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The Rest of the Story
On Mar 24, 10:46 am, Cecil Moore wrote:
Keith Dysart wrote: The energy flow into the battery is exactly and always accounted for by the energy flow that heats the battery and the energy flow consumed in the reversable chemical reaction. Point is, energy can be stored and released at a later time. You earlier said that reactances do not store energy for release at a later time yet that is exactly what reactances do. Yes indeed. And what I have said, is that when this is happening it is always possible to identify the element which is storing the energy and provide the function that describes the energy flow in and out of the element. It is this identification and function that I keep asking for to back up the handwaving claim that you have been making. A strange of way of looking at it. It seems easier just to say that there is no theta. And add the voltages. Saying there is no theta is a shortcut that can get one into trouble as it did with you. Since there is no such thing as negative energy, there is also no such thing as negative power. Bzzt. Power is the rate of change of energy. The quantity of energy can be dropping (i.e. negative power), without the quantity of energy ever going below zero. Note there are no negative power signs in the power density equation where 'theta' is the phase angle between the two interfering voltages: Ptot = P1 + P2 + 2*SQRT(P1*P2)cos(theta) Unfortunately, I took a small shortcut in my last post and left out the "(t)" from all the functions. You immediately jumped to an RMS interpretation. Please re-read all the equations with "(t)". There is no "cos(theta)" factor when "(t)" is present. The last term is known as the "interference term", page 388 of "Optics" by Hecht, 4th edition. When 90 theta 180, the sign of the last term is negative indicating destructive interference. When 0 = theta 90, the sign of the last term is positive indicating constructive interference. When theta = 90, there is zero interference which is what Part 1 of my web articles is based upon. But this applies to RMS voltages and average powers. You have extended this to instantaneous, for which a "cos(theta)" factor is inappropriate. This Pr.correction term has nothing to do with interference, ... Your argument is not with me but rather is with Eugene Hecht who defined that term as the "interference term" in "Optics". Have you even read his chapter on interference? If not, I would suggest that you do so. Two other enlightening chapters are on "Superposition" and "Coherency". Read it as Pr.correction(t) to emphasize that it is not average power of which I am writing. Then it is not interference. Note that there is no hint that Pr.correction needs to be stored when it is negative nor come from somewhere when it is positive. You're correct, there's no hint. It is spelled out in detail in "Optics". The possibilities are listed below. Your above statement is a conceptual violation of the conservation of energy principle. Of course not. Because the powers imputed to the constituent voltages of superposition do not represent actual energy flows. Conservation of energy only applies to powers that represent actual energy flows. In the absence of any other energy source or energy sink, localized destructive interference must exactly match the localized constructive interference magnitude in order to avoid a violation of the conservation of energy principle. This is why a Z0-match works. But you have to be cautious that you are applying conservation to powers that represent actual energy flows. Since one needs to know the constituent voltages to determine the sign of Pr.correction, why not just use superposition to compute the total voltage and then derive the power? That is what has extended this discussion to arguments over the past quarter century. That 30,000 foot method says nothing about where the ExH energy in the reflected wave goes. The irradiance (power density) equation with its defined "interference term" tells us exactly where all the energy goes and answers the question: What happens to the ExH energy in the reflected wave? It would be more valuable were you to thoroughly study and understand what is happening in a transmission line and then apply those learnings to ExH. The transmission line is easier to understand. The voltages, currents and time relationships can easily be precisely computed and measured. Once you have gained a full understanding of what power means in this easier to follow environment, extend that understanding to the meaning of power in an ExH, or optics environment where calculation and measurement is much more difficult. Here are the basic principles: When destructive interference occurs, there is "extra" energy left over from that isolated event. That energy must go somewhere. Here are the possibilities in a typical lossless RF transmitting system. 