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Current across the antenna loading coil - from scratch
John Popelish wrote:
If you want to deny the existence of forward and reflected current, be my guest. I deny it. There is only current at a point, just as there is only water jiggling around under a wave on the ocean. Well, that means denial of the distributed network model. I've been waiting for that to happen. There's no point continuing an argument with someone who denies one of the cornerstones of EM wave theory. The distributed network model is accepted as a superset of the lumped circuit model and works when the lumped circuit model fails. The fact remains that standing wave current phase cannot be used to measure phase delay through a wire or through a coil. There is no phase information in standing wave current phase. -- 73, Cecil http://www.qsl.net/w5dxp |
Current across the antenna loading coil - from scratch
John Popelish wrote:
As far as the center conductor is concerned, the shield is the entire universe. My point exactly! There is no third path to the outside world but the standing waves do exist inside the coax without it. -- 73, Cecil http://www.qsl.net/w5dxp |
Current across the antenna loading coil - from scratch
On Sun, 09 Apr 2006 02:55:44 GMT, Cecil Moore
wrote: Please tell us about the position and velocity of each charge carrier, Richard. -no- |
Current across the antenna loading coil - from scratch
On Sun, 09 Apr 2006 03:31:59 GMT, Cecil Moore
wrote: There's no point continuing an argument The triumph of hope over experience. ..... haven't we been here before? And then to continue on to the triumph of experience over hope? Stay tuned for another episode of "Disparate Old Housewives" |
Current across the antenna loading coil - from scratch
Cecil Moore wrote:
John Popelish wrote: As far as the center conductor is concerned, the shield is the entire universe. My point exactly! There is no third path to the outside world but the standing waves do exist inside the coax without it. But from the concept of a standing wave producing a current distribution along the center conductor, the shield performs the function of ground. One current path is along the center conductor (in one of two directions) and the other current path is through the dielectric to the shield, in proportion to the rate of change of voltage at any point on the center conductor. If you eliminate the shield and have a single wire carrying a standing wave over a distant ground, the capacitance per foot drops (raising the characteristic impedance of the transmission line, and losing energy to EM waves, but the displacement current is still there in proportion to the capacitance per foot and the rate of charge of voltage. There is nothing inherently different. Only the loss and ratio of L/C per foot changes. |
Current across the antenna loading coil - from scratch
Richard Clark wrote:
Cecil Moore wrote: There's no point continuing an argument The triumph of hope over experience. When one rejects the distributed network model, one must also reject Maxwell's equations. That seems like a religious act to me, not a technical choice. -- 73, Cecil http://www.qsl.net/w5dxp |
Current across the antenna loading coil - from scratch
John Popelish wrote:
But from the concept of a standing wave producing a current distribution along the center conductor, the shield performs the function of ground. But that is irrelevant. The relevant fact is that there is NO third path to ground yet the standing waves exist anyway. That seems to indicate that the displacement current path to outside world ground is a secondary consideration compared to the superposing of the forward and reflected waves. If you are prepared to reject the distributed network model, are you also prepared to reject Maxwell's equations? Please note that rejection of the distributed network model leaves you with only a model known to fail under certain conditions. In any case, you haven't explained how the unchanging phase in a standing wave current can be used to measure phase shift through a wire or a coil. EZNEC says it is not a valid approach at: http://www.qsl.net/w5dxp/travstnd.GIF -- 73, Cecil http://www.qsl.net/w5dxp |
Current across the antenna loading coil - from scratch
John Popelish wrote:
Cecil Moore wrote: If you want to deny the existence of forward and reflected current, be my guest. I deny it. There is only current at a point, just as there is only water jiggling around under a wave on the ocean. There is only water juggling under two or more waves in the ocean. Anyone who has stood on the beach has observed ocean waves moving in opposite directions. Your assertion is easy to disprove. In the following example, the two sources have identical outputs and are phase locked. They are each equipped with circulators and 50 ohm loads. Source1---------------50 ohm coax------------------Source2 There is current flowing from Source1 heating up Source2's load resistor to the tune of I1^2*R. There is current flowing from Source2 heating up Source1's load resistor to the tune of I2^2*R. Your denial seems to be a denial of reality and more of a religious gut feeling than anything else. If you disconnect Source2 completely in the example above the conditions will be the same except Source1 will be dissipating its own power after a round trip to the open end and back by the energy waves. Incidentally, in the double source example above, which direction is the standing wave current flowing? How could its unchanging phase be used to measure the electrical length of the coax? -- 73, Cecil http://www.qsl.net/w5dxp |
Current across the antenna loading coil - from scratch
Cecil Moore wrote:
John Popelish wrote: If you want to deny the existence of forward and reflected current, be my guest. I deny it. There is only current at a point, just as there is only water jiggling around under a wave on the ocean. Well, that means denial of the distributed network model. Please don't be silly. Distributed networks have points. An infinite number of them. Calculus is used to smoothly move through this infinity of points. But at any particular point, current is defined as the rate of movement of charge past that point. I've been waiting for that to happen. There's no point continuing an argument with someone who denies one of the cornerstones of EM wave theory. So you deny that there are any points (where voltage can be defined or that charge passes) in all distributed networks? How strange. The distributed network model is accepted as a superset of the lumped circuit model and works when the lumped circuit model fails. Yes. And distributed networks are made of a continuum of points. The fact remains that standing wave current phase cannot be used to measure phase delay through a wire or through a coil. There is no phase information in standing wave current phase. Yes. That fact remains. It is a non sequitur in the above discussion, however. That the standing wave current cycle has the same phase along a half wavelength of conductor has nothing to do with the current through that conductor having a point definition (the x in the standing wave function you keep displaying). And at any point the current is AC, spending half of the time going one way, and half of the time going the other way (the positive and negative parts of the cycle in time, defined by cos(kx)*cos(wt), once you pick and x. |
Current across the antenna loading coil - from scratch
Cecil Moore wrote:
John Popelish wrote: But from the concept of a standing wave producing a current distribution along the center conductor, the shield performs the function of ground. But that is irrelevant. The relevant fact is that there is NO third path to ground yet the standing waves exist anyway. That seems to indicate that the displacement current path to outside world ground is a secondary consideration compared to the superposing of the forward and reflected waves. To the center conductor, carrying the standing wave, the shield is the outside world. If there is no shield, the outside world is the outside world, as far as displacement current goes. Do you imagine this current changes in some way other than magnitude and wave velocity when you wrap a shield around a wire carrying a standing wave? If you are prepared to reject the distributed network model, are you also prepared to reject Maxwell's equations? I am prepared to do no such thing. I am explaining distributed network theory to you. Please note that rejection of the distributed network model leaves you with only a model known to fail under certain conditions. Just because I talk about current and voltage at points does not mean I am limited to lumped (idealized) networks. Distributed networks are made of points, too. In any case, you haven't explained how the unchanging phase in a standing wave current can be used to measure phase shift through a wire or a coil. EZNEC says it is not a valid approach at: http://www.qsl.net/w5dxp/travstnd.GIF And I have agreed with that. Why do you keep bringing it up? You are sounding like someone with an obsession. Perhaps you need some down time to let this rattle around in your subconscious. Sometime I'll tell you the dream I had, in which I was a capacitor. Woke up in a cold sweat with an understanding of something fundamental about capacitors I had been stuck on. |
Current across the antenna loading coil - from scratch
Cecil Moore wrote:
John Popelish wrote: Cecil Moore wrote: If you want to deny the existence of forward and reflected current, be my guest. I deny it. There is only current at a point, just as there is only water jiggling around under a wave on the ocean. There is only water juggling under two or more waves in the ocean. Anyone who has stood on the beach has observed ocean waves moving in opposite directions. So waves can move in one or more directions while any bit of water moves only locally. Same with charge. Your assertion is easy to disprove. In the following example, the two sources have identical outputs and are phase locked. They are each equipped with circulators and 50 ohm loads. Source1---------------50 ohm coax------------------Source2 Got it. There is current flowing from Source1 heating up Source2's load resistor to the tune of I1^2*R. There is energy heating the load resistor. The current does not come through the source. It is created at the end of the line by the traveling energy wave. The charge that makes up the current passing back and forth through the load to produce the heat does not come from the source. It comes from the load itself and and the nearby part of the line (within less than a 1/2 wavelength). That charge is caused to move by the energy in the wave. There is current flowing from Source2 heating up Source1's load resistor to the tune of I2^2*R. No, for the same reason. The current is local to the end of the line near the load. It is not current that travels the length of the line from source to load, but the energy in the wave, just as the water from the underwater landslide is not what washes up on the beach a hundred miles away. Local water is pushed up on the beach by the energy in the traveling wave that connects the landslide with the beach. Your denial seems to be a denial of reality and more of a religious gut feeling than anything else. My denial is a recognition that current does not connect the source to the load, traveling energy waves do, however. Local current carries that wave along the line. If you disconnect Source2 completely in the example above the conditions will be the same except Source1 will be dissipating its own power after a round trip to the open end and back by the energy waves. Yes, its wave energy will return to the source and cause current local to the source to pass through that load. Incidentally, in the double source example above, which direction is the standing wave current flowing? At any point that is not a node, back and forth, every cycle. At nodes, back and forth across the dielectric of the line. How could its unchanging phase be used to measure the electrical length of the coax? You measure the difference of the node positions, with and without the coil. The shift in distance (in wavelengths) between the two nodes that straddle the coil is the phase shift of the coil for each of the traveling waves that make up the standing wave. |
