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Can you solve this 2?
The first example was much too easy. How about this one?
---50 ohm feedline---+---300 ohm feedline--- Pfwd1=100w-- Pfwd2 not given-- --Pref1=0w --Pref2 not given Given a Z0-match at point '+': Solve for Vfwd1, Ifwd1, Vref1, Iref1, Pfwd2, Vfwd2, Ifwd2, Pref2, Vref2, Iref2, including magnitudes and phase angles for all voltages and currents. Source is unknown. Load is unknown. Lengths of feedlines are unknown. Who thinks this one is impossible to solve? -- 73, Cecil http://www.qsl.net/w5dxp ----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 100,000 Newsgroups ---= East/West-Coast Server Farms - Total Privacy via Encryption =--- |
Just hook it up and see if it works.
If not, change one the "thingys" and try again. Repeat until it works. end loop "Cecil Moore" wrote in message ... The first example was much too easy. How about this one? ---50 ohm feedline---+---300 ohm feedline--- Pfwd1=100w-- Pfwd2 not given-- --Pref1=0w --Pref2 not given Given a Z0-match at point '+': Solve for Vfwd1, Ifwd1, Vref1, Iref1, Pfwd2, Vfwd2, Ifwd2, Pref2, Vref2, Iref2, including magnitudes and phase angles for all voltages and currents. Source is unknown. Load is unknown. Lengths of feedlines are unknown. Who thinks this one is impossible to solve? -- 73, Cecil http://www.qsl.net/w5dxp ----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 100,000 Newsgroups ---= East/West-Coast Server Farms - Total Privacy via Encryption =--- |
Hal:
Could you explain that in less technical terms? John "Hal Rosser" wrote in message ... Just hook it up and see if it works. If not, change one the "thingys" and try again. Repeat until it works. end loop "Cecil Moore" wrote in message ... The first example was much too easy. How about this one? ---50 ohm feedline---+---300 ohm feedline--- Pfwd1=100w-- Pfwd2 not given-- --Pref1=0w --Pref2 not given Given a Z0-match at point '+': Solve for Vfwd1, Ifwd1, Vref1, Iref1, Pfwd2, Vfwd2, Ifwd2, Pref2, Vref2, Iref2, including magnitudes and phase angles for all voltages and currents. Source is unknown. Load is unknown. Lengths of feedlines are unknown. Who thinks this one is impossible to solve? -- 73, Cecil http://www.qsl.net/w5dxp ----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 100,000 Newsgroups ---= East/West-Coast Server Farms - Total Privacy via Encryption =--- |
Cecil Moore wrote:
The first example was much too easy. How about this one? ---50 ohm feedline---+---300 ohm feedline--- Pfwd1=100w-- Pfwd2 not given-- --Pref1=0w --Pref2 not given Given a Z0-match at point '+': Solve for Vfwd1, Ifwd1, Vref1, Iref1, Pfwd2, Vfwd2, Ifwd2, Pref2, Vref2, Iref2, including magnitudes and phase angles for all voltages and currents. Source is unknown. Load is unknown. Lengths of feedlines are unknown. Who thinks this one is impossible to solve? I just received an email from someone who solved it. Now who says an energy analysis is impossible or meaningless? -- 73, Cecil http://www.qsl.net/w5dxp ----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 100,000 Newsgroups ---= East/West-Coast Server Farms - Total Privacy via Encryption =--- |
On Sat, 02 Jul 2005 08:21:07 -0500, Cecil Moore
wrote: The first example was much too easy. How about this one? ---50 ohm feedline---+---300 ohm feedline--- Pfwd1=100w-- Pfwd2 not given-- --Pref1=0w --Pref2 not given Given a Z0-match at point '+': Solve for Vfwd1, Ifwd1, Vref1, Iref1, Pfwd2, Vfwd2, Ifwd2, Pref2, Vref2, Iref2, including magnitudes and phase angles for all voltages and currents. Source is unknown. Load is unknown. Lengths of feedlines are unknown. Without disclosing the answers or the exact procedure for solving the "brain teaser", I would like to draw attention to some of the implicit relationships that "ought" to help. 1) It is assumed that both feelines have purely resistive characteristic impedances (imaginary component, Xo, is zero). 2) Regardless of the length of the 300 ohm line and its termination impedance, the standing wave pattern and the voltages and currents, both incident and reflected as a function of distance x along that line are determined completely by the requirement/condition that there is a Z0 match at point "+". 3) There are an infinite number of lengths of the 300 ohm line and a corresponding infinite number of termination impedances for that line that will produce a Z0 match at point "+". However, because of (2), above, some of those combinations are well known combinations with well understood results (e.g., odd multiple of quarter wavelength or an integer number of half wavelengths). 4) Due to conditions (1) and (2) above, the phase relations between all of the voltages and currents immediately adjacent to either side of point "+" are trivial (i.e., any two quantities chosen will be either exactly in phase or exactly 180 degrees out of phase with one another). Due to (3) and (4) above, it would seem that an arbitrary choice of either a quarter wave line with an 1800 ohm termination or a half wave line with a 50 ohm termination would provide a convenient example with which to begin an analysis. However, that is not necessary and only provides a crutch to get off dead center. If all of the above elements are kept in mind, then it becomes a matter of solving a simple algebraic relationship involving 4 equations with 4 unknowns (the incident and reflected voltages and currents at the right hand side of point "+"). The actual numerical answer to such a problem is irrelevant. The points to be learned from all this are really the implicit relationships (2), (3) and (4) above. Without an understanding of those points, it is virtually impossible to even know where to start. I think that is the real point that Cecil is trying to make. Bob, W9DMK, Dahlgren, VA Replace "nobody" with my callsign for e-mail http://www.qsl.net/w9dmk http://zaffora/f2o.org/W9DMK/W9dmk.html |
W9DMK (Robert Lay) wrote:
