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Jim Kelley wrote:
Since a standing wave is an interference pattern created by traveling waves, having 'only standing waves' would obviously be an impossible circumstance. Nonsense. All it takes is two identical waves traveling in opposite directions along the same path. Such happens at the open-circuit or short-circuit point in a 1/4WL stub. I urge you to please investigate the mathematical issues associated with summing counter-rotating vectors. I have, Jim. It is you who seems confused. If two coherent phasors of equal amplitudes and opposite rotations are phasor-added, the resulting total phase is a constant. 1 at zero deg + 1 at zero deg = 2 at zero deg 1 at 45 deg + 1 at -45 deg = 1.4.4 at zero deg etc. Correct me if I'm wrong, but as far as I know you are the only one suggesting that standing wave current phase - whatever that is - could be delayed, measured, and calculated. Nonsense, Jim, standing wave current phase is what EZNEC reports for a standing-wave antenna. If you are incapable of comprehending, don't feel bad. My dog doesn't understand it either but I still love her. -- 73, Cecil, IEEE, OOTC, http://www.w5dxp.com |
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Jim Kelley wrote:
Since a standing wave is an interference pattern created by traveling waves, having 'only standing waves' would obviously be an impossible circumstance. Time to hit the books, Jim. Standing waves are described in Born and Wolf, section 7.4, pages 297-281, 4th edition. "We see that at each instant in time the *phase is constant* through the first medium." The first medium is where the pure standing waves are. Born and Wolf agree that the phase of the standing wave doesn't change throughout the medium. Therefore, its phase cannot be used to measure delay. The same material is covered in "Optics", by Hecht, section 7.1.4, pages 288-293, 4th edition. "[Standing wave phase] "*doesn't rotate* at all, and the resultant wave it represents doesn't progress through space - its a standing wave." If you are incapable of understanding that material, I'm afraid I cannot help you. -- 73, Cecil, IEEE, OOTC, http://www.w5dxp.com |
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On Apr 16, 9:48*pm, Cecil Moore wrote:
Art Unwin wrote: Both sides should be able to understand what the other is saying! Don't worry about it, Art. My dog doesn't understand it either. -- 73, Cecil, IEEE, OOTC, *http://www.w5dxp.com I don't worry about it Cecil but I am concerned at the number of people who consider themselves engineers. Remember that nobody on this group has a true understanding of Maxwells equations! Nobody has proved Maxwell's laws can be proved by adding a time varing field to the Gaussian law of Statics. In fact, it is denied by ALL on this group, Engineers? That to even try is illegal as well as not being correct! Real qualified engineers? And you want this group to understand phase change and travelling waves without the group coming to a consensus on Maxwell's laws? Especially when they demand a definition of equilibrium? Maxwell;'s laws do not include lumped loads in his equations for maximum radiation efficiency, so why do hams use lumped loads with their antennas? Maxwell;'s laws demand that for maximum efficiency equilibrium must be kept, yet hams continue to place verticals at right angles to the earth's surface. And it goes on and on. And engineers continue to misuse what is known as Maxwell's equations. However, despite that I do have a honest question Does the TOA of a dish antenna (CP) change with height similar to other polarisations? Regards Art |
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Since a standing wave is an interference pattern created by traveling
waves, having 'only standing waves' would obviously be an impossible circumstance. By "only standing waves", I meant pure standing waves and nothing else. We've been through this one before. If the SWR is 1:1, there is only a forward traveling wave. If the SWR is not 1:1, there exists a forward traveling wave and a reverse traveling wave. If the SWR is infinite, the amplitudes of the forward wave and reflected wave are equal and a pure standing wave is the result. "Only standing waves" doesn't mean the underlying traveling waves don't exist. It simply means that the amplitudes of the forward wave and reflected wave are equal and therefore all of the energy components in the traveling waves have combined into the standing waves. For instance, a lossless stub would contain "only" standing waves, i.e. pure standing waves. -- 73, Cecil, IEEE, OOTC, http://www.w5dxp.com |
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Cecil Moore wrote:
Jim Kelley wrote: Why not just measure the delay in the instantaneous arrival of energy? Why make something difficult out of a simple problem? My question precisely. How can you tell one packet of energy from another? It's easier than distinguishing one cyle of a sine wave from another. Please do the measurement if you choose and report back what you find. Just send the coil you would like me to test. I'd be pleased to do it for you and report back. ac6xg |
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Cecil Moore wrote:
Since a standing wave is an interference pattern created by traveling waves, having 'only standing waves' would obviously be an impossible circumstance. By "only standing waves", I meant pure standing waves and nothing else. There is still no circumstance where you can have standing waves and nothing else. It's a ridiculous thing to say. We've been through this one before. If the SWR is 1:1, there is only a forward traveling wave. If the SWR is not 1:1, there exists a forward traveling wave and a reverse traveling wave. If the SWR is infinite, the amplitudes of the forward wave and reflected wave are equal and a pure standing wave is the result. "Only standing waves" doesn't mean the underlying traveling waves don't exist. It simply means that the amplitudes of the forward wave and reflected wave are equal and therefore all of the energy components in the traveling waves have combined into the standing waves. For instance, a lossless stub would contain "only" standing waves, i.e. pure standing waves. 'Pure standing wave' is a more useful term. But there is no circumstance under which there is "only" a standing wave. Borrowing from your favorite pro forma rhetorical question: what part of 'interference pattern' don't you understand? ac6xg |
