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#1
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Steve Nosko wrote:
100W XMTR---50 ohm coax---x---1/2 WL 450 ohm ladder-line---50 ohm load Assuming yes... I think you are saying that we have a 450 ohm line and a 50 ohm load and therefore there is a reflection. Is that where you are? Yes, there are reflections on the 450 ohm ladder line and none on the 50 ohm coax. There is no reflected energy on the 50 ohm coax and therefore no momentum in the reflected waves on the 50 ohm coax. I think you contradicted yourself here. Are you saying that there IS or IS NOT reflected energy/waves on the 50 ohm section (to the left of the "--x--"?? No contradiction. There's no reflected energy on the 50 ohm coax because those two reflections are cancelled at the Z0-match point 'x'. They are equal in magnitude and opposite in phase. So what changes the direction and momentum of the energy wave reflected from the load? You lost me here. Perhaps you are asking; "If there is a wave reflected at the end with the 50 ohm, back toward the left, how does this power then get absorbed IN that load?" Is this the question? No, there is 178 joules/sec rejected by the load on the 450 ohm line. That energy possesses direction and momentum toward the source. What reverses the direction and momentum of that reflected energy? The wave, in the 450 section, reflected from the load is NOT the power being delivered TO the load, so it does not have to be "changed' to be delivered there. There is 100 joules/sec traveling to the right and none to the left on the 50 ohm coax. There is 278 joules/sec traveling to the right and 178 joules/sec to the left on the 450 ohm ladder-line. How does the rearward traveling 178 joules/sec, rejected by the load, get turned around and join the forward traveling 100 source joules/sec in order to add up to 278 joules/sec of forward power on the ladder line that is incident upon the load? It's a simple question: How does energy rejected by the load become energy incident upon the load? -- 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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#2
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Interesting question and actually BEFORE I read R. Clark's post I decided to say that I will begg off at this point. I may be overcome with curiosity on this question in the near future (like I did for the QST WATTMETER article calculations), but for now I prefer not to take the challenge. Joules are much more than I want to consider. Job, Wife, Mother, Mother-in-law, sister-in-law all needing care and a job that is full of crap. I use this for enjoyable discussions that I can contribute to and this a way more brain power that I want to devote. I suspect you, Cecil, can explain it. I know that a 1/2 wave repeats the load Z, smith Chart and all that and can work with that. you win. 73 -- Steve N, K,9;d, c. i My email has no u's. "Cecil Moore" wrote in message ... Steve Nosko wrote: 100W XMTR---50 ohm coax---x---1/2 WL 450 ohm ladder-line---50 ohm load Assuming yes... I think you are saying that we have a 450 ohm line and a 50 ohm load and therefore there is a reflection. Is that where you are? Yes, there are reflections on the 450 ohm ladder line and none on the 50 ohm coax. There is no reflected energy on the 50 ohm coax and therefore no momentum in the reflected waves on the 50 ohm coax. I think you contradicted yourself here. Are you saying that there IS or IS NOT reflected energy/waves on the 50 ohm section (to the left of the "--x--"?? No contradiction. There's no reflected energy on the 50 ohm coax because those two reflections are cancelled at the Z0-match point 'x'. They are equal in magnitude and opposite in phase. So what changes the direction and momentum of the energy wave reflected from the load? You lost me here. Perhaps you are asking; "If there is a wave reflected at the end with the 50 ohm, back toward the left, how does this power then get absorbed IN that load?" Is this the question? No, there is 178 joules/sec rejected by the load on the 450 ohm line. That energy possesses direction and momentum toward the source. What reverses the direction and momentum of that reflected energy? The wave, in the 450 section, reflected from the load is NOT the power being delivered TO the load, so it does not have to be "changed' to be delivered there. There is 100 joules/sec traveling to the right and none to the left on the 50 ohm coax. There is 278 joules/sec traveling to the right and 178 joules/sec to the left on the 450 ohm ladder-line. How does the rearward traveling 178 joules/sec, rejected by the load, get turned around and join the forward traveling 100 source joules/sec in order to add up to 278 joules/sec of forward power on the ladder line that is incident upon the load? It's a simple question: How does energy rejected by the load become energy incident upon the load? -- 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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#3
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Steve Nosko wrote:
you win. 73 It's not a contest, Steve, it is a search for the truth. I thought maybe you could offer something compelling. The following two questions are very similar: 1. How does RF power (joules/sec) rejected by the load wind up being incident upon that same load some time later in a Z0-matched system? 2. How does irradiance (joules/sec) rejected by a pane of glass wind up being incident upon that same glass pane some time later in a non- glare air/thin-film/glass system? Question #2 was answered decades ago by optics physicists. Question #1 still remains unanswered by RF physicists and engineers even though it has virtually the same answer as Question #2. -- 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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#4
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Cecil,
