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Phase Shift through a 75m Texas Bugcatcher Coil
If a Texas Bugcatcher Coil could be turned into a
traveling wave device instead of a standing wave device, the inherent phase shift through the coil would become obvious. I used the Helix option in EZNEC to generate a reasonably close model of a 75m Texas Bugcatcher coil and loaded it with a resistance equal to the coil's characteristic impedance which essentially eliminated the reflected current, leaving the forward current intact and visible. All of the data points on the following web page came from EZNEC. All of the files are available for downloading. Please take a look at: http://www.w5dxp.com/current2.htm -- 73, Cecil http://www.w5dxp.com |
Phase Shift through a 75m Texas Bugcatcher Coil
"Cecil Moore" wrote in message ... If a Texas Bugcatcher Coil could be turned into a traveling wave device instead of a standing wave device, the inherent phase shift through the coil would become obvious. I used the Helix option in EZNEC to generate a reasonably close model of a 75m Texas Bugcatcher coil and loaded it with a resistance equal to the coil's characteristic impedance which essentially eliminated the reflected current, leaving the forward current intact and visible. All of the data points on the following web page came from EZNEC. All of the files are available for downloading. Please take a look at: http://www.w5dxp.com/current2.htm -- 73, Cecil http://www.w5dxp.com Soooo, W8JI and his worshippers were right! Current is just about constant through the loading coil (for traveling wave) but they did not know the case, in which this happens in the antenna circuit, while they were sticking with DC circuit analysis. I hope Roy approves your use of EZNEC for this demonstration and perhaps will admit that they were wrong, and indeed the RF current through standing wave antenna circuit, such a quarter wave resonant vertical monopole, the loading coil has the current drop along the coil (standing wave circuit). This exercise, and Walt's, and whole commotion of reflections and interference has open my antenna eyes a bit wider and allow me to understand better wasaaaap in antenna circuits, which should lead to mo' betta' antenna designs. The only problem I have swallowing Gaussian soup, to understand how on earth and 100 years of antenna tinkering could not see the magic of this (another) miraculous way of getting much more and better signals out of antenna with given power. Thanks guys, this is the best antenna NG, allowing good and questionable posts and free discussion, unlike the TowerTalk antenna reflector where any "heresy" against W8JI crapola "teachings" gets suspended. Yuri, K3BU.us |
Phase Shift through a 75m Texas Bugcatcher Coil
Yuri Blanarovich wrote:
Soooo, W8JI and his worshippers were right! Current is just about constant through the loading coil (for traveling wave) ... Especially since I modeled the coil with lossless wire. :-) *Traveling wave current* amplitude is just about constant at both ends of a loading coil but there's a phase shift as can be seen at: http://www.w5dxp.com/current2.htm In the middle of the coil, the current increases because of the adjacent coil coupling. There is a little drop off (unit percents)in amplitude end-to-end because of I^2*R losses and radiation. But one can consider the coil to be lossless and non-radiating and still get within a few percent of reality. The problem is that W8JI used *standing wave current* for his measurements. What is flowing through the coil is the forward current and reflected current, not the standing wave current. The standing wave current is just standing there as indicated by the cos(kz) term. The amplitude of the standing wave current at any point in the coil or on the antenna has more to do with the phase difference between the forward and reflected currents than anything else. At the tip of the antenna, the forward current and reflected current are equal in magnitude, 180 degrees out of phase, and thus sum to zero. I hope Roy approves your use of EZNEC for this demonstration and perhaps will admit that they were wrong, and indeed the RF current through standing wave antenna circuit, such a quarter wave resonant vertical monopole, the loading coil has the current drop along the coil (standing wave circuit). The current "drop" is an illusion. The current decreases primarily because of out-of-phase addition of the forward and reflected current. If one makes the antenna longer and places the loading coil somewhere else, one can measure a current "rise" through the coil which is still an illusion created by the in-phase addition of the forward and reflected currents. I verified these findings on the bench a couple of months ago using my 75m Texas Bugcatcher coil loaded with a 3K ohm resistor. But I wanted to see if EZNEC agrees. It does. -- 73, Cecil http://www.w5dxp.com |
