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Richard Clark wrote:
... 73's Richard Clark, KB7QHC Richard: In my course of study, I was forced to take a class in human psychology--I hated it--its' use I could not fathom, to one engaged in the technical aspects of "the real world" it seemed a waste. However, that class was all about running into the likes of you. You are an actor on a stage, yet we all wish to view NO performance. You are a writer, in your imagination--yet we have no interest in your book. You are all important--to yourself, but you have NO importance to me. You are a spoiled child who will even accept "negative attention" as opposed to "no attention at all"--and in all actuality--that is what you truly deserve. You are a mess man, get a hold of yourself ... anyone who would even lend a hand in your support is an idiot--OWN IT MAN! Only an idiot can befriend you at the present time--grow up ... Now, 3's :-) JS |
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John Smith wrote:
Richard Clark wrote: ... 73's Richard Clark, KB7QHC Richard: In my course of study, I was forced to take a class in human psychology--I hated it--its' use I could not fathom, to one engaged in the technical aspects of "the real world" it seemed a waste. However, that class was all about running into the likes of you. Don't sweat it, "John". As you've stated, you couldn't fathom "its' use." You are an actor on a stage, yet we all wish to view NO performance. Who's "we", "John"? For whom do you speak? You are a writer, in your imagination--yet we have no interest in your book. Who is "we"? I find Richard's posts quite entertaining. You are all important--to yourself, but you have NO importance to me. Get over it, "John". It isn't all about you, whoever you are. Dave K8MN |
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Dave Heil wrote:
Heil, you are an idiot. You are, perhaps the biggest idiot I have run into in the news groups, and that is saying something, Richard is second--only to you ... ROFOL Keep on truckin', if persistence counts, you have one thing going for you. :-) JS |
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Jim Lux wrote:
The circuits I am thinking of sample a length of line (NOT A POINT) so the sample records average voltage (or current) from a period of time. Many simple reflectometer designs do indeed sample the line over a short length of line, and that short length may be 100mm or more. Ideally, they would take the sample at a point. (Since a point has zero length, I can't quickly think of a sampling technique that truly takes a point sample.) The voltage sample is easy... measure the voltage using an infinitely thin probe. The current sample is measured in a similar way by measuring the magnetic field over a infinitely small segment of the conductor. There are sensitivity issues or bandwidth issues, but there are lots of very, very small magnetic field probe schemes around. Agreed; we're discussing principles here, and the issue of single-point sampling is mostly a practical one. In principle, we can always choose a method of sampling that doesn't require a finite length of line. Within the limits of our skill and imagination, we can also make the current and voltage pickups physically smaller, so that they occupy less length along the line. Or if skill and imagination fail, we can shift the whole discussion to longer and longer wavelengths, to make the error as small as we like. It may not be practical, but no general principles are being broken. The issue of single-point sampling is interesting in its own right, but in this much wider discussion it is only a minor detail. In order to move on with the wider discussion, let's agree to assume that single-point sampling always *can* be achieved, within the accuracy that we require. If one says, "point sample" == "less than 1/1000 wavelength), I think it's actually pretty straight forward, certainly for 100 MHz or less. (3mm is 1/1000 lambda). Even for practical instruments, this particular source of error is usually quite small. At any one frequency, it is always possible to null the bridge in the reverse direction, so that the voltage and current samples (as described by Cecil) will cancel. How well the cancellation holds over a wider frequency band will depend on the choice of bridge circuit and the way it is constructed. -- 73 from Ian GM3SEK 'In Practice' columnist for RadCom (RSGB) http://www.ifwtech.co.uk/g3sek |
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John Smith wrote:
Dave Heil wrote: Heil, you are an idiot. You are, perhaps the biggest idiot I have run into in the news groups, and that is saying something... But we are left wondering what it is that is being said. After all, you're an anonymous CBer who chastises others from the shadows. You haven't the courage of your convictions, "John". ...Richard is second--only to you ... ROFOL Richard is quite obviously an intelligent person. That alone seems enough to chafe you. Keep on truckin', if persistence counts, you have one thing going for you. :-) Oh, I'm persistent. I can punctuate and spell. I'm interested in antennas and find your stuff distracting. I find it amusing that someone of your ilk attacks Richard. I've learned much from reading his posts and those of W7EL. W8JI's material was most helpful in installing a beverage antenna. On the other hand, I've never learned anything useful from you. Dave K8MN |