The actual numerical answer to such a problem is irrelevant. The points to be learned from all this are really the implicit relationships (2), (3) and (4) above. Without an understanding of those points, it is virtually impossible to even know where to start. I think that is the real point that Cecil is trying to make. Actually, it is one mm broader than that. In the above analysis, an energy analysis works just as well as any other, contrary to the Sacred Cow Lamentations I and II of some experts on this newsgroup. There is so much redundancy built into the voltage, current, and power relationships in a transmission line that there are a number of valid ways to skin the cat. An energy analysis is one of those valid ways. Two people have sent me emails with correct solutions. Here's how to approach the solution from an energy standpoint. ---50 ohm feedline---+---300 ohm feedline--- Pfwd1=100w-- Pfwd2 not given-- --Pref1=0w --Pref2 not given rho=250/350=0.7143, rho^2 = 0.51, (1-rho^2) = 0.49 rho^2 is the power reflection coefficient. (1-rho^2) is the power transmission coefficient. Pfwd1*rho^2 = 100*0.51 = 51w reflected back toward the source at the match point. My article labels that quantity 'P3' Pfwd1*(1-rho^2) = 100*0.49 = 49 watts transmitted through the match point toward the load. My article labels that quantity 'P1' (as does Dr. Best's QEX article). For a match to exist Pref2(1-rho^2) must equal 51w, the part of Pref2 transmitted back through the match point, i.e. not re-reflected. My article labels that quantity 'P4' That makes Pref2 = 51w/0.49 = 104.1w, and makes Pref2(rho^2) = 53.1w, the part initially re-reflected. My article labels that quantity 'P2' as does Dr. Best's QEX article. So Pfwd2 = P1 + P2 + P3 + P4 = 49w + 53.1w + 51w + 51w = 204.1w Who said powers can never be added? Pfwd2 is indeed 204.1w. Now that we know all the powers (without knowing a single voltage) we can calculate the voltages and currents whose phase angles are all either zero degrees or 180 degrees. As Bob sez, phase angles are trivial at a Z0-match point. Is there anybody out there who still believes that an energy analysis is impossible and/or "gobbledegook"? Incidentally, the two 51w component powers represent the amount of destructive interference energy involved in wave cancellation and the amount of constructive interference energy re-reflected toward the load as a result of that wave cancellation. This is something that Dr. Best completely missed in his QEX article. He correctly identified P1 and P2 but completely ignored P3 and P4. Thus he came up with the equation: Ptot = 75w + 8.33w = 133.33w. Remember that argument on this newsgroup from spring of 2001? -- 73, Cecil http://www.qsl.net/w5dxp ----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 100,000 Newsgroups ---= East/West-Coast Server Farms - Total Privacy via Encryption =--- |
I would have used the term "Whatchacallit", but "thingy" seems to work.
"John Smith" wrote in message ... Hal: Could you explain that in less technical terms? John "Hal Rosser" wrote in message ... Just hook it up and see if it works. If not, change one the "thingys" and try again. Repeat until it works. end loop "Cecil Moore" wrote in message ... The first example was much too easy. How about this one? ---50 ohm feedline---+---300 ohm feedline--- Pfwd1=100w-- Pfwd2 not given-- --Pref1=0w --Pref2 not given Given a Z0-match at point '+': Solve for Vfwd1, Ifwd1, Vref1, Iref1, Pfwd2, Vfwd2, Ifwd2, Pref2, Vref2, Iref2, including magnitudes and phase angles for all voltages and currents. Source is unknown. Load is unknown. Lengths of feedlines are unknown. Who thinks this one is impossible to solve? -- 73, Cecil http://www.qsl.net/w5dxp ----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 100,000 Newsgroups ---= East/West-Coast Server Farms - Total Privacy via Encryption =--- |
W9DMK (Robert Lay) wrote:
On Sat, 02 Jul 2005 08:21:07 -0500, Cecil Moore wrote: The first example was much too easy. How about this one? ---50 ohm feedline---+---300 ohm feedline--- Pfwd1=100w-- Pfwd2 not given-- --Pref1=0w --Pref2 not given Given a Z0-match at point '+': Solve for Vfwd1, Ifwd1, Vref1, Iref1, Pfwd2, Vfwd2, Ifwd2, Pref2, Vref2, Iref2, including magnitudes and phase angles for all voltages and currents. Source is unknown. Load is unknown. Lengths of feedlines are unknown. Without disclosing the answers or the exact procedure for solving the "brain teaser", I would like to draw attention to some of the implicit relationships that "ought" to help. 1) It is assumed that both feelines have purely resistive characteristic impedances (imaginary component, Xo, is zero). 2) Regardless of the length of the 300 ohm line and its termination impedance, the standing wave pattern and the voltages and currents, both incident and reflected as a function of distance x along that line are determined completely by the requirement/condition that there is a Z0 match at point "+". 3) There are an infinite number of lengths of the 300 ohm line and a corresponding infinite number of termination impedances for that line that will produce a Z0 match at point "+". However, because of (2), above, some of those combinations are well known combinations with well understood results (e.g., odd multiple of quarter wavelength or an integer number of half wavelengths). 4) Due to conditions (1) and (2) above, the phase relations between all of the voltages and currents immediately adjacent to either side of point "+" are trivial (i.e., any two quantities chosen will be either exactly in phase or exactly 180 degrees out of phase with one another). Due to (3) and (4) above, it would seem that an arbitrary choice of either a quarter wave line with an 1800 ohm termination or a half wave line with a 50 ohm termination would provide a convenient example with which to begin an analysis. However, that is not necessary and only provides a crutch to get off dead center. If all of the above elements are kept in mind, then it becomes a matter of solving a simple algebraic relationship involving 4 equations with 4 unknowns (the incident and reflected voltages and currents at the right hand side of point "+"). The actual numerical answer to such a problem is irrelevant. The points to be learned from all this are really the implicit relationships (2), (3) and (4) above. Without an understanding of those points, it is virtually impossible to even know where to start. I think that is the real point that Cecil is trying to make. Bob, W9DMK, Dahlgren, VA Replace "nobody" with my callsign for e-mail http://www.qsl.net/w9dmk http://zaffora/f2o.org/W9DMK/W9dmk.html Cecil already defined the voltage and current at the match point when he gave the characteristic impedances of the two lines and the rate of energy transfer through them. Knowing the voltage and current, anyone can calculate Pfwd2 and Prev2 using Pfwd2 = |(V+IZ0)/2sqrt(Z0)|^2 and Prev = |(V-IZ0)/2sqrt(Z0)|^2, where Z0 is the characteristic impedance of the second transmission line. Cecil's ability to add powers together, which he did in this instance, isn't anything unique, and doesn't really teach anything about the general case. In fact, for a quarter wave transformer, you can do the following trick: compute the value of the power as it just comes through the impedance discontinuity for the first time and call it Pa. Call Rho^2 at the load P. Then the power delivered to the load will be Pa( 1 + P + P^2 + P^3 + P^4 ....) which looks the same as if the power reflection coefficient looking back toward the generator was 1 and the power at the load was the result of the addition of an infinite number of reflections. Such an interpretation, though, can be shown to be absolutely wrong. Can anyone see why? 73, Tom Donaly, KA6RUH |