Current across the antenna loading coil - from scratch
On Sun, 09 Apr 2006 04:10:15 GMT, Cecil Moore
wrote: That seems like a religious act to me, not a technical choice. seeming again? |
Current across the antenna loading coil - from scratch
John Popelish wrote:
Cecil Moore wrote: John Popelish wrote: At any point along the wire, and at any particular instant, whether as a result of a standing or traveling wave, the current flows in the direction of the wire, one way or the other. Such current does not have a phase. It has a direction. In what direction is the RMS value of standing wave current flowing? That's easy. RMS current is an AC measurement of current along the conductor. Over any integer number of cycles, the total movement of charge is zero. The current spends half the time going one way, and half the time going the other way. This applies to both standing and traveling wave induced currents. The only current that describes a net movement of charge in a single direction is DC. I see that Cecil is still having trouble with RMS, as well as with current. Otherwise he couldn't have come up with the nonsense question In what direction is the RMS value of standing wave current flowing? The RMS value of current doesn't flow. Charge flows, and current is the rate at which it flows. RMS is one way of expressing the magnitude of a time-varying current. In a steady state environment of pure sinusoidal waveforms, any current can be expressed as Ipk * cos(wt + phi) where Ipk is the peak value of the current, w (omega) is the rotational frequency, and phi is the phase angle. This gives you precisely the value of current at any instant in time, t. You can equally well express it as Irms * cos(wt + phi) where Irms is the RMS value of the current. Nothing is lost or gained by choosing one convention or the other, and using RMS doesn't require abandoning the time varying or phase information. (In EZNEC I chose to use RMS; NEC uses peak. They differ only by a constant factor of the square root of 2. Both report phase angle along with amplitude.) In either case, if you know or assume w, the current at any instant is known if you know phi and either Ipk or Irms. A point of clarification to John's posting: When a standing wave exists on a transmission line, the phase of the voltage or current is fixed (other than periodic phase reversals) with position only if the end of the line is open or short circuited. Otherwise, the phase of voltage and current will change with position. Roy Lewallen, W7EL |
Current across the antenna loading coil - from scratch
John Popelish wrote:
Cecil Moore wrote: wrote: But what I really want to know is how Cecil can have current flowing both directions at the same instant of time in a single point of single conductor, Forward and reflected EM waves, of course. Would you like to deny the existence of the two waves in the following equation? I(x,t) = I1*cos(kx+wt) + I2*cos(kx-wt) = Io*cos(kx)*cos(wt) Those two expressions describe patterns of current over time and location that produce current in each direction half the time (except at nodes, where the current is zero). The amplitude of a current cycle is constant for the first one (traveling wave), but the phase differs at different locations (by the amount of kx). The amplitude of current cycle described by the second one (traveling wave) varies with location, and the phase has only two possibilities (one when cos(kx) is positive and 180 degrees different when cos(kx) is negative). But in both cases, current at any point reverses twice a cycle (cos(wt)) and charge goes nowhere over a cycle. I hope you guys realize that the stated equation is correct only when I1 = I2. Otherwise the solution is a sine or cosine function with a phase term. Roy Lewallen, W7EL |
Current across the antenna loading coil - from scratch
John Popelish wrote:
From an earlier posting: For example, if we took a snapshot of the current, all along the line at the moment it peaked it might look like this:(length of arrow represents current magnitude, and head shows direction)(view in fixed width font) ....--- --- -- - - -- --- --- -- - - --...... hole-------------------50 ohm coax-------------------hole x y There is a standing wave current node at 'x' and a standing wave current antinode (loop maximum) at 'y'. Let's say we installed coils at those two points .....