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Roy Lewallen wrote:
My postulate is that Newton was wrong: moving objects come to a rest without any external applied force. Every observation made supports this. There's no need to consider what happens in a frictionless environment, since such a thing doesn't exist. Isn't that like lossless wires, perfect grounds, and other such? The conditions that cause an object to slow and stop in real life are the proof of the law. To the contrary, it proves Newton correct. The forces act just as they should. - 73 de Mike N3LI - |
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Dave Heil wrote:
... But we are left wondering what it is that is being said. After all, you're an anonymous CBer who chastises others from the shadows. You haven't the courage of your convictions, "John". 10-fer 'gud buddy! ...Richard is second--only to you ... ROFOL Richard is quite obviously an intelligent person. That alone seems enough to chafe you. LOL! I am at a loss for words ... Keep on truckin', if persistence counts, you have one thing going for you. :-) Oh, I'm persistent. I can punctuate and spell. I'm interested in antennas and find your stuff distracting. I find it amusing that someone of your ilk attacks Richard. I've learned much from reading his posts and those of W7EL. W8JI's material was most helpful in installing a beverage antenna. On the other hand, I've never learned anything useful from you. My goodness! Keep up the good work, you parents are pulling for you--I am sure ... Dave K8MN Time to hammer down, gonna leave this clown-town ... 3's 'gud buddy!, JS |
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Dave Heil wrote:
[...] Without a personality to attack, the "fish out of water" become quite apparent ... JS |
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Cecil Moore wrote: Jim Kelley wrote: Cecil Moore wrote: Jim Kelley wrote: Problem is that it conflicts with the predictions made by the power propagation model. (The politically correct name is the Joules/sec propagation model.) That model shows that only a single reflection of power is needed to explain the whole thing. Of course in some cases the wave of power has to figure out how to turn around and go back the other direction after it's been cancelled in order to conserve energy. (A problem it wouldn't have to solve had it not violated it in the first place.) Admittedly, some of the details have yet to be worked out. :-) Wow Jim, you need to repeat Fields and Waves 310. :-) You have misunderstood virtually every principle of the wave reflection model. I wouldn't presume to take credit for any of the above. I learned it on r.r.a.a. from someone who I think needs to take Fields and Waves 1. :-) If you are talking about me, you have either misunderstood what I said or you enjoy bearing false witness. Here's a quote from my 2005 magazine article at: http://www.w5dxp.com/energy.htm Hi Cecil - Yes, I'm very familiar with that article. You've already posted a link to it dozens of times on this newsgroup. It very clearly illustrates exactly those thing which I may have somewhat more 'colorfully' restated above, and more. It includes equations with variables for forward and reflected power all throughout, a reference to a supposed "4th mechanism of reflection" (that's the magical way in which waves of power and energy change direction), and illustrations with arrows named Pref showing how power is reflected at impedance discontinuities. Back when our corresponence was more cordial, I advised you not to write those things. And now you'd like to deny having done it; all the while portraying me as a liar. You're beautiful, man. 73, ac6xg |
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Jim Kelley wrote:
Yes, I'm very familiar with that article. You've already posted a link to it dozens of times on this newsgroup. It very clearly illustrates exactly those thing which I may have somewhat more 'colorfully' restated above, and more. It includes equations with variables for forward and reflected power all throughout, Yes, forward and reflected power measured at a *FIXED* measurement point. There is no "power flow" anywhere in my article. Energy does the flowing. Power is the measurement at a *FIXED* measurement point of that energy flow past that *FIXED* point. Did you note the use of the word, "FIXED"? Even though all my references, including the IEEE Dictionary allow for "power flow", I avoided it in my article as a favor to you. a reference to a supposed "4th mechanism of reflection" (that's the magical way in which waves of power and energy change direction), Yes, that may be somewhat original and therefore frightening for you. Galileo would have scared you to death. If, as Walter C. Johnson says, interference can *cause* standing waves, it can probably also cause reflections at an impedance discontinuity through wave cancellation. You are going to have to do more than wave your hands to prove otherwise. Not refusing to answer my questions about my examples would be a good start. Remember your absolute refusal to compute the total joules/sec after the first internal reflection arrived at the thin-film anti-reflective coating in my example? When you learn how to properly manage irradiance, get back to us. and illustrations with arrows named Pref showing how power is reflected at impedance discontinuities. No! No! No! Power is NOT reflected at an impedance