Tom Donaly wrote:
Cecil's ability to add powers together, which he did in this instance, isn't anything unique, and doesn't really teach anything about the general case. I'm glad you agree, Tom. Other experts on this newsgroup will argue with you as they have with me for four years ever since Dr. Best posted his infamous Z0-match equation: Ptot = 75w + 8.33w = 133.33w to which I objected back then, only to have most of the rest of the posters agree with Dr. Best. I was dumbfounded to see so many otherwise knowledgable engineers agree to a violation of the principle of conservation of energy. I was told not to worry about conservation of energy - that it takes care of itself. In fact, for a quarter wave transformer, you can do the following trick: compute the value of the power as it just comes through the impedance discontinuity for the first time and call it Pa. Call Rho^2 at the load P. Then the power delivered to the load will be Pa( 1 + P + P^2 + P^3 + P^4 ....) which looks the same as if the power reflection coefficient looking back toward the generator was 1 and the power at the load was the result of the addition of an infinite number of reflections. Such an interpretation, though, can be shown to be absolutely wrong. Can anyone see why? Destructive interference between the external reflection at the match point and the internal reflection from the load supplies additional constructive interference energy to the forward wave in the quarter wave transformer. You didn't include that constructive interference energy above. Hint: That virtual power reflection coefficient looking rearward into the match point doesn't reach 1 until steady- state is reached (wrong premise above). The virtual power reflection coefficient looking forward into the match point also doesn't reach 0 until steady-state is reached. Those two virtual power reflection coefficients actually start out the same value and proceed in opposite directions during the transient buildup to steady-state. -- 73, Cecil http://www.qsl.net/w5dxp ----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 100,000 Newsgroups ---= East/West-Coast Server Farms - Total Privacy via Encryption =--- |
Cecil Moore wrote:
Tom Donaly wrote: Cecil's ability to add powers together, which he did in this instance, isn't anything unique, and doesn't really teach anything about the general case. I'm glad you agree, Tom. Other experts on this newsgroup will argue with you as they have with me for four years ever since Dr. Best posted his infamous Z0-match equation: Ptot = 75w + 8.33w = 133.33w to which I objected back then, only to have most of the rest of the posters agree with Dr. Best. I was dumbfounded to see so many otherwise knowledgable engineers agree to a violation of the principle of conservation of energy. I was told not to worry about conservation of energy - that it takes care of itself. In fact, for a quarter wave transformer, you can do the following trick: compute the value of the power as it just comes through the impedance discontinuity for the first time and call it Pa. Call Rho^2 at the load P. Then the power delivered to the load will be Pa( 1 + P + P^2 + P^3 + P^4 ....) which looks the same as if the power reflection coefficient looking back toward the generator was 1 and the power at the load was the result of the addition of an infinite number of reflections. Such an interpretation, though, can be shown to be absolutely wrong. Can anyone see why? Destructive interference between the external reflection at the match point and the internal reflection from the load supplies additional constructive interference energy to the forward wave in the quarter wave transformer. You didn't include that constructive interference energy above. Hint: That virtual power reflection coefficient looking rearward into the match point doesn't reach 1 until steady- state is reached (wrong premise above). The virtual power reflection coefficient looking forward into the match point also doesn't reach 0 until steady-state is reached. Those two virtual power reflection coefficients actually start out the same value and proceed in opposite directions during the transient buildup to steady-state. Hi Cecil, you come up with the right answer, but is your interpretation correct? Can you do the same thing in a general sense? If there is no Z0 match between the two transmission lines, does your method still work? The little conundrum I posed is an example of a procedure that will actually give the right answer, but the interpretation I gave of how it works is wrong. Can you be sure your method doesn't have the same flaw? 73, Tom Donaly, KA6RUH (P.S. The method of using V and I and the junction of the two xmission lines to find the forward and reverse powers on a transmission line doesn't prove the powers exist. It works just as easily with a pair of resistors and is more an algebraic stunt that works than anything else. It does agree with you, however.) |
Tom Donaly wrote:
you come up with the right answer, but is your interpretation correct? Can you do the same thing in a general sense? If there is no Z0 match between the two transmission lines, does your method still work? As a stand alone analysis, it yields two possible solutions but the purpose of this discussion is not to come up with a new stand alone method of analysis. The purpose is, given a standard analysis, to add TRACKING OF THE ENERGY COMPONENTS through an impedance discontinuity, something many people believe to be impossible. It wasn't designed to work as a stand alone analysis but it does for Z0-matched systems, the most usual ham configuration. However, an additional piece of information is required in the general case to be able to tell which voltage is leading and which is lagging. (P.S. The method of using V and I and the junction of the two xmission lines to find the forward and reverse powers on a transmission line doesn't prove the powers exist. Do you think the powers defined in HP App Note 95-1 exist? Remember my one second long transmission line example where the number of stored joules exactly equaled the number of joules required by the forward wave and the reflected wave? If the energy is not in those waves, where is it? Nobody has provided any explaination of how standing waves can exist without forward and reflected waves. Under "standing wave", The IEEE Dictionary says: "A pure standing wave results from the interference of two oppositely directed traveling waves of the same frequency and amplitude." i.e. standing waves are the result (effect), two oppositely directed traveling waves are the *cause*. Most of my references agree. The forward and reflected wave energy components must exist as causes before standing waves can materialize as an effect. -- 73, Cecil http://www.qsl.net/w5dxp ----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 100,000 Newsgroups ---= East/West-Coast Server Farms - Total Privacy via Encryption =--- |