--- --- -- - - -- --- --- -- - - --...... hole--------------/////----50 ohm coax----/////------hole x y Now we have current flowing into both ends of the coil located at 'x' and current flowing out of both ends of the coil at 'y'. How does the lumped circuit model handle that situation? Continuing with this posting: Please don't be silly. Distributed networks have points. An infinite number of them. Calculus is used to smoothly move through this infinity of points. But at any particular point, current is defined as the rate of movement of charge past that point. No argument, but that is instantaneous current and that is NOT the subject of this discussion. We are discussing the RMS phasor value of current used by W8JI and W7EL for their measurements and reported by EZNEC as in the graphic at: http://www.qsl.net/w5dxp/travstnd.GIF Please look at the standing wave current phase and tell us how that flat phase curve can be used to measure the phase shift in a wire or coil. The current reported by EZNEC and measured by W8JI and W7EL is *NOT* instantaneous current. It is RMS current. Instantaneous current is completely irrelevant to this discussion. I've been waiting for that to happen. There's no point continuing an argument with someone who denies one of the cornerstones of EM wave theory. So you deny that there are any points (where voltage can be defined or that charge passes) in all distributed networks? How strange. :-) You have your points confused. I was talking about a logical point. Here, let me translate for you. There's no *reason* to continue an argument with someone who denies one of the cornerstones of EM wave theory. John, is English your native language? For the record, I did NOT deny the existence any physical points!!! The fact remains that standing wave current phase cannot be used to measure phase delay through a wire or through a coil. There is no phase information in standing wave current phase. Yes. That fact remains. It is a non sequitur in the above discussion, however. Whoa there, John, it is the entire reason for this discussion. W7EL used that standing wave current phase to try to measure phase shift through a coil. If there is no phase information in standing wave current phase, then his entire argument falls apart and he is back to square one with his flawed lumped circuit model. -- 73, Cecil http://www.qsl.net/w5dxp |
Current across the antenna loading coil - from scratch
John Popelish wrote:
To the center conductor, carrying the standing wave, the shield is the outside world. If there is no shield, the outside world is the outside world, as far as displacement current goes. Do you imagine this current changes in some way other than magnitude and wave velocity when you wrap a shield around a wire carrying a standing wave? No, that is your point, not mine. My point is that displacement current to real ground is non-existent outside of a coax shield (unless common mode current exists) and that it is usually a secondary effect if the coax shield doesn't exist. The primary reason for the variation in standing wave current along the line is the phasor sum of the forward and reflected wave phasors that are rotating in opposite directions. Do you understand phasor addition? 1 at zero + 1 at 180 deg = zero at a standing wave node? Displacement current to real ground doesn't cause that. I am explaining distributed network theory to you. :-) How? By denying the existence of the individual H-fields in forward and reflected EM waves? Now, that's really funny. http://www.qsl.net/w5dxp/travstnd.GIF And I have agreed with that. Why do you keep bringing it up? Because that's the whole point of this discussion. If you agree with that, there is no reason to continue. I just don't care about instantaneous current, Brownian motion, or the exact location and velocity of every electron carrier. There's too much uncertainty involved. -- 73, Cecil http://www.qsl.net/w5dxp |
Current across the antenna loading coil - from scratch
John Popelish wrote:
So waves can move in one or more directions while any bit of water moves only locally. Same with charge. My point exactly. I'm glad you agree. There is energy heating the load resistor. The current does not come through the source. It is created at the end of the line by the traveling energy wave. The H-field energy in the load originated in the source. Current is directly proportional to the H-field in the EM wave. Let me quote Ramo and Whinnery: I = e^jwt/Z0[(V+)(e^-jwz/v) - (V-)(e^jwz/v)] This is the *continuous* equation for source current at z = 0 and load current at z = (distance). Essentially the same equation is found in every reference on transmission lines. They don't say current is "created" at the load. They say current is a *continuous single-valued function* between source and load. Do you have a reference for your "creation" of current? That the H-field experiences a delay and transformation on its way to the load doesn't mean that current is magically created out of thin air at the load. Hang some modulation on the current at the source. You will measure that modulation arriving at the load in the form of current exactly in accordance with the laws of physics embodied in the distributed network model. In a DC circuit, is the current also "created" at the load? My denial is a recognition that current does not connect the source to the load, ... Then by all means, disconnect the source and keep the current. Anything is possible in your mind. Just don't expect that to work in reality. How could its unchanging phase be used to measure the electrical length of the coax? You measure the difference of the node positions, with and without the coil. The shift in distance (in wavelengths) between the two nodes that straddle the coil is the phase shift of the coil for each of the traveling waves that make up the standing wave. Someone needs to tell that to W7EL. I've tried to tell him but instead of thanking me, he 'ploinked' me. -- 73, Cecil http://www.qsl.net/w5dxp |
Current across the antenna loading coil - from scratch
Richard Clark wrote:
Cecil Moore wrote: That seems like a religious act to me, not a technical choice. seeming again? Yes, that way I am the owner of the thought, unlike other people who like to engage in mind fornication using someone else's mind. -- 73, Cecil http://www.qsl.net/w5dxp |
Current across the antenna loading coil - from scratch
Roy Lewallen wrote:
The RMS value of current doesn't flow. I'm glad you agree. That is what I have been telling you for about a year now. Obviously, my question was rhetorical. Your assertion sure shoots down your and W8JI's argument that current flows into the bottom of the coil and out of the top of the coil, doesn't it? You guys reported measuring RMS current flowing into the bottom of the coil and out the top. Now you deny that the current you measured was flowing at all. I would say we are making progress. I have been very careful to talk about the standing wave current *at* the bottom and *at* the top of the coil, not about the current *flowing* into the bottom of the coil and out the top of the coil as you and W8JI have. -- 73, Cecil http://www.qsl.net/w5dxp |
Current across the antenna loading coil - from scratch
Roy Lewallen wrote:
I hope you guys realize that the stated equation is correct only when I1 = I2. Otherwise the solution is a sine or cosine function with a phase term. Of course, I1=I2 is the definition of a standing wave which is the topic of this discussion. Any current left over is traveling wave current, by definition. The concept is akin to the separation of differential current from common-mode current. Differential currents are equal by definition. Standing wave component currents are equal by definition. -- 73, Cecil http://www.qsl.net/w5dxp |
Current across the antenna loading coil - from scratch
Cecil Moore wrote:
I have been very careful to talk about the standing wave current *at* the bottom and *at* the top of the coil, not about the current *flowing* into the bottom of the coil and out the top of the coil as you and W8JI have. Cecil, The wave is stationary. The current is not. It is as simple as that. Distinctions between *at* and *flowing* are meaningless. Current is what it is, and mere words don't change anything. You seem to be reduced to arguments about semantics, which is both good news and bad news. The good news is that there does not appear to be any disagreement about the physics. The bad news is that the argument will never end. 73, Gene W4SZ |
Current across the antenna loading coil - from scratch
Roy Lewallen wrote:
John Popelish wrote: That's easy. RMS current is an AC measurement of current along the conductor. Over any integer number of cycles, the total movement of charge is zero. The current spends half the time going one way, and half the time going the other way. This applies to both standing and traveling wave induced currents. The only current that describes a net movement of charge in a single direction is DC. I see that Cecil is still having trouble with RMS, as well as with current. Otherwise he couldn't have come up with the nonsense question He seems to confuse energy in the wave traveling along a conductor with the current it induces along that conductor, as it travels. I have had a few such mental blocks and made a fool of myself a couple times because I was sure I was right. But when the light finally came on, lots of related things suddenly crystallized in my mind and I jumped to a better understanding. One of my regrets is that I didn't go back and apologize to my 7th grade science teacher for arguing with him with so little tact, when I found out a year later that he had been right and it was I who had been laboring under a misconception. Same thing happened, on a different topic, in 8th grade science. So I think I understand his attitude. I just hope that he sees that my intentions are honorable, in this discussion. I am not attacking him, but working for his understanding. I may be mistaken and end up having another seventh grade moment here, but I'm not trying to embarrass him. In what direction is the RMS value of standing wave current flowing? The RMS value of current doesn't flow. Charge flows, and current is the rate at which it flows. RMS is one way of expressing the magnitude of a time-varying current. In a steady state environment of pure sinusoidal waveforms, any current can be expressed as Ipk * cos(wt + phi) where Ipk is the peak value of the current, w (omega) is the rotational frequency, and phi is the phase angle. This gives you precisely the value of current at any instant in time, t. You can equally well express it as Irms * cos(wt + phi) where Irms is the RMS value of the current. Nothing is lost or gained by choosing one convention or the other, and using RMS doesn't require abandoning the time varying or phase information. (In EZNEC I chose to use RMS; NEC uses peak. They differ only by a constant factor of the square root of 2. Both report phase angle along with amplitude.) In either case, if you know or assume w, the current at any instant is known if you know phi and either Ipk or Irms. A point of clarification to John's posting: When a standing wave exists on a transmission line, the phase of the voltage or current is fixed (other than periodic phase reversals) with position only if the end of the line is open or short circuited. Otherwise, the phase of voltage and current will change with position. Is that because the result is not a pure standing wave (superposition of two equal and oppositely traveling waves), but a superposition of a pair of traveling oppositely traveling waves of different amplitudes? |
Current across the antenna loading coil - from scratch
On Sun, 09 Apr 2006 13:12:29 GMT, Cecil Moore
wrote: Yes, that way I am the owner of the thought, unlike other people who like to engage in mind fornication using someone else's mind. Glad to hear you only use your own mind for that. So your religion practices Onanism? |
Current across the antenna loading coil - from scratch
Cecil Moore wrote:
John Popelish wrote: From an earlier posting: For example, if we took a snapshot of the current, all along the line at the moment it peaked it might look like this:(length of arrow represents current magnitude, and head shows direction)(view in fixed width font) ....--- --- -- - - -- --- --- -- - - --...... hole-------------------50 ohm coax-------------------hole x y There is a standing wave current node at 'x' and a standing wave current antinode (loop maximum) at 'y'. Let's say we installed coils at those two points ....--- --- -- - - -- --- --- -- - - --...... hole--------------/////----50 ohm coax----/////------hole x y Now we have current flowing into both ends of the coil located at 'x' and current flowing out of both ends of the coil at 'y'. How does the lumped circuit model handle that situation? If we assume the coil is an idealized lumped inductance with no stray capacitance at all (not a real inductor) then it would have the same instantaneous current at each end and that current would be zero, since it has zero size. In other words it would fit entirely in the point that holds the node. Real inductors with stray capacitance and imperfect magnetic coupling for all parts of its internal current path, would have a phase shift in the current at opposite ends, so they would have current at their ends that was 180 degrees out of phase, if they were centered on the node points. For half of each cycle, current would be entering each end, and for the other half of each cycle, current would be leaving each end. Both those currents would detour out the sides f the inductor into displacement current through the stray capacitance of the surface of the inductor to its surroundings. I think (with very little actual knowledge of the software) this conceptual model is how EZNEC handles current through a modeled inductor and how it can have different currents at the inductor ends, without being aware of whether those currents are driven by traveling or standing waves. It is all based on current through inductor segments and voltage across capacitive segments. If the segments are small enough, it is a good approximation of a distributed solution. Continuing with this posting: Please don't be silly. Distributed networks have points. An infinite number of them. Calculus is used to smoothly move through this infinity of points. But at any particular point, current is defined as the rate of movement of charge past that point. No argument, but that is instantaneous current and that is NOT the subject of this discussion. We are discussing the RMS phasor value of current used by W8JI and W7EL for their measurements and reported by EZNEC as in the graphic at: I am not arguing this point. RMS values capture the amplitude of a cycle of variation. I am inside the cycle. But the two views are consistent. http://www.qsl.net/w5dxp/travstnd.GIF Please look at the standing wave current phase and tell us how that flat phase curve can be used to measure the phase shift in a wire or coil. The current reported by EZNEC and measured by W8JI and W7EL is *NOT* instantaneous current. It is RMS current. Instantaneous current is completely irrelevant to this discussion. I am not arguing for the validity of that measurement. Argue about it with someone who is. I've been waiting for that to happen. There's no point continuing an argument with someone who denies one of the cornerstones of EM wave theory. So you deny that there are any points (where voltage can be defined or that charge passes) in all distributed networks? How strange. :-) You have your points confused. I was talking about a logical point. Here, let me translate for you. There's no *reason* to continue an argument with someone who denies one of the cornerstones of EM wave theory. John, is English your native language? For the record, I did NOT deny the existence any physical points!!! The fact remains that standing wave current phase cannot be used to measure phase delay through a wire or through a coil. There is no phase information in standing wave current phase. Yes. That fact remains. It is a non sequitur in the above discussion, however. Whoa there, John, it is the entire reason for this discussion. According to you, you are finished talking about coils, and want to delve strictly into wave concepts. To honor your request, I have tried to keep the discussion general, and avoid bringing up the effect on and measurements of coils. But, in this post, you talk about almost nothing else but coils. I get the distinct feeling that you want to win a debate far more than you want to reach an understanding with no internal contradictions. And you are willing to use dishonest debate tactics (like telling me not to discuss a topic with you, and then telling me that that exact topic is "the entire reason for this discussion". Do you get beat up a lot in face-to-face arguments? W7EL used that standing wave current phase to try to measure phase shift through a coil. If there is no phase information in standing wave current phase, then his entire argument falls apart and he is back to square one with his flawed lumped circuit model. Yes. But I cannot concede that point of discussion for someone else. Are you going to hit me over the head with this till every person in the World agrees with you? I am trying to think the general case through with you. In case you don't realize, there is more than one person out here, responding to you. You remind me of a type of insanity where the sufferer thinks that everything he is experiencing an organized illusion by a single offending intelligence (you against the Matrix) bent on forcing him to think that a lie is the truth, regardless of who or what he deals with. Everyone he meets, every apparently random happenstance, the actions of his dog and the weather, generally, are all a conspiracy to force him to think that black is white, and he isn't going to fall for it. If you cannot carry on a conversation with more than one person at a time, and treat each of them as a separate mind, then this is the wrong venue for you. |
Current across the antenna loading coil - from scratch
Cecil Moore wrote:
John Popelish wrote: To the center conductor, carrying the standing wave, the shield is the outside world. If there is no shield, the outside world is the outside world, as far as displacement current goes. Do you imagine this current changes in some way other than magnitude and wave velocity when you wrap a shield around a wire carrying a standing wave? No, that is your point, not mine. My point is that displacement current to real ground is non-existent outside of a coax shield (unless common mode current exists) With you, so far.. and that it is usually a secondary effect if the coax shield doesn't exist. And then we part ways. The primary reason for the variation in standing wave current along the line is the phasor sum of the forward and reflected wave phasors that are rotating in opposite directions. Do you understand phasor addition? 1 at zero + 1 at 180 deg = zero at a standing wave node? Displacement current to real ground doesn't cause that. I am making the point that if the displacement currents were insignificant, outside a coax, then the speed of light for waves out there would be infinite. And they are not, therefore those displacement currents cannot be assumed to be insignificant. I am explaining distributed network theory to you. :-) How? By denying the existence of the individual H-fields in forward and reflected EM waves? Now, that's really funny. Exactly the opposite. I am explaining the distributed effect of the E field along the wave. http://www.qsl.net/w5dxp/travstnd.GIF And I have agreed with that. Why do you keep bringing it up? Because that's the whole point of this discussion. If you agree with that, there is no reason to continue. I just don't care about instantaneous current, Brownian motion, or the exact location and velocity of every electron carrier. There's too much uncertainty involved. You are avoiding the very facts that would allow you to make an air tight argument for your beliefs about "the whole point of the discussion". You somehow picture current as a continuous thing from one end of a conductor to the other, when it carries a traveling energy wave. This is a misconception. You appear to accept that current is a localized kind of thing (parts of the conductor carry current, but those parts are separated by nodes) when two traveling waves going in opposite directions superpose, but have no concept that explains how this happens, only a mathematical function that quantifies it. What you don't get is, that the currents that each of those traveling waves would have generated were localized, to begin with. Local current cycles and voltage cycles are the water the energy waves ride on over arbitrarily long distances along conductors and transmission lines. I know you don't care about this factoid, but understanding it would allow you to think about "the entire reason for this discussion" much more clearly. |
Current across the antenna loading coil - from scratch
Cecil Moore wrote:
John Popelish wrote: So waves can move in one or more directions while any bit of water moves only locally. Same with charge. My point exactly. I'm glad you agree. We shall see. There is energy heating the load resistor. The current does not come through the source. It is created at the end of the line by the traveling energy wave. The H-field energy in the load originated in the source. Yes. Current is directly proportional to the H-field in the EM wave. Yes. Let me quote Ramo and Whinnery: I = e^jwt/Z0[(V+)(e^-jwz/v) - (V-)(e^jwz/v)] This is the *continuous* equation for source current at z = 0 and load current at z = (distance). Essentially the same equation is found in every reference on transmission lines. Yes. That equation describes the instantaneous current you would find at any point as the wave pases through it. It does not imply that the current at one point is the same current at another point. It implies a continuity of the energy wave. At some points along that wave, the current has some positive value (charge going in the same direction as the wave. At other points, the current has some negative value, indicating that charge is moving the opposite way from the wave direction. The current is continuous only in that there is a smooth, sinusoidal variation in its magnitude and direction as you look along the wave path. but the current at one point is not the current at some other point. They don't say current is "created" at the load. They say current is a *continuous single-valued function* between source and load. A current described by a continuous single valued function is not a continuous current. The water that drowns people in a tidal wave in California is a current dragged over the beach by an energy wave that caused a continuous pattern on of local currents from the landslide in Hawaii. But the actual water current (movement of water molecules carrying the wave energy) did not flow continuously from Hawaii to California. There are no Hawaiian fish carried to California by a current of water that connected those two locations. Do you have a reference for your "creation" of current? Only Maxwell's equations. That the H-field experiences a delay and transformation on its way to the load doesn't mean that current is magically created out of thin air at the load. Current is created and reversed (charge is sloshed back and forth) all along the line, from source to load. Just as water is moved up and down all along the path of a wave over the surface of the water. But if you pick any bit of water, it does not follow the wave. Hang some modulation on the current at the source. You will measure that modulation arriving at the load in the form of current exactly in accordance with the laws of physics embodied in the distributed network model. Yes, delayed by the speed of light in that medium. In a DC circuit, is the current also "created" at the load? No. DC has an infinite wavelength, so there is no