discontinuity. Those are Poynting vectors. Energy is reflected and that reflected energy is measured and called "reflected power". Reflected power is not moving. You continue to get it wrong. The reflected power is acutally reflected energy measured flowing past a *FIXED* point near the impedance discontinuity. There are joules in the reflected wave. The joules in the reflected wave are measured flowing past a *FIXED* measurement point. But, of course, I have explained all of this to you before yet you continue bear false witness after all these years. Back when our corresponence was more cordial, I advised you not to write those things. And now you'd like to deny having done it; all the while portraying me as a liar. You're beautiful, man. I changed my article just to make you happy. You obviously have misunderstood, either through lack of processing power, ignorance, or deliberately. I would guess it is deliberate. -- 73, Cecil http://www.w5dxp.com |
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Michael Coslo wrote:
Roy Lewallen wrote: My postulate is that Newton was wrong: moving objects come to a rest without any external applied force. Every observation made supports this. There's no need to consider what happens in a frictionless environment, since such a thing doesn't exist. Isn't that like lossless wires, perfect grounds, and other such? The conditions that cause an object to slow and stop in real life are the proof of the law. To the contrary, it proves Newton correct. The forces act just as they should. - 73 de Mike N3LI - To repeat my posting of Dec. 8: -------------- This would be funny if it weren't sad. This newsgroup is one of the few places I can think of where the silly statement I posted about moving bodies and friction would be taken seriously. But it's really no surprise, since it's much less unreasonable than the imaginative alternative theories which are seriously presented, and just as seriously argued, here daily. My postulate about objects in motion was a parody of Cecil's rejection of theoretical cases on the basis that they can't exist in practice, my intent being to show how such a rejection leads to incorrect results. But I see it's drawing the same serious response as Cecil's and Art's postings. All that's missing is one of Richard's quotes from Terman and support from Derek. -------------- Roy Lewallen, W7EL |
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Roy Lewallen wrote:
My postulate about objects in motion was a parody of Cecil's rejection of theoretical cases on the basis that they can't exist in practice, Roy, once again you distort what I have said. I did NOT reject any theoretical cases. I said I personally don't have time to consider those cases as my daughter is facing emergency surgery in New York state and I am standing by to hop a plane during the Christmas season rush. If you know more about my personal time than I do, please let me know exactly how you accomplish that feat. If your argument is that gurus know everything, I will certainly understand. You have used that argument before. -- 73, Cecil http://www.w5dxp.com |
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Roy Lewallen wrote:
This would be funny if it weren't sad. I'll tell you what would be funny if it weren't sad. You present yourself as some omniscient guru on this newsgroup yet you recently showed your absolute ignorance of standing waves and the math behind that subject. Most of the knowledgeable people on this newsgroup now know that, as far as standing waves go, you are just a flimflam man. I am amazed that you have the balls to post anything else after that fiasco. -- 73, Cecil http://www.w5dxp.com |
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Roger wrote:
To elaborate, the power (Pt) resident on the transmission line will always be the sum of forward power and reflected power. That statement is slightly misleading. The length of the transmission line can be converted to time, e.g. one microsecond long. If the forward power is 100 joules/sec and the reflected power is 50 joules/sec, the total energy in the one microsecond long transmission line will be 100+50 = 150 microjoules. Energy is what is flowing in the feedline and must be conserved, not power. The technically correct way to say what you are trying to say is: There is exactly the amount of energy resident in the transmission line needed to support the steady-state forward and reflected power readings. I realize that I am picking nits. -- 73, Cecil http://www.w5dxp.com |
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On Dec 11, 4:21 pm, Cecil Moore wrote:
Jim Kelley wrote: Yes, I'm very familiar with that article. You've already posted a link to it dozens of times on this newsgroup. It very clearly illustrates exactly those thing which I may have somewhat more 'colorfully' restated above, and more. It includes equations with variables for forward and reflected power all throughout, Yes, forward and reflected power measured at a *FIXED* measurement point. There is no "power flow" anywhere in my article. Energy does the flowing. Power is the measurement at a *FIXED* measurement point of that energy flow past that *FIXED* point. Did you note the use of the word, "FIXED"? Even though all my references, including the IEEE Dictionary allow for "power flow", I avoided it in my article as a favor to you. a reference to a supposed "4th mechanism of reflection" (that's the magical way in which waves of power and energy change direction), Yes, that may be somewhat original and therefore frightening for you. Galileo would have scared you to death. If, as Walter C. Johnson says, interference can *cause* standing waves, it can probably also cause reflections at an impedance discontinuity through wave cancellation. You are going to have to do more than wave your hands to prove otherwise. Not refusing to answer my questions about my examples would be a good start. Remember your absolute refusal to compute the total joules/sec after the first internal reflection arrived at the thin-film anti-reflective coating in my example? When you learn how to properly manage irradiance, get back to us. and illustrations with arrows named Pref showing how power is reflected at impedance discontinuities. No! No! No! Power is NOT reflected at an impedance discontinuity. Those are Poynting vectors. Energy is reflected and that reflected energy is measured and called "reflected power". Reflected power is not moving. You continue to get it wrong. The reflected power is acutally reflected energy measured flowing past a *FIXED* point near the impedance discontinuity. There are joules in the reflected wave. The joules in the reflected wave are measured flowing past a *FIXED* measurement point. But, of course, I have explained all of this to you before yet you continue bear false witness after all these years. Back when our corresponence was more cordial, I advised you not to write those things. And now you'd like to deny having done it; all the while portraying me as a liar. You're beautiful, man. I changed my article just to make you happy. You obviously have misunderstood, either through lack of processing power, ignorance, or deliberately. I would guess it is deliberate. The debate has never been aoout a little looseness in the terminology; i.e. does "power flow" or does "energy flow". That is a straw man of your own making. The debate is over much more fundamental issues. ....Keith |
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On Dec 11, 10:34 pm, Roger wrote:
Keith Dysart wrote:On Dec 9, 9:36 pm, wrote:The constantly-in-phase traveling wave concept requires the difficult-to-believe observation that a directional ammeter placed very near the end of an open transmission line will read the same current as if it were placed at the source end. Perhaps someone can perform that experiment some day, but I can not imagine how it can be done without placing a load on the line, thus invalidating the initial assumptions.The experiment will show the expected result but will not help understand why. For that, examination of the measurements and arithmetic performed by a directional ammeter is useful. Below, all voltages and currents are instantaneous. Total voltage, Vt = Vf + Vr Total current, It = If - Ir Vf = If * Z0 Vr = Ir * Z0 Substituting.... Vt = (If + Ir) * Z0 Ir = Vt/Z0 - If If = It + Ir If = It + (Vt/Z0 - If) If = (It + Vt/Z0)/2 Similarly, Ir = (It - Vt/Z0)/2 The directional ammeter measures instantaneous Vt and It, does the above arithmetic and presents If. A directional ammeter that presents a single number rather than the time varying If has probably converted the instantaneous values to RMS. Examing It and Vt at various points on the line and doing the above arithmetic will reveal why the same value for If is obtained everywhere. Directional wattmeters are more common than directional ammeters. A directional wattmeter does the above arithmetic then squares If, multiplies by Z0 and presents the results in watts. All this from just measuring Vt and It. ...KeithHi Keith, Thanks to you and others for responding on this side issue. It was very helpful to me and resulted in a vast improvement in how I understood the theory behind directional watt meters. I had the misconception that current pickup over some lineal distance of transmission line was NECESSARY for the device to work, but now clearly understand that instantaneous measurement points suffice (and that instantaneous current measurement may be impossible). After considerable thought, I think the math you presented above is for one of two cases of reflective waves, the reflection from a higher impedance load. When the load is less than the Zo of the line, the currents add but voltages subtract. Right? I don't think so. Vt = Vf + Vr, It = If - Ir, Vf = If * Z0 and Vr = Ir * Z0 are the fundamental equations defining forward and reverse waves. Perhaps you arrive at two choices because sometimes Vr and Ir are negative, which after simplification appears to give an alternate form? The end result is the same for both cases. This is good. If you chase the signs, though, I think you will find that there is only one case. We probably should not toss Power into the mix until agreement is reached on this. Power is fraught with issues which seriously confuse some. ...Keith |
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Keith Dysart wrote:
The debate has never been about a little looseness in the terminology; Actually, I believe that every disagreement between Jim Kelley and myself has been semantic in nature. There are no technical fundamentals upon which we disagree. We both agree that a light wave from Alpha Centauri that hits the earth has transferred energy. We disagree about a light wave from Alpha Centauri that misses the earth. I say the energy in the light wave is in the process of being transferred. Jim disagrees. The debate is over much more fundamental issues. Like what? The definition of "transfer"? -- 73, Cecil http://www.w5dxp.com |