1. The source can throttle back on its energy output to compensate for the destructive interference energy. 2. Reactive components can store the destructive interference energy and return it to the network at a later time. 3. In the absence of (1) and (2) above, an RF energy wave is launched in a direction that allows the "extra" energy to leave the destructive event area. Or perhaps, these powers of which you speak do not represent actual energy flows and therefore your requirement that they need accounting is incorrect and all of your attempts to explain them, unnecessary. The difficulty of accounting for these powers is entirely consistent with them not representing the actual flow of energy. The last possibility is why we can observe reflected energy being redistributed back toward the load in the complete absence of single-wave reflections. When constructive interference occurs, there is "missing" energy needed to be supplied into that isolated event. That energy must come from somewhere. Here are the possibilities in a typical lossless RF transmitting system. 1. The source can simply supply the energy needed by the constructive interference event. 2. Reactive components can return stored energy to the network. 3. In the absence of (1) and (2) above, constructive interference energy *must* be supplied in real time by destructive interference between two other waves. Or possibly, the premise that these powers represent actual energy flows is flawed. ************************************************** ******* * The last possibility is how a Z0-match redistributes * * all of the reflected energy back toward the load when * * the physical reflection coefficient is not 1.0. * ************************************************** ******* The two-step process of redistributing 100% of the ExH reflected wave energy back toward the load is covered in my other energy analysis article on my web page at: http://www.w5dxp.com/energy.htm This turns out, however, just to be an ideosyncracy of the math, much like the way Pf-Pr is the actual energy flow in the transmission line because of the way that Vf and Vr are derived from Vactual and Iactual. This analysis also makes clear the nature of powers computed from the constituent voltages of superposition. These powers do not represent real energy flows. As discussed far above, real energy flows can be summed to test for conservation of energy. Translation: Don't bother trying to ascertain where the ExH component wave energy goes. Since the conservation of energy principle cannot be violated in reality, it is OK to violate it conceptually. Now where have I heard that argument before? :-) "I personally don't have a compulsion to understand where this power 'goes'." Do you really think that the ExH energy in a reflection from a mirror does not represent real energy flow? What can I say? That is what the math proves. The reflected power is a power computed from partial E and H fields that are being superposed, and we know that when you superpose, you need to compute the total voltage and current (or E and H) and then use that to compute the actual energy flow. It would be good, if just for a day, you let go of the idea that Preflected represents an actual energy flow. Explore the actual measureable behaviour of transmission lines without using the idea that Preflected represents an actual energy flow. Everything works. There is no violation of conservation of energy or any other fundamental physical law. And the explanations are much simpler. You will no longer find the question "where does the reflected power go?" relevant. You can terminate your quest. And as for "2*SQRT(P1*P2)cos(theta)", this will just be an idiosyncracy of the math that allows you to compute the total power, if you are presented with P1 and P2 (not being actual powers) that were computed from the constituent voltages of superposition; a useful tool when you can not measure the voltages (e.g. in optics), but not to be confused with reality. ....Keith |
The Rest of the Story
On Mon, 24 Mar 2008 16:15:21 GMT
Cecil Moore wrote: Roger Sparks wrote: To me, this shows that my traveling wave analysis on an instant basis is not correct because the energy can not be located precisely on a degree-by-degree scale. Yes, it is correct on the average over 360 degrees, but not instantaneously. We are missing something. What you are missing is the localized interference patterns within the individual cycles. The interference changes from destructive to constructive every 90 degrees. For every negative (destructive) interference term, there is an equal magnitude positive (constructive) interference term 90 degrees later. These, of course, average out to zero. Exactly the same thing happens when a coil or capacitor is present in a circuit. When the instantaneous voltage of a source is zero and thus delivering zero instantaneous