Phase Shift through a 75m Texas Bugcatcher Coil
On May 6, 9:05 am, Cecil Moore wrote:
In the middle of the coil, the current increases because of the adjacent coil coupling. I'd like to see your Norton analysis of that one. 73, ac6xg |
Phase Shift through a 75m Texas Bugcatcher Coil
Jim Kelley wrote:
I'd like to see your Norton analysis of that one. RF is not DC. Edison questioned how one could measure 100 volts between any two of three terminals. :-) -- 73, Cecil http://www.w5dxp.com |
Phase Shift through a 75m Texas Bugcatcher Coil
Jim Kelley wrote:
I'd like to see your Norton analysis of that one. Take a look at: http://www.k6mhe.com/n7ws/Loaded%20antennas.htm "Figure 2 and Figure 3 clearly show the peaking of the current that Hansen and Cebik write about." -- 73, Cecil http://www.w5dxp.com |
Phase Shift through a 75m Texas Bugcatcher Coil
On 7 May, 06:54, Cecil Moore wrote:
Jim Kelley wrote: I'd like to see your Norton analysis of that one. Take a look at:http://www.k6mhe.com/n7ws/Loaded%20antennas.htm "Figure 2 and Figure 3 clearly show the peaking of the current that Hansen and Cebik write about." -- 73, Cecil http://www.w5dxp.com Thanks for pointing that out Cecil. He did a really good job of explaining things Art |
Phase Shift through a 75m Texas Bugcatcher Coil
Cecil Moore wrote: Jim Kelley wrote: I'd like to see your Norton analysis of that one. RF is not DC. Edison questioned how one could measure 100 volts between any two of three terminals. :-) Are you implying yours is a 3-phase antenna? :-) ac6xg |
Phase Shift through a 75m Texas Bugcatcher Coil
Jim Kelley wrote:
Are you implying yours is a 3-phase antenna? :-) No, just that phasing of RF signals is what is confusing the DC gurus, just like AC phasing confused Edison. -- 73, Cecil http://www.w5dxp.com |
Phase Shift through a 75m Texas Bugcatcher Coil
Cecil Moore wrote:
Jim Kelley wrote: Are you implying yours is a 3-phase antenna? :-) No, just that phasing of RF signals is what is confusing the DC gurus, just like AC phasing confused Edison. What is a DC guru, and why do you address comments to them? As a suggestion, you might consider increasing the current for the EZNEC simulation on your webpage. At 20 amps per division it's plus or minus a pixel at 1024x768. 73, ac6xg |
Phase Shift through a 75m Texas Bugcatcher Coil
Jim Kelley wrote:
As a suggestion, you might consider increasing the current for the EZNEC simulation on your webpage. At 20 amps per division it's plus or minus a pixel at 1024x768. Excellent suggestion, Jim. I'm sure there is a way to do that within the EXCEL charting function but, so far, I haven't figured out how to split the scales. I was going to mow the yard but it's 92 degrees out there and I would rather play with EZNEC anyway. -- 73, Cecil http://www.w5dxp.com |
Phase Shift through a 75m Texas Bugcatcher Coil
Jim Kelley wrote:
As a suggestion, you might consider increasing the current for the EZNEC simulation on your webpage. Done as you suggested by changing the current amplitude scale. What do you think about the simulation? Stand by for more additions to that web page. -- 73, Cecil http://www.w5dxp.com |
Phase Shift through a 75m Texas Bugcatcher Coil
Cecil Moore wrote:
Jim Kelley wrote: As a suggestion, you might consider increasing the current for the EZNEC simulation on your webpage. Done as you suggested by changing the current amplitude scale. What do you think about the simulation? Stand by for more additions to that web page. From what I gathered, the objective of loading the coil with its characteristic impedance was that there would be no reflection. I was therefore surprised when you reported something other than a straight line for the current amplitude along the radiator (let alone an increase at some point). It is now apparent that what you are actually plotting is the superposed forward and reflected currents, and that you have somewhat more than a negligible amount of reflected current. The primary utility in looking at the standing wave profile lies in the fact that it gives an idea of what the superposed field intensity plot might look like in the near field of the antenna. But it is obviously the currents associated with waves traveling on the antenna, both forward and reflected, that actually do the radiating. I agree with you that it is useful to understand the exact effect the loading coil has on the traveling wave, and hence the standing wave profile of the antenna. But I still think it would be prudent to explore and understand the precise nature of the delay through the coil more thoroughly before making too many assumptions about this. 73, Jim AC6XG |
Phase Shift through a 75m Texas Bugcatcher Coil
Jim Kelley wrote:
I was therefore surprised when you reported something other than a straight line for the current amplitude along the radiator (let alone an increase at some point). Just proves that you are not omniscient. Such is the nature of a real world inductance especially close to self-resonance. This is just evidence of another failure of lumped inductance models. The current through a real-world inductance is NOT linear if the operating frequency is within 15% of the self- resonant frequency. For the Nth time, please read and understand the IEEE white paper at: http://www.ttr.com/TELSIKS2001-MASTER-1.pdf -- 73, Cecil http://www.w5dxp.com |
Phase Shift through a 75m Texas Bugcatcher Coil
Cecil Moore wrote: Jim Kelley wrote: I was therefore surprised when you reported something other than a straight line for the current amplitude along the radiator (let alone an increase at some point). Just proves that you are not omniscient. I doubt that proof of that is actually required. In fact, I think you'll find that to be true in general for other people as well. For the Nth time, please read and understand the IEEE white paper at: http://www.ttr.com/TELSIKS2001-MASTER-1.pdf University of Yugoslavia. Yeah, sure thing. Whether it's valid or not, I'm not convinced that's what you have in your EZNEC printout. And unless Roy accounts for "current pileup", it's unlikely that it would show up there. 73, AC6XG |
Phase Shift through a 75m Texas Bugcatcher Coil
"Jim Kelley" wrote in message ... University of Yugoslavia. Yeah, sure thing. ..... What's that supposed to mean? If it is not overpriced American Liberal Alma Mater then is "Yeah"???? Nikola Tesla did more for the mankind than anyone produced by US colleges. Quite an insult to thousands of Slavic engineers immigrants who built IBMs, GMs, etc. Can we discuss technical matters or rather play know-it-alls gurus? Can you point out what is wrong with that paper? 73 Yuri, oK3BU |
Phase Shift through a 75m Texas Bugcatcher Coil
Cecil, W5DXP wrote:
"No, just that phasing of RF signals is what is confusing the DC gurus, just like AC phasing confused Edison." In W8JI`s pages I found this on the subject of "Mobile antennas, short verticals, loading" : It`s long and Tom warns about taking anything from context, so it should be searched out and read in its entirety. I have no quarrel with most of Tom`s pages but find this statement curious: "When current flows in the transmitter-end of the coil, a magnetic field is created. The time-varying magnetic field causes charges in the other turns to instantly move." Instant movement of charges is instant current, and everyone knows that current in a coil lags the voltage. Best regards, Richard Harrison, KB5WZI |
Phase Shift through a 75m Texas Bugcatcher Coil
Richard Harrison wrote:
"When current flows in the transmitter-end of the coil, a magnetic field is created. The time-varying magnetic field causes charges in the other turns to instantly move." Instant movement of charges is instant current, and everyone knows that current in a coil lags the voltage. Instant movement of charges is impossible except in the mind of someone using the lumped-element model. Apparently, anything is possible in that kind of mind. As Dr. Corum said: "Lumped circuit theory fails because it's a *theory* whose presuppositions are inadequate. Every EE in the world was warned of this in their first sophomore circuits course. ... Lumped circuit theory isn't absolute truth, it's only an analytical *theory* - and in those resonators we have the case where this sophomore *theory* fails *experimentally. The engineer must either use Maxwell's equations or distributed elements to model reality." -- 73, Cecil http://www.w5dxp.com |
Phase Shift through a 75m Texas Bugcatcher Coil
Richard Harrison wrote:
Cecil, W5DXP wrote: "No, just that phasing of RF signals is what is confusing the DC gurus, just like AC phasing confused Edison." In W8JI`s pages I found this on the subject of "Mobile antennas, short verticals, loading" : It`s long and Tom warns about taking anything from context, so it should be searched out and read in its entirety. I have no quarrel with most of Tom`s pages but find this statement curious: "When current flows in the transmitter-end of the coil, a magnetic field is created. The time-varying magnetic field causes charges in the other turns to instantly move." Instant movement of charges is instant current, and everyone knows that current in a coil lags the voltage. Best regards, Richard Harrison, KB5WZI Richard, This is one of those situations where the exact definitions are critical. In the case of "current lags voltage" the current is measured through the coil and the voltage is measured between the ends of the coil. The voltage at the input of the coil (to some reference point) is not important; only the voltage across the coil matters. Since there is nothing in the problem statement about the coil output voltage it is not possible to determine if there is any violation of "current lags voltage" or not. I am not saying anything about the assertion from W8JI. The "current lags voltage" principle simply does not settle anything in this case. 73, Gene W4SZ |
