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#141




"Peter O. Brackett" wrote in message link.net... Dave: The impedance matching dynamics at the reference plane/junction point are the same for distributed and lumped systems, they obey all the same equations, their electrodyanamics is the same, one simply cannot tell the difference at the driving point. If you don't like lumped models, then make the internal resistance of the Thevenin generator out of a distributed line. It will work just the same way. i'm sorry, but that just isn't true. make me an equivalent, with a distributed line, of a 1v step voltage source in series with a 1ohm resistor. 
#142




"W5DXP" wrote in message ... David Robbins wrote: these discussions always seem to end up in this same quagmire, one group trying to solve everything with wave equations, sinusoidal steady states, transmission line transformations, and the other holding on to the lumped models and trying to make them fit the wrong problem domain. Plus a third group of particle physicists saying waves don't exist. :) what is really fun is watching those guys try to explain reflections with photons getting absorbed and reemitted. 
#143




David Robbins wrote:
"W5DXP" wrote: Plus a third group of particle physicists saying waves don't exist. :) what is really fun is watching those guys try to explain reflections with photons getting absorbed and reemitted. Yep, I notice I got no answer (so far) to my question about reflected photons. And, apparently, when one electron gets too close to another, they each emit virtual photons as a warning not to come any closer.  73, Cecil, W5DXP 
#144




David:
[snip] sorry, not always... another clear generalization from oversimplifying and applying the wrong model. there are cases where there is zero reflected voltage for a conjugate match. [snip] David, my friend as I stated several times, there is only one such case NOT "cases" and occurs only when Zo is purely resistive. In that case the conjugate is nonexistent! What's your point? Wanna proof: The reflection coefficient is identically zero, rho = (Z  Zo)/(Z + Zo) = 0 If and only if the numerator of rho is identically zero. (Z  Zo) = 0 Solving for the unknown Z, this occurs whenever. Z = Zo For complex Zo = ro + jxo, conjugate match occurs whenever Z = ro  jxo and so rho can only be zero when: ro  jxo = ro + jxo which only occurs when xo = xo This can only happen if xo = 0, i.e. the reactive part of both Z and Zo are identically zero. i.e. xo = xo if and only if xo = 0 And this only occurs when Zo is real, not when it is complex! What exactly is your point?  Peter K1PO Indialantic BytheSea, FL. 
#145




Roy:
[snip] "Roy Lewallen" wrote in message ... Not QED at all. You claimed to have proved that maximum power is delivered to a load when a transmission line is terminated such that the reflected voltage on the line is zero. [snip] No I did not! Never said that, never have. Where did you get that idea? I said that for a general complex Zo the reflected voltage is generally NOT zero at maximum power transfer. To make myself perfectly clear, let me repeat that... I said that for a general complex Zo the reflected voltage is generally NOT zero at maximum power transfer. I said that for a general complex Zo the reflected voltage is generally NOT zero at maximum power transfer. I said that for a general complex Zo the reflected voltage is generally NOT zero at maximum power transfer. [snip] Here, you're agreeing that the reflected voltage is zero when the line is terminated in its characteristic impedance. So where's the proof that this condition leads to maximum power to the load? Roy Lewallen, W7EL [snip] What I was trying to prove was that the reflected voltage is NOT zero at conjugate match for the case of complex Zo! I proved that by setting up a transmission line with perfect image [not conjugate] matching on both ends [Zo is seen looking in both directions from any point in the system] and driven by a generator set up to create the incident wave. That system has no impedance discontinuities anywhere. The impedance is Zo all along the line and into the generator looking in either direction. No impedance discontinuities no reflections, period! I then calculated the classical reflection coefficient and showed it to be zero confirming that rho = 0 when there are no impedance discontinuities and the classical formula for rho is used, rho = (Z  Zo)/(Z + Zo). As the last step I changed the termination from Z0 to conj(Zo) i.e. a conjugate match, NOT an image match and showed that rho is NOT zero in this case. QED! Summarizing... Image Match: A line of surge impedance Zo terminated in Zo has no impedance discontinuities and no reflections. Conjugate Match: A line of surge impedance terminated in conj(Zo) has an impedance discontinuity and hence has reflections. [Unless in the one unique case that Zo is purely real] BTW... Aside: From the postings of Dave and yourself along this thread, I get the impression that ya'll beleive that lumped systems obey different laws and should should be modeled differently than distributed systems. I am surprised by that claim. Surely you don't mean that! Surely all electrical systems, lumped or distributed, must obey the laws of electrodynamics as set out by MaxwellHeaviside. Do you know of any cases where they don't? Regards,  Peter K1PO Indialantic BytheSea, FL. 
#146




David:
[snip] i'm sorry, but that just isn't true. make me an equivalent, with a distributed line, of a 1v step voltage source in series with a 1ohm resistor. [snip] A 1volt step voltage in series with a zero length transmission line terminated in a 1 Ohm resistor! Dave, all electrical systems, lumped and distributed alike, obey the MaxwellHeaviside equations. They are all the same, not different as you claim! Prior to Maxwell [mid 1800's] folks believed that lumped and distributed systems might obey different laws, but ever since Maxwell wrote down his celebrated 22 equations, using quaternions, and Oliver Heaviside reduced them to 4 neat little vector differential equations back in the mid 1800's, most everyone, with the apparent exception of yourself, has accepted that lumped and distributed systems obey the same laws! What exactly is your point? Do you believe that lumped systems are described by different laws than distributed systems? Are you trying to convince me of that 150 year old discredited idea? All macro  electrical systems confirm to the same laws of electrodynamics, namely the MaxwellHeaviside equations. The only systems where MaxwellHeaviside fails to predict physical reality is when dealing with the "very" small, i.e. quantum mechanics when one has to do Engineering and make predictions and design onephotonattime. In this case you have to use quantum electrodynamics or QED but still all systems, lumped or distributed must obey QED and MaxwellHeaviside is just a special case or approximation to QED laws in the aggregate when there are lots of photons. Dave you will have a lot of arguing to do to convince modern electrotechnologists that lumped systems obey different laws from distributed systems. Or that the equations of lumped impedance matching are any different from transmission line impedance matching. They are the same! The models are the same, the mathematics are the same, the experiments confirm that they are the same. Exactly what is your point?  Peter K1PO Indialantic BytheSea, FL. 
#147




