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#161
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Where does it go? (mismatched power)
On 18 jun, 07:55, K1TTT wrote:
On Jun 17, 10:55*pm, Cecil Moore wrote: On Jun 17, 5:08*pm, K1TTT wrote: but you have already admitted that it is the only mechanism... though you will now undoubtedly argue against yourself. * em wave reflection IS the only mechanism for redistributing rf energy, you admitted that when you agreed that superposition of the waves is the mechanism that causes the interference in the first place. Superposition and reflection are NOT the same mechanism. You are i didn't say they were totally confused about what I have said. Wave REFLECTION (of one wave) is not caused by SUPERPOSITION (of two waves) and vice versa. Wave reflection happens to a single wave when it encounters an impedance discontinuity. Superposition requires two or more waves. They are clearly two completely different mechanisms. So I will repeat what I said befo There are two mechanisms for redistributing the reflected energy back toward the load. 1. The re-reflection of the SINGLE reflected wave from the load at an impedance discontinuity associated with the power reflection its really the voltage and current reflection coefficient. coefficient, e.g. 0.5 in my earlier example. Thus in that earlier example, 1/2 of the reflected energy from the load is re-reflected back toward the load and joins the forward wave toward the load. That leaves 1/2 of the reflected energy that is transmitted through the impedance discontinuity toward the source without being reflected. The second energy redistribution mechanism occurs associated with superposition of MULTIPLE WAVES. that is what i said, and what you agreed to earlier. 2. The percentage of the reflected energy from the load that is transmitted through the impedance discontinuity toward the source superposes with the reflection of the source forward wave from the impedance discontinuity. In my earlier example, the following two wavefronts superpose in the direction of the source. Pfor1(rho^2) = 50w and Pref2(1-rho^2) = 50w Pref1 = 50w + 50w - 2*SQRT(50w*50w) = 0 This is the second mechanism (wave cancellation) that redistributes but that is NOT a "second' mechanism. *it IS superposition, which is what you agreed to earlier, maybe in a different thread. *the mechanism is superposition, the observation is that the waves interfere either constructively or destructively. the energy in the canceled wavefronts back toward the load. This step 2 is technically NOT a reflection since it involves two waves. This is the step that the RF gurus are missing. no we are not, we understand superposition which is the underlying basic mechanism of your optical interference terms. I really wish you understood the s-parameter equations which are easier to discuss than the above RF equations. In the s-parameter equation: b2 = s21*a1 + s22*a2 the term, s22*a2, is the SINGLE WAVE re-reflection term, i.e. a2 is the reflected voltage from the load. In the other s-parameter equation: b1 = s11*a1 + s12*a2 = 0 s11*a1 and s12*a2 are the TWO WAVEFRONTS that superpose to zero, i.e. stop there and you are perfectly correct. engage in wave cancellation. -- 73, Cecil, w5dxp.com- Ocultar texto de la cita - - Mostrar texto de la cita -- Ocultar texto de la cita - - Mostrar texto de la cita - the mechanism is superposition, the observation is that the waves interfere either constructively or destructively. In the end you will see you basically agree and 90% of this issue it is the Babel curse :) |
#162
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Where does it go? (mismatched power)
On Jun 18, 5:55*am, K1TTT wrote:
1. The re-reflection of the SINGLE reflected wave from the load at an impedance discontinuity associated with the power reflection its really the voltage and current reflection coefficient. It's really an electromagnetic wave obeying all the laws of physics for an electromagnetic wave INCLUDING ENERGY CONTENT. ExH is the power density of the wave and the voltage coefficient squared is the power reflection coefficient. All of the power/energy math used on a Z0- match gives identical answers as using the voltages PLUS it answers the original question asked by the first poster to this thread about what happens to reflected energy. The answer is that reflected energy, like any other energy, is conserved traveling at the speed of light in the medium, until it is dissipated or radiated. Try measuring the voltage and current content of a laser beam and you will realize why optical physicists are decades ahead of RF engineers in understanding where EM wave energy goes. This [superposition] is the second mechanism (wave cancellation) that redistributes but that is NOT a "second' mechanism. *it IS superposition, which is what you agreed to earlier, maybe in a different thread. In my statement above "This" refers to "superposition" which is the second mechanism after reflection, the first mechanism. ***I REPEAT! (1) REFLECTION IS NOT THE SAME AS (2) SUPERPOSITION!!!*** You are now just engaging in obfuscation of what I have said. I expect such shabby behavior from others on this newsgroup, but not from you. Wave cancellation is just a special case of superposition, i.e. wave cancellation is superposition. (2nd mechanism) Superposition == Interference == Wave Cancellation, which is ***NOT*** the same as (1st mechanism) Reflection. I cannot say it any plainer than that. -- 73, Cecil, w5dxp.com |
#163
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Where does it go? (mismatched power)
On Jun 18, 5:57*am, K1TTT wrote:
you edited too much out of context... it doesn't matter which method you use to calculate where it goes as long as you know the limitations of your method. Exactly! The method that most RF engineers use does not tell how the energy flows. Witness the posters who are implying that a reflected wave contains no energy because they cannot figure out where that energy goes or how it gets there. In his food-for-thought example, w7el completely ignores the role of superposition/interference in redistributing the energy, a phenomenon known and understood in the field of optical physics for at least a century. -- 73, Cecil, w5dxp.com |
#164
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Where does it go? (mismatched power)
On Jun 18, 8:43*am, lu6etj wrote:
In the end you will see you basically agree and 90% of this issue it is the Babel curse :) Don't forget the 10% of misquotes. -- 73, Cecil, w5dxp.com |
#165
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Where does it go? (mismatched power)
On Jun 18, 10:28*am, Cecil Moore wrote:
In my statement above "This" refers to "superposition" which is the second mechanism after reflection, the first mechanism. ***I REPEAT! (1) REFLECTION IS NOT THE SAME AS (2) SUPERPOSITION!!!*** You are now just engaging in obfuscation of what I have said. I expect such shabby behavior from others on this newsgroup, but not from you. NOW ITS MY TURN TO YELL! I NEVER SAID THAT REFLECTION WAS THE SAME AS SUPERPOSITION, I HAVE BEEN SAYING THAT YOUR 'WAVE CANCELLATION' AND 'INTERFERENCE' ARE SUPERPOSITION! JUST WHAT YOU ADMIT BELOW: Wave cancellation is just a special case of superposition, i.e. wave cancellation is superposition. |
#166
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Where does it go? (mismatched power)
On Jun 18, 10:35*am, Cecil Moore wrote:
On Jun 18, 5:57*am, K1TTT wrote: you edited too much out of context... it doesn't matter which method you use to calculate where it goes as long as you know the limitations of your method. Exactly! The method that most RF engineers use does not tell how the energy flows. Witness the posters who are implying that a reflected wave contains no energy because they cannot figure out where that energy goes or how it gets there. In his food-for-thought example, w7el completely ignores the role of superposition/interference in redistributing the energy, a phenomenon known and understood in the field of optical physics for at least a century. -- 73, Cecil, w5dxp.com because, at least when i do circuit design, i NEVER calculate energy, and only at the end calculate power if i really need to. voltage and current or E and H are the simpler things to handle and totally sufficient for all circuit analysis, either lumped or distributed. |
#167
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Where does it go? (mismatched power)
On Jun 18, 11:48*am, K1TTT wrote:
NOW ITS MY TURN TO YELL! *I NEVER SAID THAT REFLECTION WAS THE SAME AS SUPERPOSITION, I HAVE BEEN SAYING THAT YOUR 'WAVE CANCELLATION' AND 'INTERFERENCE' ARE SUPERPOSITION! *JUST WHAT YOU ADMIT BELOW: When I said reflection is the first mechanism and superposition is the second mechanism, you said: "... but that [referring to superposition] is NOT a "second' mechanism." The implication seemed clear to me. Good grief, everyone is free to review what I said and what you said in disagreement. I said reflection is the first mechanism and superposition is the second mechanism. You said superposition is NOT a second mechanism, clearly implying that superposition is the same as the first mechanism which was already defined by me as reflection. Your implication was clearly that reflection and superposition are the same mechanism. Do you agree that wave reflection can cause a redistribution of wave energy? Do you agree that superposition can cause a redistribution of wave energy? Do you agree that wave reflection and wave superposition are two different mechanisms? If so, you agree with everything I have previously said and are now just blowing smoke. If you misspoke, just admit it. If you misunderstood what I said, just admit it. If you have changed your mind, just admit it. If you still disagree with any of those three statements, please continue the argument that you started in response to my assertion that there exists two mechanisms that can redistribute energy in a transmission line, (1) reflection and (2) superposition. -- 73, Cecil, w5dxp.com |
#168
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Where does it go? (mismatched power)
On Jun 18, 11:51*am, K1TTT wrote:
because, at least when i do circuit design, i NEVER calculate energy, and only at the end calculate power if i really need to. *voltage and current or E and H are the simpler things to handle and totally sufficient for all circuit analysis, either lumped or distributed. The subject of this thread is "Where does it go? (mismatched power)", not "How do I do circuit design?" -- 73, Cecil, w5dxp.com |
#169
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Where does it go? (mismatched power)
On Jun 18, 5:39 pm, Cecil Moore wrote:
On Jun 18, 11:48 am, K1TTT wrote: NOW ITS MY TURN TO YELL! I NEVER SAID THAT REFLECTION WAS THE SAME AS SUPERPOSITION, I HAVE BEEN SAYING THAT YOUR 'WAVE CANCELLATION' AND 'INTERFERENCE' ARE SUPERPOSITION! JUST WHAT YOU ADMIT BELOW: When I said reflection is the first mechanism and superposition is the second mechanism, you said: "... but that [referring to superposition] is NOT a "second' mechanism." The implication seemed clear to me. Good grief, everyone is free to review what I said and what you said in disagreement. I said reflection is the first mechanism and superposition is the second mechanism. You said superposition is NOT a second mechanism, clearly implying that superposition is the same as the first mechanism which was already defined by me as reflection. Your implication was clearly that reflection and superposition are the same mechanism. Do you agree that wave reflection can cause a redistribution of wave energy? no. wave reflection causes current and voltage waves to change direction, magnitude, and phase. Do you agree that superposition can cause a redistribution of wave energy? your observed 'redistribution of wave energy' is a results of superposition of current and voltage waves and then another calculation to convert the sum to power and another calculation to integrate the energy. Do you agree that wave reflection and wave superposition are two different mechanisms? of course, i've never said otherwise. If so, you agree with everything I have previously said and are now just blowing smoke. If you misspoke, just admit it. If you misunderstood what I said, just admit it. If you have changed your mind, just admit it. If you still disagree with any of those three statements, please continue the argument that you started in response to my assertion that there exists two mechanisms that can redistribute energy in a transmission line, (1) reflection and (2) superposition. -- |
#170
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Where does it go? (mismatched power)
On Jun 18, 5:41*pm, Cecil Moore wrote:
On Jun 18, 11:51*am, K1TTT wrote: because, at least when i do circuit design, i NEVER calculate energy, and only at the end calculate power if i really need to. *voltage and current or E and H are the simpler things to handle and totally sufficient for all circuit analysis, either lumped or distributed. The subject of this thread is "Where does it go? (mismatched power)", not "How do I do circuit design?" -- 73, Cecil, w5dxp.com since when did any thread like this stay on topic for more than a couple messages? |
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