Phase Shift through a 75m Texas Bugcatcher Coil
On May 7, 7:26 pm, "Yuri Blanarovich" wrote:
"Jim Kelley" wrote in message If it is not overpriced American Liberal Alma Mater then is "Yeah"???? You make a good point. Nikola Tesla did more for the mankind than anyone produced by US colleges. Let's not get carried away. And I don't think Tesla was from Yugoslavia. Quite an insult to thousands of Slavic engineers immigrants who built IBMs, GMs, etc. No insult to them was ever intended. They didn't write the paper by any chance....?? Can we discuss technical matters or rather play know-it-alls gurus? Can you point out what is wrong with that paper? I wish I understood this obsession you and Cecil have with gurus. I don't share it. About the paper; do you believe everything you read in the papers? As I said, whether it is correct or not, I don't think it is illustrated in Cecil's EZNEC printout. 73, Jim AC6XG |
Phase Shift through a 75m Texas Bugcatcher Coil
"Jim Kelley" wrote in message ups.com... On May 7, 7:26 pm, "Yuri Blanarovich" wrote: "Jim Kelley" wrote in message If it is not overpriced American Liberal Alma Mater then is "Yeah"???? You make a good point. Nikola Tesla did more for the mankind than anyone produced by US colleges. Let's not get carried away. And I don't think Tesla was from Yugoslavia. He was born in Smiljan Lika, Serbia, Yugoslavia, studied at Carl University in Prague. People know more about tinkerer Edison, than about greatest engineering genius who gave us AC and so much. Quite an insult to thousands of Slavic engineers immigrants who built IBMs, GMs, etc. No insult to them was ever intended. They didn't write the paper by any chance....?? Seemed to me implied: "Yeah" = mickey-mouse universities in Yugoslavia (or Eastern Eu). For your information and based on my experience, Eu Universities have much more rigorous programs and theoretical depth than NA-U. When I was working for Big Blue, about half of the bright engineers were graduates from Eastern Europe (post war imigration). Can we discuss technical matters or rather play know-it-alls gurus? Can you point out what is wrong with that paper? I wish I understood this obsession you and Cecil have with gurus. I don't share it. It is more like reaction to people who are sometimes wrong and chime in on a subject with: "hey stupid, it can't be" - parading as omnipotent gurus, instead of asking questions and discussing the matter inteligently and either defending their position or admitting that maybe we were not so stupid and they COULD be wrong, and learn and get better. What we perceive as "gurus" here, is a type of person who is wrong about the subject, tends to get riding on a high horse putting down the opposition, sometimes ridiculing and close minded to any, even elaborate explanation or reasoning. Typically "guru" wants to have their last "right" word, even if realizing that maybe they were wrong, never admitting or giving credit where is due. Looks like too much Woodstock generation getting into engineering and forcing their "truth" to be the only one standing (Global Warming). If often enough repeated in politics, it catches on with halfbright worshippers, but has no place in science. Reality trumps theory, regardless who is trumpeting it. I am sorry that sometimes I get provoked and fire back in a like manner, but when someone is trying to convince me that RF is behaving like DC current, when I got burned my fingers on the bottom of the loading coil, then I just react in kind. About the paper; do you believe everything you read in the papers? As I said, whether it is correct or not, I don't think it is illustrated in Cecil's EZNEC printout. If it is New York Times, definitely not. Technical papers? I would read them carefully, take them with grain of salt, and if important to me, try to understand it and I would verify it if possible. Even if sometimes discussions get tangled here, because some just can't, or don't want to get it, I am gratefull to those involved, because they bring some points, that I would have not paid attention to and missed important link in the chain of knowledge on the subject. Another outcome is, that some subjects in current literature are not all that properly described and warrant more detailed explanation and proof to get corrected, and some discussions here shed some light at it and highlinght need for more down to earth tutorial to set the record straight. 73, Jim AC6XG 73 Yuri, oK3BU |
Phase Shift through a 75m Texas Bugcatcher Coil
Yuri Blanarovich wrote:
What we perceive as "gurus" here, is a type of person who is wrong about the subject, tends to get riding on a high horse putting down the opposition, sometimes ridiculing and close minded to any, even elaborate explanation or reasoning. What really gets my dander up are the gurus who use their respected guru status to mount ad hominem attacks against someone who they know is technically correct. In my book, that is unethical behavior. -- 73, Cecil http://www.w5dxp.com |