Cecil Moore wrote:
Who said powers can never be added? Must have been someone who was unfamiliar with the expression 'figures can lie and liars can figure'. :-) ac6xg |
Jim Kelley wrote:
Cecil Moore wrote: Who said powers can never be added? Must have been someone who was unfamiliar with the expression 'figures can lie and liars can figure'. :-) You reckon Eugene Hecht was lying when he shows us how to add two irradiances to obtain the total irradiance (power per unit-area) in _Optics_? Adding EM wave powers during interference is a well accepted way of handling EM wave superposition in the field of optics. The bright constructive interference rings contain more power than the dark destructive interference rings. RF waves and light waves are both electro- magnetic waves, just at different frequencies. Asserting that RF waves obey a different set of laws of physics than do light waves is naive ignorance at best. -- 73, Cecil http://www.qsl.net/w5dxp ----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 120,000+ Newsgroups ----= East and West-Coast Server Farms - Total Privacy via Encryption =---- |
Cecil Moore wrote: Jim Kelley wrote: Cecil Moore wrote: Who said powers can never be added? Must have been someone who was unfamiliar with the expression 'figures can lie and liars can figure'. :-) You reckon Eugene Hecht was lying when he shows us how to add two irradiances to obtain the total irradiance (power per unit-area) in _Optics_? Eugene Hecht doesn't have a dog in this fight, Cecil. But the quote is a truism that applies in any case. Wrong numbers added correctly produce a wrong number; correct numbers added incorrectly produce an incorrect number; and in the special case, certain wrong numbers added in a particular incorrect way can produce a desired result. You take too great a liberty with the name Eugene Hecht. Among the things which won't be found in any of Dr. Hecht's texts is a minus sign in front of number expressing an irradiance. Nor will we find a negative scalar quantity accompanied by the claim that the negative sign indicates a change in direction, as you have done. Eugene Hecht also did not claim that interference could be a cause for energy to reflect or otherwise change direction, as you have done. Such claims are blatently false. Power and irradiance are derived and dependent quantities, not fundamental independent quantities in nature. And although an automobile moves at some speed, the scaler quantity itself is not something which moves. Similarly, power and irradiance do not physically propagate and they do not physically interact. 'They' do not reflect, refract, diffract, disperse, interfere, or act upon other 'powers' or 'irradiances'. JC Maxwell and others observed that it is electric and magnetic fields which propagate, interact with matter, and add algebraically and vectorially. When fields physically interact with matter, we can measure their effect and can quantify such things as voltage, current, and heat, and hence calculate such things as power or irradiance. But it is actually the fields themselves which algebraically sum. Of course the interference equation accurately expresses power and irradiance. The fact that power and irradiance generally go as the square of the fields allows us to correctly make certain additional mathematical assumptions. One must still be careful not to mistake an effect for a cause. But it is the 2nd Amendment, the internet, and the absence of peer review which afford men the freedom and means to work equations and describe physical phenomena in any way they like. 73, ac6xg |
Jim Kelley wrote:
Jim, you have a habit of erecting strawmen somewhat like: "I don't care what you say, the sun will rise tomorrow." For that reason, I'm going to trim the parts of your posting with which I agree and have never disagreed. You take too great a liberty with the name Eugene Hecht. Among the things which won't be found in any of Dr. Hecht's texts is a minus sign in front of number expressing an irradiance. Sure wish you would read the book before making such statements. On the contrary, here's equation (9.16) representing total destructive interference. Imin = I1 + I2 - 2*SQRT(I1*I2) = 0 The third term is indeed a minus sign in front of a number expressing irradiance. However, total average irradiance cannot be less than zero. And for the record, I have never said total average power could be less than zero but, like Hecht, I treat destructive interference energy as a negative term and constructive interference energy as a positive term. Dr. Stephen Best, VE9SRB, did the same thing for his "Wave Mechanics of Transmission Lines, Part 3:" QEX article, Nov/Dec 2001. He said: "When the voltages V1 and V2 are exactly 180 deg out of phase, the total power can be determined as follows:" "PFtotal = P1 + P2 - 2*SQRT(P1)*SQRT(P2)" so if you don't like negative power terms, you should confront both Eugene Hecht and Dr. Best. Nor will we find a negative scalar quantity accompanied by the claim that the negative sign indicates a change in direction, as you have done. On the contrary, in equation 9.16 above, according to Hecht, the interference term is negative indicating "total destructive interference", his words, not mine. Here's Hecht's quote from _Optics_. “The principle of conservation of energy makes it clear that if there is constructive interference at one point, the ‘extra’ energy at that location must have come from somewhere else. There must therefore be destructive interference somewhere else." Sorry, but a negative interference term denotes destructive interference. A positive interference term denotes constructive interference. In a transmission line with only two directions, if destructive interference occurs