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Cecil Moore wrote:
Jim Kelley wrote: Since a standing wave is an interference pattern created by traveling waves, having 'only standing waves' would obviously be an impossible circumstance. Time to hit the books, Jim. Standing waves are described in Born and Wolf, section 7.4, pages 297-281, 4th edition. "We see that at each instant in time the *phase is constant* through the first medium." The first medium is where the pure standing waves are. Born and Wolf agree that the phase of the standing wave doesn't change throughout the medium. Therefore, its phase cannot be used to measure delay. The same material is covered in "Optics", by Hecht, section 7.1.4, pages 288-293, 4th edition. "[Standing wave phase] "*doesn't rotate* at all, and the resultant wave it represents doesn't progress through space - its a standing wave." If you are incapable of understanding that material, I'm afraid I cannot help you. I understand it well enough to note that it fails to make your point for you. However it does clearly make a point that has never been in contention. Bravo. (Evidently you've forgotten that I was the person who introduced you to Born and Wolf in the first place.) ac6xg |
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Jim Kelley wrote:
Cecil Moore wrote: How can you tell one packet of energy from another? It's easier than distinguishing one cyle of a sine wave from another. Certainly not true if one knows the device under test is shorter than one wavelength. I have measured a lot of voltage circuit delays. I have never measured an energy delay, whatever that is. Just send the coil you would like me to test. I'd be pleased to do it for you and report back. Pick any old air-core in the 50-100 uH range. 20 turns of #16 wire on a 2L pop bottle should do the trick. -- 73, Cecil, IEEE, OOTC, http://www.w5dxp.com |
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Jim Kelley wrote:
There is still no circumstance where you can have standing waves and nothing else. It's a ridiculous thing to say. It was a colloquial choice of words which I previously defined as meaning exactly the same thing as "pure standing wave". If I say, "There's nothing but bicycles on this road today", would you say that's ridiculous because there is also dirt on the road? (Yes, you would). 'Pure standing wave' is a more useful term. If that will keep your panties from getting bunched up, I am all for it. -- 73, Cecil, IEEE, OOTC, http://www.w5dxp.com |
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Cecil Moore wrote:
Jim Kelley wrote: Since a standing wave is an interference pattern created by traveling waves, having 'only standing waves' would obviously be an impossible circumstance. Nonsense. All it takes is two identical waves traveling in opposite directions along the same path. Such happens at the open-circuit or short-circuit point in a 1/4WL stub. Here we have an excellent illustration of the kink in your understanding of wave phenomena. Because just as interference does not cause waves to reflect, waves do not make other waves do things, or turn into something else. A standing wave interference pattern is a result of the presence of traveling waves. One does not replace the other. I urge you to please investigate the mathematical issues associated with summing counter-rotating vectors. I have, Jim. It is you who seems confused. If two coherent phasors of equal amplitudes and opposite rotations are phasor-added, the resulting total phase is a constant. 1 at zero deg + 1 at zero deg = 2 at zero deg 1 at 45 deg + 1 at -45 deg = 1.4.4 at zero deg etc. I you were producing numbers which made sense and were correct, we wouldn't be having this discussion, Cecil. A wave is at various phases along it's length. The phase varies from 0 to 360 every complete cycle. This includes standing waves. Its phase is not "zero" at every point. It's ridiculous to have to point this out to a self proclaimed "expert" on any and every subject such as yourself. Correct me if I'm wrong, but as far as I know you are the only one suggesting that standing wave current phase - whatever that is - could be delayed, measured, and calculated. Nonsense, Jim, standing wave current phase is what EZNEC reports for a standing-wave antenna. In my experience, incorrect assumptions produce incorrect results. The EZNEC results you refer to are an archetypal example of the effect. ac6xg |
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Jim Kelley wrote:
I understand it well enough to note that it fails to make your point for you. You obviously don't understand why a signal that doesn't change phase cannot be used to measure a delay based on phase shift either through a wire or a coil. 1. Every reference says a pure standing wave does not change phase. 2. The current on a 75m mobile antenna is at least 90% standing wave current. 3. Therefo The phase of the current on a 75m mobile antenna cannot be used to measure the delay through the loading coil or even through the straight wire parts of the antenna. 4. Yet, this is exactly the current that w7el and w8ji used in their measurements which yielded "no detectable phase shift" completely unrelated to delay. Here's a question for you: What is the phase shift in the current in 90 degrees of an ideal lossless 1/4WL stub? Until you can provide a valid direct answer to that direct question, you will never understand. -- 73, Cecil, IEEE, OOTC, http://www.w5dxp.com |
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Cecil Moore wrote:
If that will keep your panties from getting bunched up, I am all for it. I'd really prefer that you refrained from commenting about my underwear - or even thinking about them. :-) ac6xg |
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Cecil Moore wrote:
Jim Kelley wrote: I understand it well enough to note that it fails to make your point for you. You obviously don't understand why a signal that doesn't change phase cannot be used to measure a delay based on phase shift either through a wire or a coil. 1. Every reference says a pure standing wave does not change phase. Certainly not as a function of time. Which means it's not an alternating current, and which is why it not considered an actual wave. 2. The current on a 75m mobile antenna is at least 90% standing wave current. And what's the other 10% supposed to be? Please explain how one would go about getting "standing wave current" to flow through something - anything - like a measuring instrument for example. 3. Therefo The phase of the current on a 75m mobile antenna cannot be used to measure the delay through the loading coil or even through the straight wire parts of the antenna. Have you tried pulsing a current through one? I can't imagine there wouldn't be a delay in getting from one end to the other and back. 4. Yet, this is exactly the current that w7el and w8ji used in their measurements No, it is not. Here's a question for you: What is the phase shift in the current in 90 degrees of an ideal lossless 1/4WL stub? I'm reminded of the troll at the bridge. To what phase shift do you refer? With respect to voltage, from one point to another, out and back - you need to be considerably less imprecise if you expect someone to bother to answer (to) you. ac6xg |
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Jim Kelley wrote:
A standing wave interference pattern is a result of the presence of traveling waves. One does not replace the other. Exactly what I have been saying for years against some stiff opposition - welcome aboard. You missed the point which is: If one parses all the energy to the standing wave, it cannot separately be parsed to the traveling waves. Doing so would violate the conservation of energy principle. I you were producing numbers which made sense and were correct, we wouldn't be having this discussion, Cecil. A wave is at various phases along it's length. The phase varies from 0 to 360 every complete cycle. This includes standing waves. Its phase is not "zero" at every point. You obviously don't understand. Whatever the actual phase angle is, for a pure standing wave, at any instant of time, it is constant all up and down the standing wave. NOBODY HAS EVER SAID IT IS ZERO AT EVERY POINT!!! Such an allegation is a ridiculous blowing of smoke. The EZNEC results you refer to are an archetypal example of the effect. The EZNEC results are what they are and have been confirmed by w7el himself. All I can say is: Please correct your mistaken concepts and then rejoin the discussion. What is it about the following EZNEC results that you don't understand? Do you need help in comprehending that a 2.71 degree phase shift in 90 degrees of antenna is a shortfall of 87.29 degrees? EZNEC+ ver. 4.0 thin-wire 1/4WL vertical 4/17/2009 2:57:42 PM --------------- CURRENT DATA --------------- Frequency = 7.29 MHz Wire No. 1: Segment Conn Magnitude (A.) Phase (Deg.) 1 Ground 1 0.00 2 .97651 -0.42 3 .93005 -0.83 4 .86159 -1.19 5 .77258 -1.50 6 .66485 -1.78 7 .54059 -2.04 8 .40213 -2.28 9 .25161 -2.50 10 Open .08883 -2.71 If w7el "measures" the phase shift between segment 3 and segment 7, he will "measure" 1.21 degrees. The actual delay between segment 3 and segment 7 is about 36 degrees. When will anyone understand that fact of physics? -- 73, Cecil, IEEE, OOTC, http://www.w5dxp.com |
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Jim Kelley wrote:
2. The current on a 75m mobile antenna is at least 90% standing wave current. And what's the other 10% supposed to be? The other 10% is the traveling wave that gets radiated of course (neglecting losses). Please explain how one would go about getting "standing wave current" to flow through something - anything - like a measuring instrument for example. Opps, standing wave current doesn't flow so you must have meant how does one eliminate reflections so that nothing except traveling wave current is present. Do you need that explained to you? Have you tried pulsing a current through one? I can't imagine there wouldn't be a delay in getting from one end to the other and back. Exactly, but some would say that's digital, not RF, or that is not steady-state conditions. 4. Yet, this is exactly the current that w7el and w8ji used in their measurements No, it is not. Sorry, you are wrong about that. w7el described in detail what he had measured and it was "total current" which was about 90% standing wave current. Here's what he said: "The result from the second test was a current difference of 5.4%, again with no measurable phase shift." All using the total antenna current which is about 90% standing wave current. What he didn't realize is that a current difference of 5.4% is a calculated phase shift of ~19 degrees, i.e. ARCCOS(1-.054) = ~19 degrees, to which you have previously alluded. Here's a question for you: What is the phase shift in the current in 90 degrees of an ideal lossless 1/4WL stub? I'm reminded of the troll at the bridge. I'm reminded of people who refuse to answer simple questions. One wonders why? The answer is zero degrees. To what phase shift do you refer? With respect to voltage, from one point to another, out and back - you need to be considerably less imprecise if you expect someone to bother to answer (to) you. The context was specified as current. Here is an EZNEC simulation which should help you. http://www.w5dxp.com/stub_dip.EZ Click on currents. You will see that the current phase varies by ~2 degrees end to end in 90 degrees of stub just as it does in a 1/4WL monopole over ground. -- 73, Cecil, IEEE, OOTC, http://www.w5dxp.com |
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Cecil Moore wrote:
The other 10% is the traveling wave that gets radiated of course (neglecting losses). Absurd. Current does not "get radiated". Please explain how one would go about getting "standing wave current" to flow through something - anything - like a measuring instrument for example. Opps, standing wave current doesn't flow so you must have meant how does one eliminate reflections so that nothing except traveling wave current is present. Do you need that explained to you? You claim that W7EL measured the phase shift of standing wave current. He of course made no such claim. So yes, I need you to explain how it is possible for someone do measure a "current" that does not flow. This should be good. ac6xg |
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Jim Kelley wrote:
Cecil Moore wrote: The other 10% is the traveling wave that gets radiated of course (neglecting losses). Absurd. Current does not "get radiated". It's *energy* in the traveling wave that gets radiated. Less energy indeed lowers the current amplitude. The Method Of Moments used by NEC assumes the radiated fields originate from the current in each segment of the antenna. Current is certainly attenuated by radiation as it is by dissipation in lossy transmission lines. In fact, the same attenuation factor is applied to the current equation as is applied to the voltage equation. The difference in the forward current vs the reflected current on the standing-wave antenna at the antenna feedpoint is due to energy lost to radiation. Radiation from an antenna indeed does lower the current on the antenna. The conservation of energy principle strikes again. You can prove it for yourself by modeling a terminated rhombic using EZNEC. The current amplitude in the traveling wave antenna slowly falls as the energy is radiated. Or put in one amp of 70cm current at one end of 200 feet of RG-58 and see how much current you get out at the other end. You don't really think that lumped circuit model assumptions apply to distributed networks, do you? You claim that W7EL measured the phase shift of standing wave current. He of course made no such claim. So yes, I need you to explain how it is possible for someone do measure a "current" that does not flow. This should be good. My point exactly. w7el "measured" the phase shift in current that doesn't flow. That was his entire problem. One cannot measure phase shift in current that doesn't flow, yet that's exactly what w7el and w8ji reported doing. -- 73, Cecil, IEEE, OOTC, http://www.w5dxp.com |
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Cecil Moore wrote:
Jim Kelley wrote: Cecil Moore wrote: The other 10% is the traveling wave that gets radiated of course (neglecting losses). Absurd. Current does not "get radiated". It's *energy* in the traveling wave that gets radiated. Less energy indeed lowers the current amplitude. Agreed. But when discussing current, one should recognize that, with the exception of "non-flowing current" whatever that is, all currents produce a field. Field cancellation is what prevents the transfer of energy. Any of this sounding familiar to you? The standing wave pattern is useful for illustrating what the field interference pattern might look like. w7el "measured" the phase shift in current that doesn't flow. :-) He's good, but he ain't that good. Besides, his meter is the same as yours in that it only responds to waves that travel and currents that flow. The difference I suspect, is in the desired outcome and the rhetoric. I've said my piece. 73, ac6xg |
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Jim Kelley wrote:
You claim that W7EL measured the phase shift of standing wave current. He of course made no such claim. So yes, I need you to explain how it is possible for someone do measure a "current" that does not flow. This should be good. I measured current (of which the definition is well understood except apparently by Cecil), and took a lot of care to do it right. Cecil doesn't like the result, so he's created an imaginary quantity he calls "standing wave current" as an attempt to invalidate the results and promote his imaginative theories. Since it's wholly his creation, its properties are free to be modified as the immediate argument requires. As I, Jim, other posters, and all good texts have explained, a standing wave describes the amplitude envelope of a voltage or current, as a function of position, which results from interference between traveling waves. There's no such thing as "standing wave current". You'll find no references to this fictitious entity in any electromagnetics text. Roy Lewallen, W7EL |
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"Art Unwin" wrote in message ... On Apr 16, 9:48 pm, Cecil Moore wrote: I don't worry about it Cecil but I am concerned at the number of people who consider themselves engineers. Remember that nobody on this group has a true understanding of Maxwells equations! Nobody has proved Maxwell's laws can be proved by adding a time varing field to the Gaussian law of Statics. In fact, it is denied by ALL on this group, Engineers? yes art, electrical engineers, like me, do understand maxwell's equations. and any of them worth their salt will explain, like i have done many times, that it is unecessary to add an explicit time variable to the equations because they are valid at every instant of time... so you end up with f(t)=f(t) which is redundant and doesn't help with the solution of the fields and waves. you have admitted that you don't know fields and waves and that you are not an ee, yet you continue to try to put down those who show a true understanding of the equations and their underlying assumptions. you further demonstrate this by talking about lumped impedances in reference to maxwell's equations and antennas. maxwell's equations describe fields and waves, not the conductors and elements that generate them. they reference the currents and fields, not the wires, capacitors, and inductors. you can derive the properties of inductors and capacitors from maxwell's equations, but you have to look deep inside them and apply the basic laws that make up maxwell's equation to describe the lumped elements. you have yet to explain where equilibrium is required in maxwell's equations. by definition they rely on non-equilibrium conditions to set up waves. you can't have a wave while you are in equilibrium, something has to be putting energy into the system and something has to be moving, that sounds like non-equilibrium to me. |
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Jim Kelley wrote:
Cecil Moore wrote: w7el "measured" the phase shift in current that doesn't flow. :-) He's good, but he ain't that good. Besides, his meter is the same as yours in that it only responds to waves that travel and currents that flow. The difference I suspect, is in the desired outcome and the rhetoric. Indeed. I measured current, which as everyone with a Novice or higher grade license should know is the rate of flow of charge(*). The charge flows in one direction during each half cycle, and in the other during the other half cycle, resulting in current which is positive for half the cycle and negative for the other. This is known as "alternating current". In fact, my measurement system (ferrite core transformers) will only detect alternating current. (*)We very commonly, although technically incorrectly, refer to "current flow" when we really mean "charge flow". Roy Lewallen, W7EL |
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Roy Lewallen wrote:
I measured current (of which the definition is well understood except apparently by Cecil), and took a lot of care to do it right. Cecil doesn't like the result, so he's created an imaginary quantity he calls "standing wave current" as an attempt to invalidate the results and promote his imaginative theories. Since it's wholly his creation, its properties are free to be modified as the immediate argument requires. Roy is mistaken: Here is what Balanis says in "Antennas": "The sinusoidal *current* distribution of long open-ended linear antennas is a *standing wave* ... The *current* and voltage distributions on open-ended wire antennas are similar to the *standing wave* patterns on open-ended transmission lines." Most good fields and waves textbooks provide the equation for standing wave current although the equation for standing-wave voltage is more popular. I certainly did NOT invent the concept. Why do you think a standing-wave antenna would not contain standing-wave current? Roy, here is a public EZNEC support request for you from a loyal EZNEC customer. There are 10 segments in a 1/4WL monopole over average ground. Here is what EZNEC predicts for the currents in each segment. EZNEC+ ver. 4.0 1/4WL vertical monopole 4/17/2009 6:46:08 PM --------------- CURRENT DATA --------------- Frequency = 7.29 MHz Wire No. 1: Segment Conn Magnitude (A.) Phase (Deg.) 1 Ground 1 0.00 2 .97651 -0.42 3 .93005 -0.83 4 .86159 -1.19 5 .77258 -1.50 6 .66485 -1.78 7 .54059 -2.04 8 .40213 -2.28 9 .25161 -2.50 10 Open .08883 -2.71 There's about 9 degrees per segment so the number of degrees between segment 3 and segment 7 is about 36 degrees. If you put your current probes on segment 3 and segment 7, you will measure a 1.21 degree phase shift in those 36 degrees of antenna (just as you did in 36 degrees of loading coil). How do you explain how to accurately measure the number of degrees in a wire given EZNEC's numbers? Why do you think a coil is any different from a straight wire? As I, Jim, other posters, and all good texts have explained, a standing wave describes the amplitude envelope of a voltage or current, as a function of position, which results from interference between traveling waves. The total current is sometimes parsed into a standing wave plus a traveling wave. In a standing-wave antenna like a 1/2WL dipole, the standing wave current is about 90% of the total current while the traveling wave current is about 10% of the total current. Total wave = forward traveling wave + reflected traveling wave. Total wave = standing wave + traveling radiated wave There's no such thing as "standing wave current". You'll find no references to this fictitious entity in any electromagnetics text. Absolutely false. In "Fields and Waves in Modern Radio". by Ramo and Whinnery, 2nd edition, page 42, it gives the equations for standing wave voltage and standing wave current. The current equation is: I = (e^jwt/Z0)[Vfor*e^-jbz - Vref*e^+jbz] -- 73, Cecil, IEEE, OOTC, http://www.w5dxp.com |
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Roy Lewallen wrote:
I measured current, which as everyone with a Novice or higher grade license should know is the rate of flow of charge(*). The charge flows in one direction during each half cycle, and in the other during the other half cycle, resulting in current which is positive for half the cycle and negative for the other. This is known as "alternating current". In fact, my measurement system (ferrite core transformers) will only detect alternating current. Roy, you once verified that the phase of the total current on a 1/2WL dipole changes by less than 10 degrees over the entire 180 degree length of antenna. How can you use a current that changes phase by only 10 degrees in 180 degrees of antenna to measure the delay along the wire? If you cannot do it along a wire, what makes you think you can do it through a loading coil. For the readers who don't know, Roy absolutely refuses to answer any of my questions like the above. -- 73, Cecil, IEEE, OOTC, http://www.w5dxp.com |
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Roy Lewallen wrote:
I measured current (of which the definition is well understood except apparently by Cecil), and took a lot of care to do it right. Here is a challenge for you, Roy. Set up a short resonant 1/2WL dipole. Install your current pickups 1/3 and 2/3 of the way from the feedpoint. Obviously that will be 30 degrees of antenna. Measure the phase shift between those two points using the same care as you used with the loading coil. I'll bet you $100 that you will not measure a 30 degree phase shift. EZNEC says it will be closer to 3 degrees. What would be your conclusion if you indeed did measure 3 degrees as EZNEC predicts? P.S. Would someone please forward this to Roy since he has Plonked me and refused my emails? -- 73, Cecil, IEEE, OOTC, http://www.w5dxp.com |
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On Apr 17, 7:07*pm, "Dave" wrote:
"Art Unwin" wrote in message ... On Apr 16, 9:48 pm, Cecil Moore wrote: I don't worry about it Cecil but I am concerned at the number of people who consider themselves engineers. Remember that nobody on this group has a true understanding of Maxwells equations! Nobody has proved Maxwell's laws can be proved by adding a time varing field to the Gaussian law of Statics. In fact, it is denied by ALL on this group, Engineers? yes art, electrical engineers, like me, do understand maxwell's equations.. and any of them worth their salt will explain, like i have done many times, that it is unecessary to add an explicit time variable to the equations because they are valid at every instant of time... so you end up with f(t)=f(t) which is redundant and doesn't help with the solution of the fields and waves. *you have admitted that you don't know fields and waves and that you are not an ee, yet you continue to try to put down those who show a true understanding of the equations and their underlying assumptions. Hello David I am comfortable that the addition of a time varying field to the laws of statics is a proof of Maxwell. In fact there are many proofs of Maxwsells equations if you read your field and waves books Chapter 2 if I recall as well as the appendix. Dr Davis also stated so and nobody was able to prove him wrong either. So as I have always said I am comfortable with the proof. you further demonstrate this by talking about lumped impedances in reference to maxwell's equations and antennas. *maxwell's equations describe fields and waves, not the conductors and elements that generate them. *they reference the currents and fields, not