Phase Shift through a 75m Texas Bugcatcher Coil
Jim Kelley wrote:
"Let`s not get carried away. And I don`t think Tesla was from Yugoslavia." WebTV is owned by Microsoft and uses their search engine. Searching for "radio amateur fact of the day from Tigertek" immediately turned up their site. I scrolled down to find Tesla`s boat on their March 3 offering: "On May 18, 1899, Nikola Tesla demonstrated a six-foot-long radio-controlled boat to members of the Chicago Commercial Club. He had designed and built the boat the previous year, but only few had seen it prior to the Chicago Commercial Club demonstration. Club members saw that could remotely start the boat`s motor, switch flashing boat lights on and off, and navigate around a miniature lake that he created for the demonstration. Individuals in the crowd shouted commands that he sent wirelessly by radio, so that the astonished crowd could see that the boat actually was being wirelessly-remotely-controlled. Copyright 2005 Tigertek, Inc. It wasn`t until WW-2 and the U.S. invasion of Salerno when the Germans tried to repel it using remotely controlled bombers, that radio control was used so expertly. I first read about Tesla in "Prodigal Genius", a book supplied by some donor ro relieve the boredom aboard my navy ship in WW-2. I was a fiesel engine nechanic interested in electricity and radio so I read it. Tesla impressed me. He was more famous for his inventions of 3-phase electric power, the induction motor, and harnessing the power of Niagra Falls for electricity than he was for radio control. By all accounts he was born in Yugoslavia, educated in Europe, and came to the U.S. to work for Thomas Edison who was unimpressed with Tesla. So Tesla went to George Westinghouse and made a deal. Incidently. nothing exceeds the speed of light, not even photons which are supposed to be massless at rest by Einstein`s special law of relativity. You must have current before it creates a magnetic field. Current is not instantaneous in any case in a conductor where the electrons set in motion do have have mass. Best regards, Richard Harrison, KB5WZI |
Phase Shift through a 75m Texas Bugcatcher Coil
On May 8, 7:19 am, "Yuri Blanarovich" wrote:
He was born in Smiljan Lika, Serbia, Yugoslavia, studied at Carl University in Prague. People know more about tinkerer Edison, than about greatest engineering genius who gave us AC and so much. You may be just a little biased when it comes to Tesla, but understandably so. I am more of an enthusiast than a fanatic. Seemed to me implied: "Yeah" = mickey-mouse universities in Yugoslavia (or Eastern Eu). It was a regretable choice. Cecil has that effect on me occasionally. I did manage to control myself well enough to avoid calling him a "guru" though. :-) I wish I understood this obsession you and Cecil have with gurus. I don't share it. It is more like reaction to people who are sometimes wrong and chime in on a subject with: "hey stupid, it can't be" - parading as omnipotent gurus, instead of asking questions and discussing the matter inteligently and either defending their position or admitting that maybe we were not so stupid and they COULD be wrong, and learn and get better. If only that were a two-way street. What we perceive as "gurus" here, is a type of person who is wrong about the subject, tends to get riding on a high horse putting down the opposition, sometimes ridiculing and close minded to any, even elaborate explanation or reasoning. Typically "guru" wants to have their last "right" word, even if realizing that maybe they were wrong, never admitting or giving credit where is due. Evidently a matter of perception and partiality. Cecil has more 'last words' on this newsgroup than any other contributer by an order of magnitude, and fits the rest of your description to a tee. Looks like too much Woodstock generation getting into engineering and forcing their "truth" to be the only one standing (Global Warming). If often enough repeated in politics, it catches on with halfbright worshippers, but has no place in science. 'Current pileup' could be just such a phenomenon. I am sorry that sometimes I get provoked and fire back in a like manner, but when someone is trying to convince me that RF is behaving like DC current, when I got burned my fingers on the bottom of the loading coil, then I just react in kind. Do I stand accused of trying to convince you that RF behaves like DC? I'm not sure that's entirely fair. I so admit to discouraging belief that RF behaves like magic. Even if sometimes discussions get tangled here, because some just can't, or don't want to get it, I am gratefull to those involved, because they bring some points, that I would have not paid attention to and missed important link in the chain of knowledge on the subject. Another outcome is, that some subjects in current literature are not all that properly described and warrant more detailed explanation and proof to get corrected, and some discussions here shed some light at it and highlinght need for more down to earth tutorial to set the record straight. That's pretty much how I feel about it. I think it helps to keep an open mind and consider all of the relevant facts. 73, Jim AC6XG |
