful! 73, Gene W4SZ |
#4
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Gene Fuller wrote:
Why would anyone try to prove that the basic math of adding sinusoidal functions is incorrect? To the contrary, you are the one who insists that a standing wave and its constituent traveling wave components are somehow different and unique. Actually, it was you who made that assertion and thanks for the opportunity to quote you once again: Gene Fuller, W4SZ wrote: In a standing wave antenna problem, such as the one you describe, there is no remaining phase information. Any specific phase characteristics of the traveling waves died out when the startup transients died out. So standing waves are "somehow different" from traveling waves according to your own assertions. The traveling wave possesses phase characteristics and the standing wave doesn't. Phase is gone. Kaput. Vanished. Cannot be recovered. Never to be seen again. So it was you who asserted that standing wave current is "somehow different" from traveling wave current and I agree with you. It's obvious they are "somehow different" because they have different mathematical equations. Have you changed your mind since your above quoted posting? No one denies the simultaneous existence of standing waves and traveling waves. Of course they do, Gene, that is the whole point. Here is a quote from K8LV's article: "I wish to emphasize the fact that the forward and reverse waves really do not exist separately ..." That certainly *denies* the separate existence of the underlying traveling waves so your above assertion is false. I believe that W7EL also denies the separate existence of forward and reverse waves and introduced the technical term, "sloshing", to explain what happens to the energy in a transmission line with reflections. -- 73, Cecil http://www.qsl.net/w5dxp |
#5
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Cecil wrote:
This is just one more example of the dumbing down of amateur radio accompanying the dumbing down of the US educational system in general. Unfortunately, it seems to be a trend that cannot be reversed because it is the biased view being pushed by the ARRL and its supporters. Hmmm...not sure I agree that the folks at ARRL are deliberately being dumb (or maybe I just misunderstood you). Seems more unintentional to me. After all, the technical editor of QEX let publish that bizarre article that claimed to prove by math that phasing SSB receivers were not possible. Can''t imagine a political motivation for that though I have to wonder bigtime how that one got by. QEX really really needs for some good peer review. Ah, to have Ham Radio magazine back again. Loved that thing. Learned most of my radio from it. 73, Glenn AC7ZN |
#6
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![]() wrote in message oups.com... Cecil wrote: This is just one more example of the dumbing down of amateur radio accompanying the dumbing down of the US educational system in general. Unfortunately, it seems to be a trend that cannot be reversed because it is the biased view being pushed by the ARRL and its supporters. Hmmm...not sure I agree that the folks at ARRL are deliberately being dumb (or maybe I just misunderstood you). Seems more unintentional to me. After all, the technical editor of QEX let publish that bizarre article that claimed to prove by math that phasing SSB receivers were not possible. Can''t imagine a political motivation for that though I have to wonder bigtime how that one got by. QEX really really needs for some good peer review. I don't think anyone is trying to be "deliberately being dumb", more like "naturally being dumb" and not knowing it. :-) Reality is that quality of technical material in ham publications is slipping, heading for stuck on stupid. Add cheapening of ham ticket exams, push for mass and no exam recruiting of new hams (a la CB wizards) in effort to boost numbers and few bad apples with it - you get the picture of deteriorating standards. When W8JI had a presentation at Dayton's Antenna Forum and spoke about his "famous - same current along the antenna loading coil", I came to K3LR (forum leader) and N6BV (ARRL Antenna Book editor) and pointed out that perhaps there is an error in W8JI assertions, I got this in private mail from the "guru": "When you pull people aside at Dayton to bitch about me or others or make wild crazy statements it just makes you look worse and worse to the people you are trying most to impress. At Dayton two years ago several people came up and told me your tried to start conversations about me with them, or that you started bitching about me." Sooo, looks like one has to take some articles in ARRL publications with biiiig grain of salt. Goofy stuff gets through, real expert material gets swept under by "know-it-alls" in charge, Goofy is right and Right is not important anymore. "Gurus" beat their drums into the publications and great confusion ensues. As far as SWR, I always tried to avoid it by matching, designing antennas to have impedance of the feedline, and the TX/Amp output matching the feedline impedance. Standing Wave Ratio always implied two waves - forward and reflected and their superposition. Why waste power in "confused" standing waves, when I can make sure that the waves are marching forward towards the antenna and be radiated. Let the waves stand in the antenna, where they belong, doing radiating and not in the lossy feedline. High SWR is not imaginary, it is real, can create excessive voltages, dielectric losses and melt the coax. Happy Mother's Day to all the mothers that did not abort us! God Bless them and thank you! Yuri, da BUm |