With reference to question #2: Who says such a silly thing? Not Melles-Griot, who appear to be your favorite optical reference source. Not Born and Wolf in "Principles of Optics", which is the ultimate optics reference book. Not any professional optics experts I have ever encountered. If you go ahead and solve the antireflective glass problem using standard Maxwell's equations (sorry, Reg and Peter) with standard boundary conditions for E and H fields you will find there is not the slightest bit of confusion. This analysis is shown in many optics and E&M textbooks. In the perfectly antireflective case all of the waves keep moving in the same direction, from air to thin film to glass. If one postulates the existence of a wave in the reverse direction it will be discovered that the amplitude of that wave is zero, meaning it does not exist. There is no "bouncing back and forth" of confused energy not knowing where and how to turn around. The interference model is useful and intuitive for what it is meant to explain. However, don't expect this sort of simple handwaving model to be extendable to all sorts of silliness about energy and momentum transfer. 73, Gene W4SZ Cecil Moore wrote: Steve Nosko wrote: you win. 73 It's not a contest, Steve, it is a search for the truth. I thought maybe you could offer something compelling. The following two questions are very similar: 1. How does RF power (joules/sec) rejected by the load wind up being incident upon that same load some time later in a Z0-matched system? 2. How does irradiance (joules/sec) rejected by a pane of glass wind up being incident upon that same glass pane some time later in a non- glare air/thin-film/glass system? Question #2 was answered decades ago by optics physicists. Question #1 still remains unanswered by RF physicists and engineers even though it has virtually the same answer as Question #2. |
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#5
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On Wed, 10 Mar 2004 19:53:20 GMT, Gene Fuller
wrote: However, don't expect this sort of simple handwaving model to be extendable to all sorts of silliness about energy and momentum transfer. It all goes to the measure of Standard handWaving Ridiculousness. |
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#6
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Gene Fuller wrote:
In the perfectly antireflective case all of the waves keep moving in the same direction, from air to thin film to glass. To prove that to be a true statement you must prove that the transistion point between materials of different indices of refraction results in zero reflections. Good luck on that one. For instance, one can change the thin-film thickness from 1/4WL to 1/2WL and cause exactly the opposite effect, i.e. extreme glare. If you are using the quantum electrodynamics model, please let us know. Most of the rest of us are using the EM wave reflection model. -- 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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#7
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Cecil,
I haven't the foggiest idea what model you might be using. I am using the classical model that is found in virtually any textbook that deals with plane waves in non-conducting media. I don't have to "prove" anything. Just set up the standard wave equations with the standard boundary conditions and the problem practically solves itself. The non-zero remaining waves are all moving in the same direction. I forgot to ask them if they realize that Cecil doesn't approve of such behavior. I suppose this is an prime example of being seduced by "math models", but I believe that is a lesser fault than being seduced by Cecil's imaginary models. 73, Gene W4SZ Cecil Moore wrote: Gene Fuller wrote: In the perfectly antireflective case all of the waves keep moving in the same direction, from air to thin film to glass. To prove that to be a true statement you must prove that the transistion point between materials of different indices of refraction results in zero reflections. Good luck on that one. For instance, one can change the thin-film thickness from 1/4WL to 1/2WL and cause exactly the opposite effect, i.e. extreme glare. If you are using the quantum electrodynamics model, please let us know. Most of the rest of us are using the EM wave reflection model. |
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#8
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Gene Fuller wrote:
I don't have to "prove" anything. Just set up the standard wave equations with the standard boundary conditions and the problem practically solves itself. The non-zero remaining waves are all moving in the same direction. I forgot to ask them if they realize that Cecil doesn't approve of such behavior. You should have warned us that you were talking about NET waves and NET energy transfer. I'm not discussing that at all. I am talking about component waves and component energy transfer without which standing waves cannot exist. Or maybe you can offer an example of standing waves in the absence of at least two waves traveling in opposite directions. If you can do that, I will admit defeat. I suppose this is an prime example of being seduced by "math models", but I believe that is a lesser fault than being seduced by Cecil's imaginary models. It is indeed an example of being seduced by the NET math model. Please transfer over to the component math model and rejoin the discussion. Lots of interesting things are happening below the threshold of the NET math model. The NET math model doesn't explain anything except the NET results. If your bank account balance doesn't change from one month to another, do you also assume that you have written no checks and have no income for that month? Literally speaking, please get real! -- 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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#9
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Gene Fuller wrote:
In the perfectly antireflective case all of the waves keep moving in the same direction, from air to thin film to glass. I just realized what you are saying. Your above statement is wrong about "all of the waves". Your above statement is correct about "net irradiance". I'm not talking about "net" anything. I am talking about the component forward and reflected waves which are easily proven to exist. -- 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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