Phase Shift through a 75m Texas Bugcatcher Coil
Jim Kelley wrote:
Evidently a matter of perception and partiality. Cecil has more 'last words' on this newsgroup than any other contributer by an order of magnitude, and fits the rest of your description to a tee. Gurus are individuals who already know everything there is to know and are therefore incapable of learning anything new. That's not me. That's the arrogant individual who lists all the possibilities that might cause someone to disagree with him and none of those possibilities is that he might be wrong. -- 73, Cecil http://www.w5dxp.com |
Phase Shift through a 75m Texas Bugcatcher Coil
On May 8, 9:26 am, Cecil Moore wrote:
Gurus are individuals who already know everything there is to know and are therefore incapable of learning anything new. That's not me. So, that makes you the guy who says things like that about a person just because he disagrees with him on a newsgroup. ac6xg |
Phase Shift through a 75m Texas Bugcatcher Coil
Richard Harrison wrote:
Incidently. nothing exceeds the speed of light, not even photons which are supposed to be massless at rest by Einstein`s special law of relativity. You must have current before it creates a magnetic field. Current is not instantaneous in any case in a conductor where the electrons set in motion do have have mass. Hi Richard, Perhaps it should be noted that electromagnetic waves and photons travel neither faster nor slower than the speed of light in their medium of travel. 73, Jim AC6XG |
Phase Shift through a 75m Texas Bugcatcher Coil
"Jim Kelley" wrote in message ups.com... On May 8, 9:26 am, Cecil Moore wrote: Gurus are individuals who already know everything there is to know and are therefore incapable of learning anything new. That's not me. So, that makes you the guy who says things like that about a person just because he disagrees with him on a newsgroup. ac6xg It is not matter of disagreeing with person, more like discussing the subject, finding out the reality (truth) and learning, sometimes admitting of being off, or wrong, rather than defending the opposite, just because..... Many times I see that people do not bother trying to understand the problem, researching it , but fire off "naaah, it can't be" and reduce their comments to personal attacks. Again, thanks to Cecil, Walt, Richard H and others for their contribution to discussions, their persistence, it opened my antenna horizons and gave me better understanding of wasaaaap with antennas. It will help me in my further exploits and trying to build better arrays and taking advantage of propagation modes and environment. As a contester, I would encourage "gurus" to proclaim their "wisdom", for it will confuse the competition and allow me to beat them by wider margin :-) But as engineer, I would rather know the reality and what's behind it. Just as an example: W8JI proclaims gospel on his web site that Beverage antennas longer than 700 ft (on 160) are useless and waste of effort. When I operated from W8LRL QTH and used his 3000 ft staggered phased JA Beverage, I worked some 25 JAs, when rest of the East Coast hardly worked one or two. Reality trumps over "guru theory" still insisting on his "gospel". 73 Yuri, K3BU |
Phase Shift through a 75m Texas Bugcatcher Coil
Gene, W4SZ wrote:
"The current lags voltage principle does not settle anything in this case." W8JI claims that current flows into a turn at a coil end/s and is induced without delay into all turns of the coil, overcoming delay that the coil might otherwise impose. If that were true, Terman would have told us so. In fact, Terman tells us the opposite is true in explaning the traveling wave tube begining on page 678 of his 1955 opus: "The signal to be amplified is applied to the end of the helix adjacent to the electron gun. Under appropriate operating conditions an amplified signal then appears at the other end of the helix.-------inapplicable info deleted-----. The applied signal propagates around the turns of the helix and produces an electric field that is directed along the helix axis. Since the velocity with which the signal propagates along the helix wire approximates the velocity of light if the frequency is not too low (caveat is unimportant, see footnote in book), the axial field due to the signal advances with a velocity that is very closely the velocity of light multiplied by the ratio of helix pitch to helix circumference." In other words, the axial advance is much like that of a threaded bolt as the pitch angle is always fractional. Kraus details this in his section on helical antennas. Best regards, Richard Harrison, KB5WZI |