power, a circuit capacitor is delivering energy back into the circuit that can be dissipated by a resistor. Central to traveling waves is the assumption that the wave is not compressable. The energy is assumed to flow in a consistantly predictable mannor that is linear and described by a sine wave. That assumption is violated when energy is delayed for reasons other than distance of travel, which is demonstrated in this example. Power is certainly compressible. One can stuff 100 amphere- hours into a battery in 2 hours and take 20 hours to remove it. Why can't 60 watts of instantaneous power be stuffed into a reactance and be removed 90 degrees later? I am not ready to suggest a cure for my traveling wave analysis. I only see that it does not work to my expectations. Your expectations seem to be based on a conservation of power principle which doesn't exist. There is no violation of linearity if the energy dissipation is delayed by 90 degrees or by ten billion years. I don't recall any published material where anyone tried to explain where the instantaneous energy goes while at the same time denying the possibility of interference. -- 73, Cecil http://www.w5dxp.com Hi Cecil, I feel better today. I think I have connected the dots and now have the spreadsheet showing that we really can use the traveling waves to solve the shorted transmission line problem on a instantaneous basis without the delay of energy into the next half cycle. Here is a link to the new spreadsheet. http://www.fairpoint.net/~rsparks/Sm...Reflection.pdf I used the logic and formula presented in my post "Subject: The Rest of the Story Date: Thu, 20 Mar 2008 10:07:44 -0700" You called it interference. Keith used your power equation and called the interference term a mathematical correction. It looks to me like the correction can be avoided by choosing the correct sin wave offset. Ultimately, the waves can be resolved into one more powerful wave carrying the power described by Keith's "false power" equation. This is demonstrated in a spreadsheet found at http://www.fairpoint.net/~rsparks/Re...em%20Power.pdf You need to take a look at the spreadsheets. I think they support the theory that we can track the power on an instant basis using traveling waves. -- 73, Roger, W7WKB |
The Rest of the Story
Keith Dysart wrote:
Cecil Moore wrote: Point is, energy can be stored and released at a later time. You earlier said that reactances do not store energy for release at a later time yet that is exactly what reactances do. Yes indeed. And what I have said, is that when this is happening it is always possible to identify the element which is storing the energy and provide the function that describes the energy flow in and out of the element. It is this identification and function that I keep asking for to back up the handwaving claim that you have been making. Good grief, Keith, do you not know how to track the energy flow into and out of a reactance during an RF cycle? Isn't that covered in EE201, "Alternating Current Circuits", by Kerchner and Corcoran, 3rd edition (c)1951? Quoting page 19: "The implication is that the inductive element receives energy from the source during one-quarter of a cycle of the applied voltage and returns exactly the same amount of energy to the driving source during the next one-quarter of a cycle." The equations are provided if you really need them. Hint: A shorted 1/8WL stub is inductive. Bzzt. Power is the rate of change of energy. Sorry, you are wrong about that. From the IEEE Dictionary: "power - the rate of generating, transferring, or using energy". Power is a rate, not a rate of change. The energy flow can be constant, i.e. rate of change equal zero. Please re-read all the equations with "(t)". There is no "cos(theta)" factor when "(t)" is present. I assume that exponential (phasor) notation for the instantaneous values of the interfering voltages could be used in which case there would indeed be a cos(theta) present. But this applies to RMS voltages and average powers. You have extended this to instantaneous, for which a "cos(theta)" factor is inappropriate. Nope, it's not. See above. Your same argument could extend to the real part of phasors in which case you could argue that the irradiance equation is bogus. Good luck on that one. If the math didn't work, it would have been discarded long ago and Hecht wouldn't have an entire chapter devoted to "Interference". Read it as Pr.correction(t) to emphasize that it is not average power of which I am writing. Then it is not interference. That statement makes it obvious that you don't understand interference. When instantaneous values are being used, if [V1(t)^2 + V2(t)^2] NOT= [V1(t) + V2(t)]^2, then interference is present. Did you miss Physics 201? Because the powers imputed to the constituent voltages of superposition do not represent actual energy flows. That statement is a violation of the wave