the wires, capacitors, and inductors. you can derive the properties of inductors and capacitors from maxwell's equations, but you have to look deep inside them and apply the basic laws that make up maxwell's equation to describe the lumped elements. Well again I disagree with you. Maxwells laws as far as we are concerned deals with radiation and maximum efficiency with the basic of equilibrium. As Newton used the term it was a cosmic law as is all his laws thus equilibrium or balance is based on the cosmic which includes outside Earths sphere, a basic for every action and reaction statement. When you introduce a lumped load into radiation without the equal and opposite you have violated Maxwell and Newtons laws, very simple. This is why Maxwell does not include a metric for lumped loads when calculating maximum efficiency via the boundary method. Now as far as waves are concerned science recognises that radiation presents observations that suggest waves but none of these are proven and I believe that particles dominate which if you go along with statics laws is also another proof. you have yet to explain where equilibrium is required in maxwell's equations. *by definition they rely on non-equilibrium conditions to set up waves. *you can't have a wave while you are in equilibrium, something has to be putting energy into the system and something has to be moving, that sounds like non-equilibrium to me. Not so, review the gyroscope action and the sedgewick vehicle all of which rely on balanced circulating rotation within the cosmos. But disregard all the things above that you cannot digest. Use a computer program on antennas that has the option to change human input so that the laws of Maxwell are fiollowed implicity. You put in a vertical design and request maximum gain using the parameters supplied by Maxwell which requires cosmic balance or equilibrium. Antenna computer programs will always put aside the planar design as it lacks equilibrium and will replace it with a tipped vertical antenna. So David you have now put your feet into another puzzle by your falure to digest science. Science and the patent office accept antenna computer programs output which is opposite to your thinking so now you are surrounded by a morass because you denied the good Doctors knowledge of physics. I accept that that you and others do not have a good understanding of equilibrium which generates faults in all associated science problems so our minds will never meet. If you delve into books on Maxwell you will eventually fall upon the use of Gauss. Since there are so many proofs available authors shun from showing the Gaussian connection because of the different metrics involved not because it is not a viable proof. You have a simple option to prove what is correct, use a antenna program with an optimiser and determine what a vertical antenna looks like when seeking maximum efficiency, believe me the radiator will be tipped. So forget every thing else and show the World why computer programs produce faulty results when using your logic. With the use of my logic I have produced a antenna for top band that is rotatable and directional so something I have done is correct and computer programs based on Maxwell produce the same results. Go figure. Now with respect to a dish antenna with CP. Can the dish supply a lower TOA than a planar design at the same height? Regards Art. Ps Mechanical engineering requires adherence to equilibrium, it is not just a electrical thing.I also know little regarding fields and waves but I am profficient in the application of fields operating at the speed of light and their impact on particles for communication and where impact requires mass. |
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"Art Unwin" wrote in message ... On Apr 17, 7:07 pm, "Dave" wrote: Well again I disagree with you. Maxwells laws as far as we are concerned deals with radiation and maximum efficiency with the basic of equilibrium. Maxwell's equations say nothing of efficiency. Nor do they mention equilibrium. Not so, review the gyroscope action and the sedgewick vehicle all of which rely on balanced circulating rotation within the cosmos. you like your mechanics... best to stick with them, you don't understand fields and waves at all. Science and the patent office accept antenna computer programs output the patent office accepts designs for faster than light antennas also. that doesn't prove that there is any science behind them at all. If you delve into books on Maxwell you will eventually fall upon the use of Gauss. Gauss is basic to the Maxwell equations, as i pointed out by it being used within the first few pages of Jackson. believe me the radiator will be tipped. only as far as your brain has tipped. something I have done is correct and computer programs based on Maxwell produce the same results. right, next you'll be rewriting the bible. Ps Mechanical engineering requires adherence to equilibrium if a mechanical system is in equilibrium how much work does it do? |
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Roy Lewallen wrote:
I measured current (of which the definition is well understood except apparently by Cecil), and took a lot of care to do it right. Roy, I am not questioning the accuracy of your measurements - I'm sure they are extremely accurate. What I am questioning are your concepts and conclusions about those measurements. As illustrated in Kraus' antenna book, the end- to-end current phase changes by about 3 degrees for a 1/2WL dipole or a 1/4WL monopole. My question for you is: How can a current that changes phase by 3 degrees in 90 degrees of antenna possibly be used to determine the delay through the antenna wire? - or through a loading coil? Hint: The current in a standing wave antenna is of the form: I(x,t) = C1*cos(bx)*cos(wt) + C2*cos(wt+bx) where C1 C2 i.e. the phase changes primarily with t but primarily not with x. For any time t, the measured phase up and down the antenna changes very little. -- 73, Cecil, IEEE, OOTC, http://www.w5dxp.com |
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On Apr 18, 10:30*am, "Dave" wrote:
