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Richard Harrison wrote:
Keith wrote: "Yes, indeed. But there is no power." Actually I wrote much more than that and the stuff which preceded was much more important. Keith`s perception is flawed. He is addressing r-f with a d-c mindset. R-F power flow does not stop at an SWR zero-voltage point. Like "Old Man River" it just keeps rolling along. P(t) = V(t) * I(t) is much more general than DC or sinusoidal RF. It works for any signal shape you choose, even non-repetitive ones. It certainly works for my electic company who integrate P(t) and regularly send me a bill. The zero-voltage point exists because the phase relationship between two oppositely traveling waves is fixed, and the zero-volts point is where the vectors cancel. You must simultaneously sense both waves to find a zero. Sensing either wave alone finds no dip in voltage. Carramba! From this response it is clear that you are not yet in group b). But is it: group a) P(t) is not always equal to V(t) * I(t); or group c) energy can flow when P(t) is a constant 0 ? Or maybe my list is incomplete and there is a 4th option which I missed. May I respectfully suggest that if you are having difficulty selecting which option applies to your thinking (and yet can't produce a fourth option), that you try to discover the source of your discomfort. From there, enlightenment may arise. For myself, I recognized the "double think" and so rejected c). P(t) = V(t) * I(t) seemed so fundamental that it had to be accepted thus I was forced to reject a). This left only b). Although it rejects some of the often stated and accepted explanations about transmission lines, it was the lesser of the evils. Some thinking revealed the weaknesses in the 'often stated and accepted' explanations and now all is consistent. This process took some time, prompted and assisted by the never ending arguments which go on in this group. So I do thank those mis-guided souls who argue endlessly and the patient answerers who respond mostly for the benefit of the lurker. But be that as it may, do try and figure out whether option a), b) or c) best describes your thinking. Only an increased understanding can arise. ....Keith |
Richard Harrison wrote:
Keith wrote: "Yes, indeed. But there is no power." Keith`s perception is flawed. He is addressing r-f with a d-c mindset. R-F power flow does not stop at an SWR zero-voltage point. Like "Old Man River" it just keeps rolling along. The zero-voltage point exists because the phase relationship between two oppositely traveling waves is fixed, and the zero-volts point is where the vectors cancel. Using Keith's "logic", he would also be forced to assert that in a bright ring-dark ring light interference pattern, the energy in the bright rings is trapped between the dark rings and just sits there and circulates. That's one reason why the field of optics is so far ahead of RF transmission lines. Everyone in optics understands interference patterns which is exactly what RF standing waves are. -- 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! =----- |
On Wed, 20 Aug 2003 11:36:57 -0500, W5DXP
wrote: That's one reason why the field of optics is so far ahead of RF transmission lines. Everyone in optics understands interference patterns which is exactly what RF standing waves are. Hi Cecil, And you have yet to confirm it (or refute it) at the bench. Is your interest more rhetorical than actual? We engaged in a rather lengthy interchange to this topic, up to the point of how you could evidence this for yourself. My methods and data support your statement's sense. I offered only one proviso of your rig being able to withstand the demands of such mismatch and you offered your SGC could do that easily. As is stands left at that, the remaining task should occupy no more than 10 Minutes of 16 readings and note taking. 73's Richard Clark, KB7QHC |
W5DXP wrote:
wrote: In reality there is not zero volts in the incident wave or in the reflected wave. There`s full voltage coming and going. The volts just happen to be out-of-phase at this point. Yes, indeed. But there is no power. Power is the same as irradiance in optics. When total V=0, it is simply the result of destructive interference. Perhaps this quote from _Optics_, by Hecht, will enlighten you. "The principle of conservation of energy makes it clear that if there is constructive interference at one point, the "extra" energy at that location must have come from elsewhere. There must therefore be destructive interference somewhere else." My knowledge of optics is insufficient to comment on any analogies you choose to draw. Fortunately, a knowledge of optics is unnecessary to understand circuits and transmission lines. The voltage goes to zero because two voltage waves are engaged in destructive interference. The current goes to maximum because two current waves are engaged in constructive interference. The momentum in the voltage waves simply transfers to the current waves and they just keep on rolling along. There is no mechanism of physics existing at that point to change the momentum of the waves. Believing that no energy crosses a superposed V=0 boundary is just a wet dream. This puts you in group a) P(t) is not always equal to V(t) * I(t); or group c) "double think". Care to think about which and comment? The current is at an absolute maximum point so plenty of charge carriers are crossing that boundary. Yes indeed, but current by itself is not energy. Remember P(t) = V(t) * I(t) [unless you choose option a)] Both volts and amps are simultaneously necessary for power. ....Keith |
W5DXP wrote:
It happens all the time in optics and no optics engineer would be silly enough to assert that the bright ring energy is trapped and circulating between the dark rings. Nor would he be silly enough to assert that energy first goes to the dark ring and then turns around and goes to bright ring. ac6xg |
Richard Clark wrote:
W5DXP wrote: That's one reason why the field of optics is so far ahead of RF transmission lines. Everyone in optics understands interference patterns which is exactly what RF standing waves are. And you have yet to confirm it (or refute it) at the bench. Is your interest more rhetorical than actual? Actually, I confirmed it in my back yard some 15 years ago. It wasn't rocket science. -- 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! =----- |
wrote:
My knowledge of optics is insufficient to comment on any analogies you choose to draw. Fortunately, a knowledge of optics is unnecessary to understand ... transmission lines. Equally unfortunately, that's just a delusion of yours. Care to think about which and comment? I have no idea what you are talking about. Yes indeed, but current by itself is not energy. Hmmmmm, I^2*Z0 is not power? (Somebody get the net). -- 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! =----- |
On Wed, 20 Aug 2003 18:25:17 -0500, W5DXP
wrote: Richard Clark wrote: W5DXP wrote: That's one reason why the field of optics is so far ahead of RF transmission lines. Everyone in optics understands interference patterns which is exactly what RF standing waves are. And you have yet to confirm it (or refute it) at the bench. Is your interest more rhetorical than actual? Actually, I confirmed it in my back yard some 15 years ago. It wasn't rocket science. Hi Cecil, I see you haven't got a clue what I wrote. Never mind. 73's Richard Clark, KB7QHC |
Richard Clark wrote:
W5DXP wrote: Richard Clark wrote: And you have yet to confirm it (or refute it) at the bench. Is your interest more rhetorical than actual? Actually, I confirmed it in my back yard some 15 years ago. It wasn't rocket science. I see you haven't got a clue what I wrote. Never mind. On the contrary, my bench was located in my back yard in Queen Creek, AZ at the time - during the dry season, of course. -- 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! =----- |
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