reflection model. Do you really believe that when you look yourself in the mirror that those reflections are devoid of energy? If so, please feel free to prove your assertion. But you have to be cautious that you are applying conservation to powers that represent actual energy flows. Reflected waves contain energy whether from your mirror or from a mismatched load at the end of a transmission line. You are arguing that the wave reflection model is wrong. Please prove it. Or perhaps, these powers of which you speak do not represent actual energy flows and therefore your requirement that they need accounting is incorrect and all of your attempts to explain them, unnecessary. Yes, perhaps the wave reflection model is wrong but that makes your argument not with me, but with Ramo, Whinnery, Johnson, Chipman, Slater, Hecht, and Walter Maxwell. Good luck on winning that one. The difficulty of accounting for these powers is entirely consistent with them not representing the actual flow of energy. No, it is perfectly consistent with a large degree of ignorance which few people desire to alleviate. Ignoring the role of interference and lumping all the energy components into a mashed potato salad is one method of sweeping everything under the rug so you can ignore the problem instead of solving it. Or possibly, the premise that these powers represent actual energy flows is flawed. Feel free to prove the wave reflection model wrong. This turns out, however, just to be an ideosyncracy of the math, much like the way Pf-Pr is the actual energy flow in the transmission line because of the way that Vf and Vr are derived from Vactual Feel free to prove the math wrong. It would be good, if just for a day, you let go of the idea that Preflected represents an actual energy flow. I will do that the day that you prove those reflections from your mirror, that allow you to see yourself each morning, contain zero energy. Your concepts seem more like a religion than anything associated with reality. Your mantra seems to be: "If I don't understand it, it doesn't exist." -- 73, Cecil http://www.w5dxp.com |
The Rest of the Story
Roger Sparks wrote:
You need to take a look at the spreadsheets. Roger, in a nutshell, what is the bottom line? -- 73, Cecil http://www.w5dxp.com |
The Rest of the Story
Cecil Moore wrote:
[snip] That statement is a violation of the wave reflection model. Do you really believe that when you look yourself in the mirror that those reflections are devoid of energy? If so, please feel free to prove your assertion. [snip] Yes, perhaps the wave reflection model is wrong but that makes your argument not with me, but with Ramo, Whinnery, Johnson, Chipman, Slater, Hecht, and Walter Maxwell. Good luck on winning that one. Cecil, I have completely stayed away from any comments in this thread, but one thing has caught my attention. You repeatedly refer to the "wave reflection model" almost as if it was the equivalent of the Grand Unified Theory. I did a little bit of the cheap modern day replacement for research by Googling "wave reflection model". Some 455 references came back. Of course many of those references are irrelevant to the topic at hand, but of the ones that seemed to be related to transmission lines and/or RF, it appears that all of the references come back to you. I tried adding Ramo, Whinnery, Johnson, Chipman, Slater, Hecht, and Walter Maxwell to the search (one at a time) and came up with no hits, other than your references. Perhaps your specific interpretation of the writings of the masters to form your "wave reflection model" is part of the source of the disagreement. Do you have a concise reference to exactly what you mean by "wave reflection model"? There is no need to explain reflection, interference, conservation of energy, or any other standard wave phenomenon. I am merely seeking the definition of "wave reflection model" or a lead to any other reference that uses that terminology. 73, Gene W4SZ |
The Rest of the Story
Gene Fuller wrote:
I am merely seeking the definition of "wave reflection model" or a lead to any other reference that uses that terminology. The wave reflection model is, of course, the body of mathematics encompassing the reflection mechanics for EM waves. Everywhere except on r.r.a.a, it is a subset of the distributed network model. -- 73, Cecil http://www.w5dxp.com |
The Rest of the Story
Gene Fuller wrote:
I did a little bit of the cheap modern day replacement for research by Googling "wave reflection model". Some 455 references came back. That's strange. When I did the identical thing, 1,970,000 references came back. Wonder what is wrong with your computer? -- 73, Cecil http://www.w5dxp.com |
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Cecil Moore wrote:
Gene Fuller wrote: I did a little bit of the cheap modern day replacement for research by Googling "wave reflection model". Some 455 references came back. That's strange. When I did the identical thing, 1,970,000 references came back. Wonder what is wrong with your computer? When quotes are used, I get 455. Without quotes, I get about 297,000. Since I am looking for the exact expression, not just the three words somewhere in a web page, I use the quotes. I am using Firefox with plain 'ol Google. No special setups. In any case, you answered my question. "Wave reflection model" means nothing beyond ordinary electromagnetic theory. Big deal. 73, Gene W4SZ |
The Rest of the Story
On Mar 9, 6:33 pm, Chuck wrote:
On Sun, 9 Mar 2008 15:07:26 -0700 (PDT), K7ITM wrote: Note that, as far as I've been able to determine, Michelson did not have a coherent light source to shine into his interferometer, but still he saw interference patterns. Perhaps he had invented lasers It is said he used sodium vapor gas light (~589 nm). Coherent enough. Chuck Just a slight addition here. Before lasers, the way to get a coherent light source was to bottle-up a high-intensity, monochromatic source, such as the aforementioned sodium- vapor light, in a reflective cavity with a very small pinhole in its side. As the photons dribble out through the pinhole, they are forced into a somewhat phase-coherent wave train. This source was used in optical processors for synthetic-aperture imagery back in the 50's.... Jim, K7JEB |
The Rest of the Story
On Mar 25, 10:28*am, Cecil Moore wrote:
Keith Dysart wrote: Cecil Moore wrote: Point is, energy can be stored and released at a later time. You earlier said that reactances do not store energy for release at a later time yet that is exactly what reactances do. Yes indeed. And what I have said, is that when this is happening it is always possible to identify the element which is storing the energy and provide the function that describes the energy flow in and out of the element. It is this identification and function that I keep asking for to back up the handwaving claim that you have been making. Good grief, Keith, do you not know how to track the energy flow into and out of a reactance during an RF cycle? Isn't that covered in EE201, "Alternating Current Circuits", by Kerchner and Corcoran, 3rd edition (c)1951? Quoting page 19: "The implication is that the inductive element receives energy from the source during one-quarter of a cycle of the applied voltage and returns exactly the same amount of energy to the driving source during the next one-quarter of a cycle." The equations are provided if you really need them. Hint: A shorted 1/8WL stub is inductive. Instead of writing two lines identifying the element and providing the function describing its energy flow, you write 14 lines tell me I should do it. But my explanations do not require this element to store and return the "interference energy". You should consider that perhaps your inability to identify the element and its energy function really calls into question your concept of "interference energy" being stored and returned later. Bzzt. Power is the rate of change of energy. Sorry, you are wrong about that. *From the IEEE Dictionary: "power - the rate of generating, transferring, or using energy". Power is a rate, not a rate of change. The energy flow can be constant, i.e. rate of change equal zero. When energy is transferred, the quantity is decreasing in the supplier and increasing in the receiver. From the supplier's perspective, this is a negative flow and from the receiver's perspective, a positive flow. In calculus terms, energy flow is the derivative of the quantity of energy, i.e. the rate of change of the amount of energy. The slope of the curve recording the amount of energy can be negative, even though the amount of energy is always positive. Please re-read all the equations with "(t)". There is no "cos(theta)" factor when "(t)" is present. I assume that exponential (phasor) notation for the instantaneous values of the interfering voltages could be used in which case there would indeed be a cos(theta) present. No. "cos(theta)" only appears in the equations describing the average, and not in those equations that describe the actual function of time. [snip] Read it as Pr.correction(t) to emphasize that it is not average power of which I am writing. Then it is not interference. That statement makes it obvious that you don't understand interference. When instantaneous values are being used, if [V1(t)^2 + V2(t)^2] NOT= [V1(t) + V2(t)]^2, then interference is present. Did you miss Physics 201? I suppose, if you want to rename superposition as interference. But none of my basic circuit theory books use the word interference when discussing superposition. Because the powers imputed to the constituent voltages of superposition do not represent actual energy flows. That statement is a violation of the wave reflection model. Do you really believe that when you look yourself in the mirror that those reflections are