in one direction, then constructive interference must occur in the only other direction in order to satisfy the conservation of energy principle. A wave cancellation event in a transmission line implies an equal constructive interference event in the opposite direction. Anything else violates the laws of physics. Similarly, power and irradiance do not physically propagate and they do not physically interact. On the contrary, they do physically interact for coherent waves as can be inferred by the interference equations. Please reference Chapter 9 in _Optics_, by Hecht. The mathematical interaction of power and irradiance is a *result* of superposition of coherent EM waves. That's where the interference equations involving irradiance come from. JC Maxwell and others observed that it is electric and magnetic fields which propagate, interact with matter, and add algebraically and vectorially. And contain power equal to ExH. EM waves cannot exist without energy. If EM waves interact, their energy components interact. Destructive and constructive interference cannot occur without energy components which follow the laws of physics. Of course the interference equation accurately expresses power and irradiance. That is some progress on your part so there's hope. What you need to realize is that those interference equations define what happens to the energy at a match point in a transmission line. Dr. Best kicked this discussion off by his QEX article. He just didn't realize that the equations he published were virtually identical to the classical optical interference equations. -- 73, Cecil http://www.qsl.net/w5dxp ----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 100,000 Newsgroups ---= East/West-Coast Server Farms - Total Privacy via Encryption =--- |
On Tue, 12 Jul 2005 22:48:00 -0500, Cecil Moore
wrote: Nor will we find a negative scalar quantity accompanied by the claim that the negative sign indicates a change in direction, as you have done. On the contrary, in equation 9.16 above, according to Hecht, the interference term is negative indicating "total destructive interference", his words, not mine. Here's Hecht's quote from _Optics_. [Hecht rolls his eyes] Jim's point is won, absolutely nothing quoted here explicitly states a change in direction. That is, as Jim points out, the math follows the physics, it does not create the physics. There is a vast gulf between being descriptive and being proscriptive. |
Richard Clark wrote:
[Hecht rolls his eyes] I'm going to trim and ignore the condescending ad hominem stuff. ... the math follows the physics, it does not create the physics. Your argument has that exact flaw. "What Cecil is describing doesn't exist in the common math model. Therefore, the math model prohibits it from existing in physics." Please follow your own advice. There is a vast gulf between being descriptive and being prohibitive. There is a vast gulf between being descriptive and being proscriptive. I didn't choose to quote the entire book, Richard. Hecht also says: "If two or more electromagnetic waves arrive at point P out-of-phase and cancel, 'What does that mean as far as their energy is concerned?' Energy can be distributed, but it doesn’t cancel out. ... The superposition of coherent waves generally has the effect of altering the spatial distribution of the energy but not the total amount (of energy) present." "Altering the spatial distribution of the energy" in a transmission line is a binary function since there are only two directions. If the spatial distribution is altered, it necessarily changes directions. The following does explicitly state a change in direction, i.e. "A NEW DIRECTION". http://micro.magnet.fsu.edu/primer/j...ons/index.html "When two waves of equal amplitude and wavelength that are 180-degrees out of phase with each other meet, they are not actually annihilated. All of the photon energy present in these waves must somehow be recovered or REDISTRIBUTED IN A NEW DIRECTION, according to the law of energy conservation ... Instead, upon meeting, the photons are redistributed to regions that permit constructive interference, so the effect should be considered as a redistribution of light waves and photon energy rather than the spontaneous construction or destruction of light." (Emphasis mine.) A transmission line has only two directions. If wave cancellation, i.e. permanent destructive interference, takes place in one direction, the necessary corresponding constructive interference must be "redistributed in a new direction". In a transmission line, there is only one "new direction", the opposite direction from the old direction. -- 73, Cecil http://www.qsl.net/w5dxp ----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 120,000+ Newsgroups ----= East and West-Coast Server Farms - Total Privacy via Encryption =---- |
On Wed, 13 Jul 2005 07:28:21 -0500, Cecil Moore
wrote: There is a vast gulf between being descriptive and being proscriptive. I didn't choose to quote the entire book [Hecht rolls his eyes] That would have been futile because no portion of it contains the proscription. What has been offered makes as much sense as ascribing the value of $100 to a button simply because you sewed it to a jacket and found $100 in the pocket of that jacket. -Superstition- |
Cecil Moore wrote:
"PFtotal = P1 + P2 - 2*SQRT(P1)*SQRT(P2)" so if you don't like negative power terms, you should confront both Eugene Hecht and Dr. Best. Don't be foolish. Obviously neither of the P terms can be negative if PFtotal is supposed to represent a real number. I have no issues to confront with either of the gentlemen. It is where you diverge from Hecht (and Maxwell, and Born and Wolfe, and Jackson) that I take issue. Nor will we find a negative scalar quantity accompanied by the claim that the negative sign indicates a change in direction, as you have done. On the contrary, in equation 9.16 above, according to Hecht, the interference term is negative indicating "total destructive interference", his words, not mine. Here's Hecht's quote from _Optics_. One statement does not contradict the other, as the subject in each sentence is entirely different. Both statements are obviously true. Similarly, power and irradiance do not physically propagate and they do not physically interact. On the contrary, they do physically interact for coherent waves as can be inferred by the interference equations. Please reference Chapter 9 in _Optics_, by Hecht. The mathematical interaction of power and irradiance is a *result* of superposition of coherent EM waves. That's where the interference equations involving irradiance come from. As I explained they come from the fact that the fields interact, and that power and intensity (or irradiance) go as the square of the field. Lets say the square of F1 (field 1) is proportional with P1, and the square of F2 is proportional with P2. And lets say the mathematical description of the way the two fields interact is as follows: Ftotal = (F1 - F2)*(F1 - F2). (Looks kinda like modulation, but I digress.) We can then write that as Ftotal = F1^2 + F2^2 - 2*F1*F2. By substitution then, PFtotal = P1 + P2 - 2*SQRT(P1*P2). And that's where your favorite equation comes from. 73, ac6xg |