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Keith Dysart wrote:
On Dec 11, 10:34 pm, Roger wrote: When the load is less than the Zo of the line, the currents add but voltages subtract. Right? I don't think so. Vt = Vf + Vr, It = If - Ir, Vf = If * Z0 and Vr = Ir * Z0 are the fundamental equations defining forward and reverse waves. I think Roger is talking about the phase shift at a reflection point. If ZL Z0, the current reverses phase, i.e. It = |If| - |Ir| = 0. If ZL Z0, the voltage reverses phase, i.e. Vt = |Vf| - |Vf| = 0 The sign on the reflected current is just a directional convention left over from DC and is unnecessary as the phase angle of the phasor values takes care of the signs. Interestingly, the field of optics has a different convention. -- 73, Cecil http://www.w5dxp.com |
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Keith Dysart wrote:
The debate is over much more fundamental issues. I guess that depends upon the definition of "fundamental" doesn't it? :-) Hint: Virtually every verbal disagreement is semantic. -- 73, Cecil http://www.w5dxp.com |
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Cecil Moore wrote:
I think Roger is talking about the phase shift at a reflection point. If ZL Z0, the current reverses phase, i.e. It = |If| - |Ir| = 0. If ZL Z0, the voltage reverses phase, i.e. Vt = |Vf| - |Vf| = 0 Left out a few words - should be: It = |If| - |Ir| = 0 at an open-circuit. Vt = |Vf| - |Vr| = 0 at a short-circuit. -- 73, Cecil http://www.w5dxp.com |
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Roy Lewallen wrote:
Michael Coslo wrote: Roy Lewallen wrote: My postulate is that Newton was wrong: moving objects come to a rest without any external applied force. Every observation made supports this. There's no need to consider what happens in a frictionless environment, since such a thing doesn't exist. Isn't that like lossless wires, perfect grounds, and other such? The conditions that cause an object to slow and stop in real life are the proof of the law. To the contrary, it proves Newton correct. The forces act just as they should. - 73 de Mike N3LI - To repeat my posting of Dec. 8: -------------- This would be funny if it weren't sad. This newsgroup is one of the few places I can think of where the silly statement I posted about moving bodies and friction would be taken seriously. But it's really no surprise, since it's much less unreasonable than the imaginative alternative theories which are seriously presented, and just as seriously argued, here daily. My postulate about objects in motion was a parody of Cecil's rejection of theoretical cases on the basis that they can't exist in practice, my intent being to show how such a rejection leads to incorrect results. But I see it's drawing the same serious response as Cecil's and Art's postings. All that's missing is one of Richard's quotes from Terman and support from Derek. Okay, I get it now. I came in late on this one and was reading it literally. - 73 de Mike N3LI - |
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Cecil Moore wrote:
Actually, I believe that every disagreement between Jim Kelley and myself has been semantic in nature. There are no technical fundamentals upon which we disagree. I don't care about your use of words, Cecil. I am only concerned with some of the concepts that you describe. 73, Jim AC6XG |
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Jim Kelley wrote:
Cecil Moore wrote: Actually, I believe that every disagreement between Jim Kelley and myself has been semantic in nature. There are no technical fundamentals upon which we disagree. I don't care about your use of words, Cecil. I am only concerned with some of the concepts that you describe. I use words to describe those concepts. You and I do not agree on the definitions of those words. Reality is what it is. It is the different definitions that we are using that is the problem. For instance, what if I am using a different definition than you are for "concepts" in your posting above? What if you were writing in a language that I didn't understand? The outcome would be similar to what we have now. -- 73, Cecil http://www.w5dxp.com |
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Jim Kelley wrote:
I am only concerned with some of the concepts that you describe. When you repeat those concepts back to me, they bear no resemblance to the concepts that I am trying to describe. That is proof that our disagreements are semantic. (The only other possibility is that you are unethical and are deliberately bearing false witness against me.) I use words to describe my concepts. You and I do not agree on the definitions of those words. Reality is what it is. It is the different definitions that we are using that is the problem. "Transfer" is obviously one of those words. I say all EM waves transfer energy. You say not all EM waves transfer energy. It is simply that we are using different definitions of the word "transfer". There are many other words for which we have different definitions. You and I might as well be trying to communicate in two foreign languages that neither one of us understand. -- 73, Cecil http://www.w5dxp.com |
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Cecil Moore wrote:
Jim Kelley wrote: I am only concerned with some of the concepts that you describe. When you repeat those concepts back to me, they bear no resemblance to the concepts that I am trying to describe. To you, they may not. But those concepts remain just as ludicrous no matter who describes them. :-) That is proof that our disagreements are semantic. (The only other possibility is that you are unethical and are deliberately bearing false witness against me.) The obvious possibility being dismissed out of hand is the one where you are wrong and someone else is right. I use words to describe my concepts. You and I do not agree on the definitions of those words. Yes. Others also use words, and there are cases where your understanding of the meaning of the words is not necessarily the same as the meaning intended by the author. We know this by comparing the things you say about physics with fundamental principles of physics. It is simply that we are using different definitions of the word "transfer". If that is the case then I am using the definition pertinent to the physics of our discussion, and you are using whichever one you think will prevent your argument from containing a false statement. You and I might as well be trying to communicate in two foreign languages that neither one of us understand. But only if it suits the purposes of internet one-upsmanship, apparently. 73, ac6xg |
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On Dec 12, 6:03 pm, Cecil Moore wrote:
Jim Kelley wrote: I am only concerned with some of the concepts that you describe. When you repeat those concepts back to me, they bear no resemblance to the concepts that I am trying to describe. That is proof that our disagreements are semantic. (The only other possibility is that you are unethical and are deliberately bearing false witness against me.) I use words to describe my concepts. You and I do not agree on the definitions of those words. Reality is what it is. It is the different definitions that we are using that is the problem. "Transfer" is obviously one of those words. I say all EM waves transfer energy. You say not all EM waves transfer energy. It is simply that we are using different definitions of the word "transfer". There are many other words for which we have different definitions. Can you expand on the two different interpretations of "transfer" that will bring these views into alignment? Perhaps you really are disagreeing on whether EM waves always transfer energy (using the common definition of "transfer"). ....Keith |
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Jim Kelley wrote:
The obvious possibility being dismissed out of hand is the one where you are wrong and someone else is right. No, that is not dismissed out of hand. I enjoy being wrong because I always learn something new. You have not proved me wrong because you haven't even understood what I said. When you repeat what you think I said, and it is not what I said, there is something wrong besides someone being technically incorrect and someone being technically correct. -- 73, Cecil http://www.w5dxp.com |
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Keith Dysart wrote:
Can you expand on the two different interpretations of "transfer" that will bring these views into alignment? Perhaps you really are disagreeing on whether EM waves always transfer energy (using the common definition of "transfer"). Jim refuses to provide a reference for his definition of "transfer". My unabridged Webster's has 20 definitions for the word including, "to be moved from one place to another". I say the light waves from Alpha Centauri are transferring, i.e. moving energy from that star to other points in the universe. The Poynting vector for those light waves can be computed if necessary. EM waves cannot exist without energy. -- 73, Cecil http://www.w5dxp.com |
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Keith Dysart wrote: clip text........... After considerable thought, I think the math you presented above is for one of two cases of reflective waves, the reflection from a higher impedance load. When the load is less than the Zo of the line, the currents add but voltages subtract. Right? I don't think so. Vt = Vf + Vr, It = If - Ir, Vf = If * Z0 and Vr = Ir * Z0 are the fundamental equations defining forward and reverse waves. Perhaps you arrive at two choices because sometimes Vr and Ir are negative, which after simplification appears to give an alternate form? The end result is the same for both cases. This is good. If you chase the signs, though, I think you will find that there is only one case. We probably should not toss Power into the mix until agreement is reached on this. Power is fraught with issues which seriously confuse some. ....Keith I can see that I need to further explain. My analysis always begins with the source because the first formation of the wave comes from the source, then travels through the transmission line system. The source defines the wave only until the wave reaches any discontinuity(s) or the line end. Thereafter, discontinuities and end conditions define the system,. Why might I say that? Initiation of the wave at the source results in a sine wave with the impedance of the transmission line, and the power and frequency of the source. This is a steady state condition until the first discontinuity or reflection point is reached by the traveling wave. Each successive reflection point (discontinuity) reflects