"Art Unwin" wrote in message ... On Apr 17, 7:07 pm, "Dave" wrote: Well again I disagree with you. Maxwells laws as far as we are concerned deals with radiation and maximum efficiency with the basic of equilibrium. Maxwell's equations say nothing of efficiency. *Nor do they mention equilibrium. Not so, review the gyroscope action and the sedgewick vehicle all of which rely on balanced circulating rotation within the cosmos. you like your mechanics... best to stick with them, you don't understand fields and waves at all. Science and the patent office accept antenna computer programs output the patent office accepts designs for faster than light antennas also. *that doesn't prove that there is any science behind them at all. If you delve into books on Maxwell you will eventually fall upon the use of Gauss. Gauss is basic to the Maxwell equations, as i pointed out by it being used within the first few pages of Jackson. I suppose that Gauss has a law that is basic to Maxwells laws but certainly not his law of statics. That particular law is two dimension which does not include time. Another scientist supplied to him a similar law that was also two dimensional and it was that law provided the clue which required clarification such that the two dimensional findings had to be added to to match the metrics of equilibrium as required by Newton. If Newton had not required uniformity of metrics it is quite possible his laws would not have been corrected until the discovery by Foucault which Maxwell had deduced or predicted as being present before Foucault was born. That force was determined as being the weak force by me which is required for the grand unification theory (GUT) which unites all the sciences of nature which includes the electricity matter which you have boxed as being isolated from classical physics as we know it. Frankly David, you have over estimated your value as a engineer by your neglect of physics Regards Art believe me the radiator will be tipped. only as far as your brain has tipped. something I have done is correct and computer programs based on Maxwell produce the same results. right, next you'll be rewriting the bible. Ps Mechanical engineering requires adherence to equilibrium if a mechanical system is in equilibrium how much work does it do? |
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Jim Kelley wrote:
Cecil Moore wrote: It's *energy* in the traveling wave that gets radiated. Less energy indeed lowers the current amplitude. Agreed. Note that we agree on almost everything. w7el "measured" the phase shift in current that doesn't flow. :-) He's good, but he ain't that good. Besides, his meter is the same as yours in that it only responds to waves that travel and currents that flow. ... I've said my piece. Exactly, the more you post, the more obvious agreements we have. The following current is the one that dominates a standing-wave antenna. I(x,t) = Imax*cos(kx)*cos(wt) Such a current cannot be used to calculate delay from phase shift in a wire or in a coil. Yet, that is exactly what w7el and w8ji did. Are you leaving the thread because you are on the verge of proving w7el wrong? -- 73, Cecil, IEEE, OOTC, http://www.w5dxp.com |
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"Art Unwin" wrote in message ... On Apr 18, 10:30 am, "Dave" wrote: I suppose that Gauss has a law that is basic to Maxwells laws but certainly not his law of statics. That particular law is two dimension which does not include time. THE Gauss's law is one of the 4 basic maxwell's equations, and it definately is 3d. |
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On Apr 18, 5:32*pm, "Dave" wrote:
"Art Unwin" wrote in message ... On Apr 18, 10:30 am, "Dave" wrote: I suppose that Gauss has a law that is basic to Maxwells laws but certainly not his law of statics. That particular law is two dimension which does not include time. THE Gauss's law is one of the 4 basic maxwell's equations, and it definately is 3d. Great, So now you know that Maxwell did not use the law of statics and thus was unaware of the implied connection of the presence of particles instead of waves.Perhaps now we can leave the subject to rest Art |
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Art Unwin wrote:
On Apr 18, 5:32 pm, "Dave" wrote: "Art Unwin" wrote in message ... On Apr 18, 10:30 am, "Dave" wrote: I suppose that Gauss has a law that is basic to Maxwells laws but certainly not his law of statics. That particular law is two dimension which does not include time. THE Gauss's law is one of the 4 basic maxwell's equations, and it definately is 3d. Great, So now you know that Maxwell did not use the law of statics and thus was unaware of the implied connection of the presence of particles instead of waves.Perhaps now we can leave the subject to rest Art Well Dave, I guess he told you! This has been hilarious, and you have showed exceptional control. tom K0TAR |
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"Tom Ring" wrote in message . net... Well Dave, I guess he told you! This has been hilarious, and you have showed exceptional control. i do it just for the humor value, but he is so predictable by now that its starting to get boring. i think he has run out of laws to break and formulas to rewrite... once he moved on to the cosmic stuff you could tell he had run out of new material. thats probably why he went to the more confined space of the qrz or qth, or whatever that other restricted chat site was, so he could get a less contentious audience. |
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On Apr 10, 2:14*pm, Art Unwin wrote:
The coax ground and the reflector is grounded at the same place at the top of the tower. All horizontal coax is buried. ___________ An r-f ground does not exist at the top of your tower, or any tower. Unless some means is provided to prevent r-f current flow on the outside of the coax and on the tower structure, they will radiate/receive r-f energy. This probably accounts for most of the pattern effects that you didn't expect to have (regardless of the real pattern that your cone and helix generates). RF |
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Richard Fry wrote:
Unless some means is provided to prevent r-f current flow on the outside of the coax and on the tower structure, they will radiate/receive r-f energy. Thus making the vertical antenna longer than 5/8WL. Using the top of the tower for a ground simply makes the tower part of the antenna system turning the entire array into an off-center-fed vertical dipole with the bottom end grounded. For instance, a 1/4WL 20m monopole mounted on top of a 60 foot tower using the tower as the coax shield ground has a take-off-angle of 57 degrees. The highest RF current is near the middle of the tower. :-( To make matters even worse: I had a similar problem with drooping 1/4WL radials DC insulated from the tower. The drooping radials coupled RF into the tower and turned it into a radiator which screwed, oops, I mean skewed the radiation pattern upwards. It took me a long time to figure out why my horizontal dipole was magnitudes better than my 1/4WL vertical on top of the 1.25WL tall tower which was grounded at the bottom and floating at the top. -- 73, Cecil, IEEE, OOTC, http://www.w5dxp.com |