Phase Shift through a 75m Texas Bugcatcher Coil
Yuri Blanarovich wrote:
Many times I see that people do not bother trying to understand the problem, researching it , but fire off "naaah, it can't be" and reduce their comments to personal attacks. Apparently you don't see it as much of it as some of the rest of us do. But as engineer, I would rather know the reality and what's behind it. It's probably fair to say that's what motivates most of us, Yuri. It's the one thing most of us here share in common, other than ham radio. Just as an example: W8JI proclaims gospel on his web site that Beverage antennas longer than 700 ft (on 160) are useless and waste of effort. I am not Tom, and you are not Tom. Neither of us speaks for Tom. Tom doesn't even have a dog in this fight as far as I know. So in the interest of maximizing the signal to noise ratio around here, why don't we each let the other just speak for himself. It's much too gossipy otherwise (and not very 'engineer-like'). 73, Jim AC6XG |
Phase Shift through a 75m Texas Bugcatcher Coil
Uim, AC6XG wrote:
"Perhaps it should be noted that electromagnetic waves and photons travel neither faster nor slower than the speed of light in their medium of travel." Yes. Corpuscles and waves have the same velocity given the same medium. Best regards, Richard Harrison, KB5WZI |
Phase Shift through a 75m Texas Bugcatcher Coil
Richard Harrison wrote:
"Since the velocity with which the signal propagates along the helix wire approximates the velocity of light if the frequency is not too low (caveat is unimportant, see footnote in book), the axial field due to the signal advances with a velocity that is very closely the velocity of light multiplied by the ratio of helix pitch to helix circumference." Well done, sir. Kraus details this in his section on helical antennas. Fig. 7-19 is certainly interesting. Cecil owes you a fruit basket I think. ;-) 73, Jim AC6XG |
Phase Shift through a 75m Texas Bugcatcher Coil
Cecil Moore wrote:
What really gets my dander up are the gurus who use their respected guru status to mount ad hominem attacks against someone who they know is technically correct. In my book, that is unethical behavior. Cecil: Which definition of Guru comes closest to your implied meaning: (BTW, I think your use of "guru" is well justified) # (Literally the word guru means teacher) Second level of its meaning is that the guru is a spiritual leader, a saint, a Enlightener. GU (darkness) RU (light); One who brings light into darkness. A teacher.. However, the meaning of the word Guru in Sikh terminology is at a further higher level, and it stands for the 'prophet'. www.sikhlink.com/sikh/terms.htm # ("he who is heavy, weighty"): a spiritual teacher; cf. acarya www.yogajournal.com/newtoyoga/159.cfm # a religious percept or teacher, often the person from whom one receives initiation or consecration. www.trimondi.de/SDLE/Glossary.htm # Literally teacher refers to one of the ten Sikh prophets, the Sikh scripture (Guru Granth Sahib), or God. www.sikhstudy.com/A7terms.html # In general terms, a computer expert. UNIX experts are typically referred to as gurus in polite company. teladesign.com/ma-thesis/glossary.html # a teacher who has attained mastery in the Supracosmic Sphere. www.mudrashram.com/glossarypage.html # "Remover of darkness;" guide. A teacher. Though it can connote a teacher of any subject, guru usually denotes a spiritual teacher or master. |
Phase Shift through a 75m Texas Bugcatcher Coil
Richard Harrison wrote:
Gene, W4SZ wrote: "The current lags voltage principle does not settle anything in this case." W8JI claims that current flows into a turn at a coil end/s and is induced without delay into all turns of the coil, overcoming delay that the coil might otherwise impose. If that were true, Terman would have told us so. In fact, Terman tells us the opposite is true in explaning the traveling wave tube begining on page 678 of his 1955 opus: "The signal to be amplified is applied to the end of the helix adjacent to the electron gun. Under appropriate operating conditions an amplified signal then appears at the other end of the helix.-------inapplicable info deleted-----. The applied signal propagates around the turns of the helix and produces an electric field that is directed along the helix axis. Since the velocity with which the signal propagates along the helix wire approximates the velocity of light if the frequency is not too low (caveat is unimportant, see footnote in book), the axial field due to the signal advances with a velocity that is very closely the velocity of light multiplied by the ratio of helix pitch to helix circumference." In other words, the axial advance is much like that of a threaded bolt as the pitch angle is always fractional. Kraus details this in his section on helical antennas. Best regards, Richard Harrison, KB5WZI Richard, I would never argue with Terman. You completely changed the subject, so I have nothing further to say. The line you quoted above is still correct. Feel free to continue on in whatever new direction you want. 73, Gene W4SZ |