power which travels back to the source and changes the feed point impedance conditions. The most distant possible reflection point is the end of the transmission line (ignoring reflections which might occur on the antenna) and might be an open circuit, a reactive resistance, or a short circuit. Any power reflected from the end will change the measured impedance found at any point on the transmission line all the way back to the source, and will define the steady state conditions of the system. If we accept that the steady state conditions are defined by the load, then we should examine the conditions on the source side of the load, assuming it is the end of the transmission line. The forward wave spawns the reflective wave in one of two ways, one way of load resistance higher than line impedance, and a second way of load resistance lower than line impedance. In both cases the power of both forward and reflective wave add, but the voltages and currents both add and subtract. (Cecil explained it very well in his follow up postings. Thanks Cecil.) I presented the power equations to illustrate the two conditions. It is convenient that both cases result in the same math for the directional watt meter. 73, Roger, W7WKB |
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On Wed, 12 Dec 2007 21:52:48 -0800, Roger wrote:
!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" html head meta content="text/html;charset=ISO-8859-1" http-equiv="Content-Type" title/title /head body bgcolor="#ffffff" text="#000000" br Hi Roger, 99.9999% of posters here use unformatted text which makes responses very readable. 73's Richard Clark, KB7QHC |
Loading Coils; was : Vincent antenna
On Dec 13, 12:52 am, Roger wrote:
Keith Dysart wrote: clip text...........After considerable thought, I think the math you presented above is for one of two cases of reflective waves, the reflection from a higher impedance load. When the load is less than the Zo of the line, the currents add but voltages subtract. Right?I don't think so. Vt = Vf + Vr, It = If - Ir, Vf = If * Z0 and Vr = Ir * Z0 are the fundamental equations defining forward and reverse waves. Perhaps you arrive at two choices because sometimes Vr and Ir are negative, which after simplification appears to give an alternate form?The end result is the same for both cases.This is good. If you chase the signs, though, I think you will find that there is only one case. We probably should not toss Power into the mix until agreement is reached on this. Power is fraught with issues which seriously confuse some. ...KeithI can see that I need to further explain. My analysis always begins with the source because the first formation of the wave comes from the source, then travels through the transmission line system. The source defines the waveonlyuntil the wave reaches any discontinuity(s) or the line end. Thereafter, discontinuities and end conditions define the system,. Why might I say that? Initiation of the wave at the source results in a sine wave with the impedance of the transmission line, and the power and frequency of the source. This is a steady state condition until the first discontinuity or reflection point is reached by the traveling wave. Each successive reflection point (discontinuity) reflects power which travels back to the source and changes the feed point impedance conditions. The most distant possible reflection point is the end of the transmission line (ignoring reflections which might occur on the antenna) and might be an open circuit, a reactive resistance, or a short circuit. Any power reflected from the end will change themeasuredimpedance found atany pointon the transmission line all the way back to the source, and will define the steady state conditions of the system. If we accept that the steady state conditions are defined by the load, then we should examine the conditions on the source side of the load, assuming it is the end of the transmission line. The forward wavespawnsthe reflective wave in one of two ways, one way of load resistance higher than line impedance, and a second way of load resistance lower than line impedance. In both cases the power of both forward and reflective wave add, but the voltages and currents both add and subtract. (Cecil explained it very well in his follow up postings. Thanks Cecil.) I presented the power equations to illustrate the two conditions. It is convenient that both cases result in the same math for the directional watt meter. I'd still suggest that you have the cart and the horse backwards. The math came first and that is why all the example cases turn out to be consistent with the math. And just for completeness... The fundamental equations also work when: - the signal is not sinusoidal, e.g. pulse, step, square, ... - rather than a load at one end, there is a source at each end - the sources at each end produce different arbitrary functions - the arbitrary functions at each end are DC sources It is highly instructive to compute the forward and reverse voltage and current (and then power) for a line with the same DC voltage applied to each end. ....Keith ....Keith |
Loading Coils; was : Vincent antenna
Richard Clark wrote:
On Wed, 12 Dec 2007 21:52:48 -0800, Roger wrote: !DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" html head meta content="text/html;charset=ISO-8859-1" http-equiv="Content-Type" title/title /head body bgcolor="#ffffff" text="#000000" br Hi Roger, 99.9999% of posters here use unformatted text which makes responses very readable. 73's Richard Clark, KB7QHC Thanks Richard, I will use text from now on. Sorry for the inconvenience. Roger |