devoid of energy? If so, please feel free to prove your assertion. If the powers imputed to the constituent voltages of superposition did represent actual energy flows, then you would be able to simply add them to get the total flow, since energy can not be created or destroyed. The fact that a correction needs to be applied when adding them is proof that they can not be actual energy flows. But you know that, and that is why you have to search for where this correction, that which you call the "interference energy", goes. Because only if you can account for it, can you claim that it is an actual energy flow, which is needed to make you explanations agree with conservation of energy. But in this example you can not account for this "interference energy". You have not identified the element that stores it nor being able to obtain a function which describes the flow into that element. You should take this as a reason to call into question the whole idea that this "interference energy" is an actual energy flow. But you have to be cautious that you are applying conservation to powers that represent actual energy flows. Reflected waves contain energy whether from your mirror or from a mismatched load at the end of a transmission line. You are arguing that the wave reflection model is wrong. Please prove it. If *your* "wave reflection model" includes the idea that Pref always represents an actual energy flow, then *your* "wave reflection model" is wrong. Or perhaps, these powers of which you speak do not represent actual energy flows and therefore your requirement that they need accounting is incorrect and all of your attempts to explain them, unnecessary. Yes, perhaps the wave reflection model is wrong but that makes your argument not with me, but with Ramo, Whinnery, Johnson, Chipman, Slater, Hecht, and Walter Maxwell. Good luck on winning that one. I am not convinced. It is clear that *your* "wave reflection model" is wrong, but I have not seen these other authors invest any effort in trying to explain where the reflected power goes. Perhaps they realized it was a meaningless question and their "wave reflection models" do not require that the Pref represent an actual energy flow. The difficulty of accounting for these powers is entirely consistent with them not representing the actual flow of energy. No, it is perfectly consistent with a large degree of ignorance which few people desire to alleviate. Ignoring the role of interference and lumping all the energy components into a mashed potato salad is one method of sweeping everything under the rug so you can ignore the problem instead of solving it. I am still waiting for the simple answer as to which element stores and returns this "interference energy" and the function that describes the flow into this element. Or possibly, the premise that these powers represent actual energy flows is flawed. Feel free to prove the wave reflection model wrong. That your "wave reflection model" is inconsistent with conservation of energy (until you identify the storage element and its energy transfer function) should be proof enough. This turns out, however, just to be an ideosyncracy of the math, much like the way Pf-Pr is the actual energy flow in the transmission line because of the way that Vf and Vr are derived from Vactual Feel free to prove the math wrong. The math is correct. It is the interpretation that is in error. Pf-Pr is always equal to Pnet simply because of the way that Vfor and Vref are computed. Even though Pf-Pr adds to the actual measured energy flow, it does not mean that Pf and Pr are actual energy flows. They MUST add simply becase of the way they are computed. The same is true for some of the "proofs" in your other papers. The successful equalities are simply a consequence of the way the numbers being added are computed. A successful equality does not necessarily prove an interpretation. It would be good, if just for a day, you let go of the idea that Preflected represents an actual energy flow. I will do that the day that you prove those reflections from your mirror, that allow you to see yourself each morning, contain zero energy. This is indeed the root of the problem. You need to let go of the mirror just long enough to get over the hump. As it stands, whenever you approach the hump, you think about the mirror and refuse to see what might be on the other side of the hump. That is why I suggest letting go of the mirror just for a short while. Explore to see if there exists a completely self consistent set of explanations on the other side of the hump. You will find it to be so. But this can only happen if you let go of the mirror long enough to get over the hump. If it doesn't work out, you can always pick up the mirror again. There is nothing to lose by temporarily doing some exploration without the mirror. [snip] ...Keith |
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