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Roy Lewallen wrote:
I measured current, which as everyone with a Novice or higher grade license should know is the rate of flow of charge(*). The charge flows in one direction during each half cycle, and in the other during the other half cycle, resulting in current which is positive for half the cycle and negative for the other. This is known as "alternating current". In fact, my measurement system (ferrite core transformers) will only detect alternating current. Looking at only one current sample point, one cannot tell the difference between standing waves and traveling waves. However, there is a large difference between standing waves and traveling waves. If you measure the same current phase at two sample points that are physically 30 degrees apart, you are dealing with standing waves. The equation for a standing wave is of the form: I = Imax*cos(bz)*cos(wt) This current is the primary effect on a standing wave antenna and cannot be used to measure the delay between points in an antenna because this current does not change phase relative to length 'z'. If you measure a 30 degree phase shift in the current between two sample points that are 30 degrees apart, you are dealing with traveling waves. The equation for a traveling wave is of the form: I = Imax*cos(wt-bz) This current is a secondary effect on a standing wave antenna. This is the current that changes phase with physical length 'z' but is swamped out by the standing wave. Roy, you listed three possibilities for people who read your postings. 1. Those who agree with you and are therefore right. 2. Those who disagree with you and later change their minds to being right. 3. Those who forever disagree with you and are therefore forever wrong. Please consider the 4th possibility. 4. Roy Lewallen is not omniscient and could possibly be wrong. Again, would someone please forward this to Roy since he has plonked me? -- 73, Cecil, IEEE, OOTC, http://www.w5dxp.com |
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On Apr 19, 8:09*am, Cecil Moore wrote:
Richard Fry wrote: Unless some means is provided to prevent r-f current flow on the outside of the coax and on the tower structure, they will radiate/receive r-f energy. Thus making the vertical antenna longer than 5/8WL. Using the top of the tower for a ground simply makes the tower part of the antenna system turning the entire array into an off-center-fed vertical dipole with the bottom end grounded. For instance, a 1/4WL 20m monopole mounted on top of a 60 foot tower using the tower as the coax shield ground has a take-off-angle of 57 degrees. The highest RF current is near the middle of the tower. :-( To make matters even worse: I had a similar problem with drooping 1/4WL radials DC insulated from the tower. The drooping radials coupled RF into the tower and turned it into a radiator which screwed, oops, I mean skewed the radiation pattern upwards. It took me a long time to figure out why my horizontal dipole was magnitudes better than my 1/4WL vertical on top of the 1.25WL tall tower which was grounded at the bottom and floating at the top. -- 73, Cecil, IEEE, OOTC, *http://www.w5dxp.com Thank you all for those points raised. I added the ground to the dish because I was getting a lot of static one night, I have not had any since but I need time to compare. The grounding line is a heavy silver coated braid connected to each section and to ground. My coax drops to ground and then goes underground for a 100 feet or so and grounded again when it resurfaces. Regards Art |
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Art Unwin wrote:
Thank you all for those points raised. Moral is: There's no such thing as earth "ground" at 50 feet in the air. There are only ground planes, counterpoises, and other conductors that become part of the antenna system. Even the ground wire on an artificial ground device radiates. -- 73, Cecil, IEEE, OOTC, http://www.w5dxp.com |
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On Apr 19, 9:13*am, Cecil Moore wrote:
Art Unwin wrote: Thank you all for those points raised. Moral is: There's no such thing as earth "ground" at 50 feet in the air. There are only ground planes, counterpoises, and other conductors that become part of the antenna system. Even the ground wire on an artificial ground device radiates. -- 73, Cecil, IEEE, OOTC, *http://www.w5dxp.com What if one put a diode in that ground line? |
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On Apr 19, 8:09*am, Cecil Moore wrote:
To make matters even worse: I had a similar problem with drooping 1/4WL radials DC insulated from the tower. The drooping radials coupled RF into the tower and turned it into a radiator which screwed, oops, I mean skewed the radiation pattern upwards. ________________ Some designs use drooping radials to reduce the vertical angle of the peak radiation launched by the monopole section. But that is a conclusion made for an infinite distance, with consideration of the propagation environment on the intrinsic pattern launched by the monopole, and the height of the monopole + its elevated radials above the earth. The link below leads to paste-up of NEC screens showing the performance of a monopole driven against four 1/4-wave, essentially horizontal radials. The entire system is isolated from earth ground. The driving impedance, the elevation pattern shape, and the peak gain are close to "textbook" values for a 1/4-wave monopole driven against a perfect ground plane. A form of this design is being used with good success in the AM broadcast industry -- where using a conventional, buried-radial ground system is impractical due to rocky terrain. The groundwave performance of these systems shows that their intrinsic gain is maximum in the horizontal plane, and very close to the theoretical value of 5.15 dBi. http://i62.photobucket.com/albums/h8...dRadials_1.jpg RF |
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