Loading Coils; was : Vincent antenna
Roger wrote:
... Thanks Richard, I will use text from now on. Sorry for the inconvenience. Roger HTML is not a problem for many of us, any decade old/decent newsreader handles it fine--if you have .html enabled ... Regards, JS |
Loading Coils; was : Vincent antenna
Keith Dysart wrote:
On Dec 13, 12:52 am, Roger wrote: Keith Dysart wrote: Clipping text............. I'd still suggest that you have the cart and the horse backwards. The math came first and that is why all the example cases turn out to be consistent with the math. And just for completeness... The fundamental equations also work when: - the signal is not sinusoidal, e.g. pulse, step, square, ... - rather than a load at one end, there is a source at each end - the sources at each end produce different arbitrary functions - the arbitrary functions at each end are DC sources It is highly instructive to compute the forward and reverse voltage and current (and then power) for a line with the same DC voltage applied to each end. ...Keith ...Keith Interesting! The important thing is to get answers that agree with our experiments. I have done some computations for DC voltage applied to transmission lines. The real surprise for me came when I realized that transmission line impedance could be expressed as a function of capacitance and the wave velocity. Z0 = 1/cC where c is the velocity of the wave and C is the capacitance of the transmission line per unit length. 73, Roger , W7WKB |
Loading Coils; was : Vincent antenna
Roger wrote:
Thanks Richard, I will use text from now on. Sorry for the inconvenience. I didn't even notice with Thunderbird since I had the display HTML as plain text option selected. -- 73, Cecil http://www.w5dxp.com |
Loading Coils; was : Vincent antenna
Cecil Moore wrote:
... I didn't even notice with Thunderbird since I had the display HTML as plain text option selected. That's because you have good taste and Thunderbird ROCKS! (the newsreader, NOT the wine ;-) ) Regards, JS |
Loading Coils; was : Vincent antenna
On Thu, 13 Dec 2007 08:40:53 -0800, Roger wrote:
And just for completeness... The fundamental equations also work when: - the signal is not sinusoidal, e.g. pulse, step, square, ... - rather than a load at one end, there is a source at each end - the sources at each end produce different arbitrary functions - the arbitrary functions at each end are DC sources It is highly instructive to compute the forward and reverse voltage and current (and then power) for a line with the same DC voltage applied to each end. ...Keith ...Keith Interesting! The important thing is to get answers that agree with our experiments. I have done some computations for DC voltage applied to transmission lines. The real surprise for me came when I realized that transmission line impedance could be expressed as a function of capacitance and the wave velocity. Z0 = 1/cC where c is the velocity of the wave and C is the capacitance of the transmission line per unit length. Hi Roger, This last round has piqued my interest when we dipped into DC. Those "formulas" would lead us to a DC wave velocity? 73's Richard Clark, KB7QHC |
Loading Coils; was : Vincent antenna
Cecil Moore wrote:
Keith Dysart wrote: Can you expand on the two different interpretations of "transfer" that will bring these views into alignment? Perhaps you really are disagreeing on whether EM waves always transfer energy (using the common definition of "transfer"). Jim refuses to provide a reference for his definition of "transfer". As I have said before, I am using whatever definition is used, for example, by Haliday and Resnick when they talk about power. I am not able to inquire as to what exact definition they use. All I know is when you say that energy is "transferring" in a transmission line, and then try to use that statement as proof that "power is moving" in a transmission line, you have the wrong idea about transfer of energy. That is precisely where this discussion originated, but I'm sure that you will disagree - as it is your nature to be highly disagreeable on this subject. ac6xg |
Loading Coils; was : Vincent antenna
Jim Kelley wrote:
aAll I know is when you say that energy is "transferring" in a transmission line, and then try to use that statement as proof that "power is moving" in a transmission line, you have the wrong idea about transfer of energy. I recently tried, on this newsgroup, to explain to Richard Harrison that power does *NOT* move in a transmission line. Richard thinks that power does move as do most of my engineering textbooks and the IEEE. Johnson, Ramo, and Whinnery all talk about "power flow". Because it was hairlipping you, I removed any reference to "power flow" from my magazine article in support of your concept that power does not flow. I have *NEVER* said "power is moving", at least not in this century. That is just your straw man raising its ugly head yet once again. Jim, when you force yourself to bear false witness about what I have said, you are essentially giving up whatever integrity and ethics you ever had. Why you have to resort to such underhanded unfair techniques speaks volumes. -- 73, Cecil http://www.w5dxp.com |
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