#7
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Yuri Blanarovich wrote:
When W8JI had a presentation at Dayton's Antenna Forum and spoke about his "famous - same current along the antenna loading coil", ... It is unusual for W8JI to give up on an argument so abruptly. I wish I had thought of the dual-Z0 shortened stub concept years ago. -- 73, Cecil http://www.qsl.net/w5dxp |
#8
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wrote:
Hmmm...not sure I agree that the folks at ARRL are deliberately being dumb (or maybe I just misunderstood you). Let me just relate my personal experience. I submitted an article to QEX which mentioned light wave theory as explained in "Optics", by Hecht. An (un-named) QEX employee, with whom I was dealing, had "Optics" as a college textbook and was very interested in the subject. He suggested that I expand the light wave theory section of my article, which I did. After about four revisions, he suddenly stopped responding to my emails. A couple of months later, I received a rejection letter. That was well over a year ago. Two QEX articles have recently appeared covering exactly the same material as my article but with different slants. QEX still will not answer my emails and will not publish my letters to the editor. My treatment by QEX is more akin to religious shunning than anything else. I am convinced that the QEX employee that I was dealing with is deliberately publishing dumbed-down material because he previously indicated that he knows different from his college optics course. He is most probably being directed to do so by his superiors because he was, at first, enthusiastic about publishing my article which is available from my web page below. -- 73, Cecil http://www.qsl.net/w5dxp/energy.htm |
#9
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Cecil Moore wrote:
Gene Fuller wrote: Why would anyone try to prove that the basic math of adding sinusoidal functions is incorrect? To the contrary, you are the one who insists that a standing wave and its constituent traveling wave components are somehow different and unique. Actually, it was you who made that assertion and thanks for the opportunity to quote you once again: Gene Fuller, W4SZ wrote: In a standing wave antenna problem, such as the one you describe, there is no remaining phase information. Any specific phase characteristics of the traveling waves died out when the startup transients died out. So standing waves are "somehow different" from traveling waves according to your own assertions. The traveling wave possesses phase characteristics and the standing wave doesn't. Cecil, You keep making the same mistake. Yes, you can analyze traveling waves instead of standing waves if you so choose. However, there is not one bit of additional physical information in the traveling waves that is not in the standing wave. Any "phase characteristic" is simply a function of the mathematical manipulations you use. Perhaps someday you will actually understand superposition, but I won't hold my breath. 73, Gene W4SZ |
#10
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Gene Fuller wrote:
However, there is not one bit of additional physical information in the traveling waves that is not in the standing wave. I agree with you but W8JI and W7EL have rejected the concept that there is any phase information in the standing wave current magnitude. They have rejected any use of the arc-cosine function in calculating that phase. The following graphs show the difference in the standing wave current and the traveling wave current. http://www.qsl.net/w5dxp/travstnd.GIF The standing wave current phase contains zero phase information as you have stated. As you say, all the standing wave current phase information is contained in the magnitude but the arc-cosine function for obtaining that phase information has been rejected by the experts. For the traveling wave, there is phase information contained in the phase, none in the magnitude. Every time you make a technical assertion, you support my argument. Seems your argument is really with the side that rejects the arc- cosine function for obtaining phase information. -- 73, Cecil http://www.qsl.net/w5dxp |
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