Jim Kelley wrote:
It is where you diverge from Hecht (and Maxwell, and Born and Wolfe, and Jackson) that I take issue. I don't diverge from them, Jim. I have simply tied a few loose ends together using logical deduction based on the laws of physics. So far, you have produced zero instances where I diverge from the laws of physics. OTOH, you appear to have diverged quite often, e.g. Maxwell's equations prove that standing waves can exist without a rearward-traveling wave, cancelled waves don't contain energy or momentum before they are cancelled, reflected waves are not re- reflected by wave cancellation, there is no before and after, etc. PFtotal = P1 + P2 - 2*SQRT(P1*P2). And that's where your favorite equation comes from. I have said all along that energy cannot be separated from the waves containing the energy and that's why an energy analysis is possible. -- 73, Cecil http://www.qsl.net/w5dxp ----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 100,000 Newsgroups ---= East/West-Coast Server Farms - Total Privacy via Encryption =--- |
Cecil Moore wrote: Jim Kelley wrote: It is where you diverge from Hecht (and Maxwell, and Born and Wolfe, and Jackson) that I take issue. I don't diverge from them, Jim. I have simply tied a few loose ends together using logical deduction based on the laws of physics. Yes, Richard described that process pretty accurately I thought. So far, you have produced zero instances where I diverge from the laws of physics. I produced three just yesterday. OTOH, you appear to have diverged quite often, e.g. Maxwell's equations prove that standing waves can exist without a rearward-traveling wave, cancelled waves don't contain energy or momentum before they are cancelled, reflected waves are not re- reflected by wave cancellation, there is no before and after, etc. Please provide exact quotes. Otherwise, you're taking liberties with the truth. I have said all along that energy cannot be separated from the waves containing the energy and that's why an energy analysis is possible. Yes you have said that, whatever it means. Born and Wolf has an interesting comment in the section on total reflection. "...the electromagnetic field in the second medium does not disappear, only there is no longer a flow of energy across the boundary." 73, ac6xg |
Jim Kelley wrote:
Cecil Moore wrote: So far, you have produced zero instances where I diverge from the laws of physics. I produced three just yesterday. Most of your past objections are personal opinions that have been based on a lack of understanding of what I was saying. Please list just one law of physics from which I have diverged. I do not think you can do that. -- 73, Cecil http://www.qsl.net/w5dxp ----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 100,000 Newsgroups ---= East/West-Coast Server Farms - Total Privacy via Encryption =--- |
On Wed, 13 Jul 2005 22:34:58 -0500, Cecil Moore
wrote: Most of your past objections are personal opinions Curious how you flail at these imaginary demons and blow off his actual quote from your source negating your premise. How you continually fail to stand by your own citations has lost its novelty. |
Cecil Moore wrote:
Most of your past objections are personal opinions that have been based on a lack of understanding of what I was saying. It is my opinion that most of my past objections were based on your lack of understanding of what you were saying. ;-) Please list just one law of physics from which I have diverged. I do not think you can do that. Physics doesn't have a book of code violations, Cecil. It's more like a big set of equations. The rules are mathematical. I've already shown you where you made mistakes. What tortuous obligation have I encumbered that dooms me to an eternity of repeating these things to you? Just try turning down the squelch a little. 73, ac6xg |
Jim Kelley wrote:
I've already shown you where you made mistakes. What you have shown me are a bunch of strawmen with which I have no arguments. As a result, I have no idea upon what we disagree. Most of your technical assertions are true and I agree with them. When you derived the same total destructive interference equation that I had been posting, including the negative power term, virtually all of our arguments went away. How about technically explaining in detail just one mistake you think I have made? I need to understand a mistake before I can correct it. Here's a typical objection of yours, an implication with no technical content. It is where you diverge from Hecht ... that I take issue. I sincerely have no idea where you think I diverge from Hecht and your refusal to enlighten me is interesting. In fact, I have quoted Hecht extensively and borrowed some of his concepts from optics to apply to RF. His treatments of superposition and interference are the best I have ever read. I am not aware of any divergence from Hecht on my part. Your assertion that I diverge from Hecht or Richard presuming to roll Hecht's eyes for him contains zero technical content from which I learn nothing. -- 73, Cecil http://www.qsl.net/w5dxp ----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 120,000+ Newsgroups ----= East and West-Coast Server Farms - Total Privacy via Encryption =---- |
On Thu, 14 Jul 2005 22:56:19 -0500, Cecil Moore
wrote: Your assertion that I diverge from Hecht or Richard presuming to roll Hecht's eyes for him contains zero technical content from which I learn nothing. Amusing, when I quote Hecht, it is presumption, when you quote Hecht, it is receiving tablets on Ararat. Well it beats your impersonation of Galileo. That's OK, no one expects you to respond to Jim's point drawn from Hecht. |
Richard Clark wrote:
Cecil Moore wrote: Your assertion that I diverge from Hecht or Richard presuming to roll Hecht's eyes for him contains zero technical content from which I learn nothing. Amusing, when I quote Hecht, it is presumption, ... I am not objecting to your quoting Hecht. I am objecting to you being presumptious enough to roll someone else's eyeballs. How do you know Hecht is not rolling his eyeballs at your postings? The only time I remember you quoting Hecht was with some irrelevant refraction stuff having nothing to do with transmission lines or with the perfect laser example. -- 73, Cecil http://www.qsl.net/w5dxp ----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 100,000 Newsgroups ---= East/West-Coast Server Farms - Total Privacy via Encryption =--- |
On Fri, 15 Jul 2005 07:03:00 -0500, Cecil Moore
wrote: having nothing to do with transmission lines or with the perfect laser example. What a hoot! Your sacred cows mew. |
Cecil Moore wrote:
Jim Kelley wrote: I've already shown you where you made mistakes. What you have shown me are a bunch of strawmen with which I have no arguments. As a result, I have no idea upon what we disagree. Most of your technical assertions are true and I agree with them. When you derived the same total destructive interference equation that I had been posting, including the negative power term, virtually all of our arguments went away. How about technically explaining in detail just one mistake you think I have made? I need to understand a mistake before I can correct it. Here's a typical objection of yours, an implication with no technical content. It is where you diverge from Hecht ... that I take issue. I sincerely have no idea where you think I diverge from Hecht and your refusal to enlighten me is interesting. In fact, I have quoted Hecht extensively and borrowed some of his concepts from optics to apply to RF. His treatments of superposition and interference are the best I have ever read. I am not aware of any divergence from Hecht on my part. Your assertion that I diverge from Hecht or Richard presuming to roll Hecht's eyes for him contains zero technical content from which I learn nothing. And that is a wonderful example of the rhetorical way to hold your hands over your ears and hum. :-) So when does the article appear in Phys. Rev? 73, ac6xg |
Jim Kelley wrote:
And that is a wonderful example of the rhetorical way to hold your hands over your ears and hum. :-) Please note the technical content of your posting. Once you derived the interference equations on your own, the physical implications are clear and you apparently cannot come up with a disagreement between us since my conclusions were based on those very physics energy equations that you derived from first principles. I am not aware of any further disagreement between us. You are welcome to discuss what you perceive as a disagreement either here or by email. To summarize: EM energy cannot travel at any speed except the speed of light, cannot exist without energy, and that energy must be conserved. If reflected energy doesn't reach the source, it must necessarily be flowing toward the load and therefore, must have been re-reflected (as Walter Maxwell has been saying for decades). Having only two directions in a transmission line makes it easy. If EM energy is not traveling in one direction, it has to be traveling in the only other direction available. So when does the article appear in Phys. Rev? No news is probably not good news. -- 73, Cecil http://www.qsl.net/w5dxp ----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 120,000+ Newsgroups ----= East and West-Coast Server Farms - Total Privacy via Encryption =---- |
On Fri, 15 Jul 2005 16:25:01 -0500, Cecil Moore
wrote: I am not aware of any further disagreement between us. so short a memory.... On Wed, 13 Jul 2005 18:46:45 -0700, Jim Kelley wrote: Born and Wolf has an interesting comment in the section on total reflection. "...the electromagnetic field in the second medium does not disappear, only there is no longer a flow of energy across the boundary." your source, and yet unable or unwilling to confront this single observation. |
Richard Clark wrote: On Fri, 15 Jul 2005 16:25:01 -0500, Cecil Moore wrote: I am not aware of any further disagreement between us. so short a memory.... On Wed, 13 Jul 2005 18:46:45 -0700, Jim Kelley wrote: Born and Wolf has an interesting comment in the section on total reflection. "...the electromagnetic field in the second medium does not disappear, only there is no longer a flow of energy across the boundary." your source, and yet unable or unwilling to confront this single observation. Apparently that would mean the waves aren't traveling at the speed of light and it would violate his "waves cannot exist without energy" law of physics, so therefore the book is wrong. Besides, as a reference, Hecht is far more maleable. ;-) 73, ac6xg |
On Fri, 15 Jul 2005 16:15:37 -0700, Jim Kelley
wrote: Born and Wolf has an interesting comment in the section on total reflection. "...the electromagnetic field in the second medium does not disappear, only there is no longer a flow of energy across the boundary." your source, and yet unable or unwilling to confront this single observation. Apparently that would mean the waves aren't traveling at the speed of light and it would violate his "waves cannot exist without energy" law of physics, so therefore the book is wrong. Besides, as a reference, Hecht is far more maleable. ;-) Hi Jim, It is far more reminiscent of his proof of total cancellation, if you accept that total allows for several percent of non-totality. Such vague indifference is like building the Golden Gate and finding a gap of 40 or 50 feet in the middle. "Who's gonna' mind a couple of percent? It spans the total bay, and THAT'S what counts!" We have a bridge builder that wouldn't cross that bridge if he came to it. 73's Richard Clark, KB7QHC |
Richard Clark wrote:
Jim Kelley wrote: Born and Wolf has an interesting comment in the section on total reflection. "...the electromagnetic field in the second medium does not disappear, only there is no longer a flow of energy across the boundary." your source, and yet unable or unwilling to confront this single observation. Since the EM energy doesn't flow across the match point boundary toward the source, it must be redistributed in other directions. In a transmission line, there is only one other direction, i.e. the reflected energy is re-reflected at the match point. Wave cancellation in a transmission line redistributes the energy in the opposite direction as constructive interference. -- 73, Cecil http://www.qsl.net/w5dxp ----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 100,000 Newsgroups ---= East/West-Coast Server Farms - Total Privacy via Encryption =--- |
Jim Kelley wrote:
Richard Clark wrote: Jim Kelley wrote: Born and Wolf has an interesting comment in the section on total reflection. "...the electromagnetic field in the second medium does not disappear, only there is no longer a flow of energy across the boundary." your source, and yet unable or unwilling to confront this single observation. Apparently that would mean the waves aren't traveling at the speed of light and it would violate his "waves cannot exist without energy" law of physics, so therefore the book is wrong. Wrong. All it means is that reflected energy doesn't make it across the match point. Seems I read that in _Reflections_ a quarter century ago. Reflected energy traveling at the speed of light is re-reflected at the speed of light in the opposite direction. Wave cancellation accomplishes that feat. Regarding wave cancellation: http://micro.magnet.fsu.edu/primer/j...ons/index.html "... when two waves of equal amplitude and wavelength that are 180-degrees out of phase with each other meet, they are (canceled but) not actually annihilated. All of the photon energy present in these waves must somehow be recovered or redistributed in a new direction, according to the law of energy conservation. (There are only two directions available in a transmission line.) Instead, upon meeting, the photons are redistributed to regions that permit constructive interference, so the effect should be considered as a redistribution of light waves and photon energy (back toward the load) rather than the spontaneous construction or destruction of light." (Words in parentheses are mine added for clarity.) -- 73, Cecil http://www.qsl.net/w5dxp ----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 100,000 Newsgroups ---= East/West-Coast Server Farms - Total Privacy via Encryption =--- |
On Fri, 15 Jul 2005 22:27:25 -0500, Cecil Moore
wrote: "...the electromagnetic field in the second medium does not disappear, Wave cancellation in a transmission line redistributes the energy in the opposite direction as constructive interference. More imbalance in the balance equation passing as "totality." :-) It is established there is "some" amount of energy in the "second" medium (in other words, beyond the match point as I have demonstrated); it then follows there is not a total reflection (same demonstration), and certainly not as constructive (to what?) interference. |
Richard Clark wrote:
Cecil Moore wrote: Wave cancellation in a transmission line redistributes the energy in the opposite direction as constructive interference. It is established there is "some" amount of energy in the "second" medium (in other words, beyond the match point as I have demonstrated); it then follows there is not a total reflection (same demonstration), and certainly not as constructive (to what?) interference. What's wrong with this picture? Looking at it upside down? With the source on the left, the second medium is to the right (load side) of the first medium. Of course, there is energy to the right of the match point - because of standing waves, more energy than exists in the first medium to the left of the match point. There's no reflected energy in the first medium to the left of the match point. It appears to look something like my earlier example: 1w | 1/4WL | laser-----air-----|---thin-film---|---glass---... 1st medium | 2nd medium | 3rd medium n=1.0 n=1.2222 n=1.4938 Pfor=1w Pfor=1.0101w Pfor=1w Pref=0w Pref=0.0101w Pref=0w Reflected energy is eliminated at the air to thin-film interface because of wave cancellation (total destructive interference). According to Hecht and every other reference I've seen, the reflected energy involved in the wave cancellation event at the match point joins the forward wave in the 2nd medium. Of course, that increases the amount of energy in the 2nd medium beyond what exists in the 1st medium. The necessary (total constructive inter- ference) energy is contained in those standing waves in the 2nd medium. www.mellesgriot.com/products/optics/oc_2_1.htm "Clearly, if the wavelength of the incident light and the thickness of the film are such that a phase difference exists between reflections of p, then reflected wavefronts interfere destructively, and overall reflected intensity is a minimum. If the two reflections are of equal amplitude, then this amplitude (and hence intensity) minimum will be zero." [total destructive interference] "In the absence of absorption or scatter, the principle of conservation of energy indicates all 'lost' reflected intensity will appear as enhanced intensity [constructive interference energy] in the transmitted beam. The sum of the reflected and transmitted beam intensities is always equal to the incident intensity. This important fact has been confirmed experimentally." [my notes] In the above example, the laser's transmitted beam intensity is 1w. In the 2nd medium, the reflected beam intensity is 0.0101w. The incident intensity upon the 3rd medium is 1.0101w. "This important fact has been confirmed experimentally." The above example is equivalent to a matched 1/4WL transmission line section having the following lossless characteristics. 1w XMTR--50 ohm coax--+--1/4WL 61.2 ohm coax--+--75 ohm coax--75 ohm load Pfor=1w Pfor=1.0101w Pfor=1w Pref=0w Pref=0.0101w Pref=0w -- 73, Cecil http://www.qsl.net/w5dxp ----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 100,000 Newsgroups ---= East/West-Coast Server Farms - Total Privacy via Encryption =--- |
On Sat, 16 Jul 2005 07:52:23 -0500, Cecil Moore
wrote: What's wrong with this picture? Mewing sacred cows. You got it wrong the last time, it is the same this time, ex post facto it is still wrong. Whoring the names of references that you subsequently dismiss, deny or impeach hardly constitutes proof. |
Richard Clark wrote:
Cecil Moore wrote: What's wrong with this picture? Mewing sacred cows. You got it wrong the last time, it is the same this time, ex post facto it is still wrong. Whoring the names of references that you subsequently dismiss, deny or impeach hardly constitutes proof. Assertions with no proof - ad hominem attacks - physician, heal thyself. I furnished plenty of technical content. You furnished less than none. -- 73, Cecil http://www.qsl.net/w5dxp ----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 100,000 Newsgroups ---= East/West-Coast Server Farms - Total Privacy via Encryption =--- |
On Sat, 16 Jul 2005 12:20:32 -0500, Cecil Moore
wrote: You furnished less than none. Short memory in long supply. The complete treatment in math was offered successfully rebutting your proposition and you have shown nothing new. The negation stands. |
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