Peter O. Brackett wrote:
Roy: [snip] "Roy Lewallen" wrote in message ... Not QED at all. You claimed to have proved that maximum power is delivered to a load when a transmission line is terminated such that the reflected voltage on the line is zero. [snip] No I did not! Never said that, never have. Where did you get that idea? This is from your posting of August 25:  Roy: [snip] 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. [snip] I did just that in a separate posting on this thread a couple of days ago.  Then on August 26, I posted:  . . . I'll restate something I mentioned before (first incorrectly, then corrected). Connecting a load to a transmission line which is the complex conjugate of the transmission line Z0 does *not* guarantee maximum power delivery from the source, or to the load. The load impedance which provides maximum load power is the complex conjugate of the impedance looking back from the load toward the source. That impedance is the source impedance transformed through the transmission line between source and load, and it's not generally the same as the line's Z0, or its complex conjugate. When this condition of maximum load power is met, there will almost certainly be voltage and current wave reflections on the line  there would be none only if the optimum load impedance coincidentally happened to be equal to the line Z0. So the argument that there can be no reflection of the voltage wave under the condition of maximum power transfer is wrong. You didn't show differently in your analysis, and no one has stepped forward with a contrary proof, derivation from known principles, or numerical example that shows otherwise.  To which you replied, also on August 26:  Yes I did. I guess that you missed that post.  I haven't been able to find this proof in your postings. I said that for a general complex Zo the reflected voltage is generally NOT zero at maximum power transfer. Well, shoot, I agree with that, as I always have. . . . BTW... Aside: From the postings of Dave and yourself along this thread, I get the impression that ya'll beleive that lumped systems obey different laws and should should be modeled differently than distributed systems. I am surprised by that claim. Surely you don't mean that! I believe you can build a bad or inappropriate model with lumped or distributed components, and draw invalid conclusions from them. Perhaps you missed my posting a day or two ago where I pointed out that your model using lumped components was clearly not the same as one using a transmission line, by means of the very simple test of observing the current in a load resistor. And yes, lumped systems should generally be modeled differently than distributed ones. Surely all electrical systems, lumped or distributed, must obey the laws of electrodynamics as set out by MaxwellHeaviside. Do you know of any cases where they don't? This argument of "you don't agree with my view of how things work, or my inappropriate models, therefore you don't believe in the Laws of Physics" is as tiresome as it is pompous. Roy Lewallen, W7EL 
#148




"Peter O. Brackett" wrote in message k.net... David: [snip] i'm sorry, but that just isn't true. make me an equivalent, with a distributed line, of a 1v step voltage source in series with a 1ohm resistor. [snip] A 1volt step voltage in series with a zero length transmission line terminated in a 1 Ohm resistor! sri, you cut off one important thing... your last sentence before my request... If you don't like lumped models, then make the internal resistance of the Thevenin generator out of a distributed line. It will work just the same way. i am asking you to show me a distributed model for the internal resistance of a thevenin generator that as a lumped model is a 1v step voltage source in series with a 1 ohm resistor. a zero length transmission line doesn't exist so the model is still lumped. 
#149




Roy:
[snip] This argument of "you don't agree with my view of how things work, or my inappropriate models, therefore you don't believe in the Laws of Physics" is as tiresome as it is pompous. Roy Lewallen, W7EL [snip] Sorry if I offended. I didn't mean to. And all along here I thought you were the one being tiersome and pompus! Such is the medium of news group postings. In summary, I believe that we agree completely, and that we were typing at "cross purposes". Your general accusation that no one from Camp B, what ever camp that was, seemed to show your "pique" and so I responded in kind. A waste of time, or... a lesson learned. Maxwell rules, lumped or distributive, there is no discrimination.  Peter K1PO Indialantic BytheSea, FL. 
#150




David:
[snip] i am asking you to show me a distributed model for the internal resistance of a thevenin generator that as a lumped model is a 1v step voltage source in series with a 1 ohm resistor. a zero length transmission line doesn't exist so the model is still lumped. [snip] Dave you are being picayune. No one wins a ****ing contest like this, everyone just gets **** on their hands. I could respond with... OK then... how about a transmission line of length somewhat less than exp(exp(exp1000))) meters in series with a 1 Ohm resistor. Will that do? Or do I could use a "recursive" definition. It simply doesn't address or affect the point at hand, which is that a complex Zo line terminated in its' conjugate will exhibit a nonzero reflected voltage. Do you agree? If not, what 's your point? "When I use a word", Humpty Dumpty said, in a rather scornful tone, "it means just what I choose it to mean, neither more nor less." "The question is", said Alice, "whether you can make words mean so many different things." "The question is", said Humpty Dumpty, "Who is to be master:  that's all."  Lewis Carol, "Alice in Wonderland  The Turtle soup" Dave, I am willing to help you understand my unimportant proof, I didn't realize it was such a big deal, but hey... I recall you asked or commented about my posting, but if all you wanted is to fuss with me over side issues such as if lumped systems obey different laws than distributed systems, then I presume that we will have to agree that we cannot have a productive discussion.. If I have offended you in some way, I did not mean to, please accept my appologies. Best Regards,  Peter K1PO Indialantic BytheSea, FL. 
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