Phase Shift through a 75m Texas Bugcatcher Coil
Jim Kelley wrote:
Perhaps it should be noted that electromagnetic waves and photons travel neither faster nor slower than the speed of light in their medium of travel. Obviously true for traveling waves. But how about the "electromagnetic waves and photons" involved in standing waves? Some folk here would have us believe that they are not moving at all. -- 73, Cecil http://www.w5dxp.com |
Phase Shift through a 75m Texas Bugcatcher Coil
Jim Kelley wrote:
Tom doesn't even have a dog in this fight as far as I know. Tom's web page is in this dog fight. Tom has posted hundreds of postings in the past in support of his instantaneous current with no phase shift through a loading coil. He even "measured" the phase shift through a large coil at 5 nS. Of course, his "measurement" was made with standing- wave current which doesn't change phase. -- 73, Cecil http://www.w5dxp.com |
Phase Shift through a 75m Texas Bugcatcher Coil
Jim Kelley wrote:
Richard Harrison wrote: "Since the velocity with which the signal propagates along the helix wire approximates the velocity of light if the frequency is not too low (caveat is unimportant, see footnote in book), the axial field due to the signal advances with a velocity that is very closely the velocity of light multiplied by the ratio of helix pitch to helix circumference." Fig. 7-19 is certainly interesting. Cecil owes you a fruit basket I think. ;-) Unfortunately, I must disagree (very slightly) with Kraus. Using Kraus' concepts *verbatim*, the delay through a coil would be the same whether the wire is coiled up or straightened out (if I understand correctly what he is saying). On my web page at w5dxp.com/current2.htm I have a 30 turn coil with a diameter of 6" causing a 38 degree phase shift at 3.8 MHz. If the coil were straightened out, it would be about pi*6"*30 = 565 inches or 47 feet. Since a wavelength is about 259 feet at that frequency, 47 feet would be about 65 degrees. So Kraus' rule-of-thumb is off by about 70%. His VF would be about 0.009 where the actual VF is more like 0.106. 65 degrees of wire doesn't replace 65 degrees of antenna. In this case, 65 degrees of wire replaces 38 degrees of antenna. The "missing degrees" are in the impedance discontinuity between the coil and stinger. There is an interaction between turns that increases the VF of the coil so there is a very tiny grain of truth in what Tom says. The interaction between turns increases the coil VF from Kraus' 0.009 to the actual value of 0.016 but certainly not all the way to 1.0 as W8JI asserts. Kraus may have been off by 70% but W8JI is off by 6000% so it seems that Kraus was still a lot closer to the technical truth that W8JI ever was. -- 73, Cecil http://www.w5dxp.com |
Phase Shift through a 75m Texas Bugcatcher Coil
John Smith I wrote:
Which definition of Guru comes closest to your implied meaning: (BTW, I think your use of "guru" is well justified) Sorta using my own definition for "guru" here, John. It is an individual who refuses to listen to anything that mere mortals have to say and either already knows everything or gets any new information from God Almighty himself. Anything that I cannot tell from a religion is being asserted by a "guru". A perfect example is the assertion by W8JI that current travels the length of a 75m Texas Bugcatcher coil instantaneously. If that were true, Intel could speed up its computer buses by adding a 75m Texas Bugcatcher coil to each data/control line, i.e. it is a ridiculous assertion. -- 73, Cecil http://www.w5dxp.com |
Phase Shift through a 75m Texas Bugcatcher Coil
Cecil Moore wrote: Jim Kelley wrote: Perhaps it should be noted that electromagnetic waves and photons travel neither faster nor slower than the speed of light in their medium of travel. Obviously true for traveling waves. But how about the "electromagnetic waves and photons" involved in standing waves? The only kind of electromagnetic waves I know about are the traveling kind. Sorry I can't be more help. 73, ac6xg |
Phase Shift through a 75m Texas Bugcatcher Coil
Cecil Moore wrote: Jim Kelley wrote: Tom doesn't even have a dog in this fight as far as I know. Tom has posted hundreds of postings in the past in support of his instantaneous current with no phase shift through a loading coil. Tom hasn't posted a single word to this thread that I am aware of. The point is if you don't like what he says, you should take it up with him. Know what I mean? ac6xg |
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