significant distance (in wavelength units) no matter how far apart the source and load appear to be. If a battery near earth is connected to a load near Alpha Centauri by a perfectly conducting loop, and you consider the DC case (DC has an infinite duration), then there is no significant distance between that source and load, so local current connects them. Electrons that are pushed out of the battery will reach the load and return to the battery. The definition of "local" is wavelength dependent. Back to the RF case: Do you imagine that electrons from the source reach the load? My denial is a recognition that current does not connect the source to the load, ... Then by all means, disconnect the source and keep the current. Be happy to. For the amount of time it takes for a wave to pass the full length of the line, energy will continue to be delivered to the load (current will pass through it), even though the source has been disconnected and causes no further current in the line. Anything is possible in your mind. Just don't expect that to work in reality. I am doing my best to limit my mind to strictly what reality allows, in this discussion. How could its unchanging phase be used to measure the electrical length of the coax? You measure the difference of the node positions, with and without the coil. The shift in distance (in wavelengths) between the two nodes that straddle the coil is the phase shift of the coil for each of the traveling waves that make up the standing wave. Someone needs to tell that to W7EL. I've tried to tell him but instead of thanking me, he 'ploinked' me. Perhaps he has lost interest in this thread. Perhaps he is taking this topic personally. Perhaps he enjoys yanking your chain. Perhaps ... What does any of that have to do with our conversation? Your thoughts are in a rut. |
Current across the antenna loading coil - from scratch
Gene Fuller wrote:
The good news is that there does not appear to be any disagreement about the physics. On the contrary, Gene. The disagreement is whether W7EL's use of standing wave current phase to try to determine phase shift through a coil was valid or not. That is the present point of disagreement. I have posted what you said many times but W7EL doesn't read my postings. So would you kindly point out to W7EL that there is no phase information in standing wave current phase? -- 73, Cecil http://www.qsl.net/w5dxp |
Current across the antenna loading coil - from scratch
John Popelish wrote:
He seems to confuse energy in the wave traveling along a conductor with the current it induces along that conductor, as it travels. It's not confusion, John. It is engineering convention. Every engineering reference book I have refers to current flow at one point or another. Most of them also refer to power flow. "Transmission Lines and Networks", by Walter C. Johnson even refers to "The Conservation of Power Principle". Since there is no such thing as an RF battery, we know exactly what Mr. Johnson meant. You are discussing the conventions used by physicists. Since this is basically an RF engineering convention newsgroup, you need to adjust your concepts accordingly or tell everyone that you are nit-picking based on the conventions from the field of pure physics. In the engineering world: Power companies generate power and transfer the power to the consumers over transmission lines. RF transmitters generate power which is transferred over the transmission line and radiated by the antenna. There is always a convention for placing an arrow on a wire to indicate direction of current flow, whether RMS AC or DC or RMS RF. The AC conventions are left over from the DC conventions. If you are trying to change those conventions, please say so. Food for thought: If an electron can pass through two different holes at the same time, can it also travel in two directions at the same time? Quantum physics says that is a possibility. Is that because the result is not a pure standing wave (superposition of two equal and oppositely traveling waves), but a superposition of a pair of traveling oppositely traveling waves of different amplitudes? Yes, but the definition of a standing wave is that the two waves are of equal amplitudes. The wave you are describing is a hybrid wave containing both a traveling wave and a standing wave. Any real-world system contains hybrid waves in various ratios of traveling waves to standing waves. -- 73, Cecil http://www.qsl.net/w5dxp |
Current across the antenna loading coil - from scratch
Richard Clark wrote:
Glad to hear you only use your own mind for that. So your religion practices Onanism? It means that if I decide to mentally masturbate, I'll use my own mind, thank you, not someone else's mind, as do a lot of the posters on this newsgroup. -- 73, Cecil http://www.qsl.net/w5dxp |
Current across the antenna loading coil - from scratch
On Sun, 09 Apr 2006 17:53:07 GMT, Cecil Moore
wrote: So your religion practices Onanism? It means that if I decide to mentally masturbate, I'll use my own mind, thank you, not someone else's mind, as do a lot of the posters on this newsgroup. Lot of bafflegab in that. I will take it to mean yes. |
Current across the antenna loading coil - from scratch
John Popelish wrote:
If we assume the coil is an idealized lumped inductance with no stray capacitance at all (not a real inductor) then it would have the same instantaneous current at each end and that current would be zero, since it has zero size. In other words it would fit entirely in the point that holds the node. And such a coil is impossible in the real world so why even mention it? I want to hear about real world one foot long, 100 uH coils. Real inductors with stray capacitance and imperfect magnetic coupling for all parts of its internal current path, would have a phase shift in the current at opposite ends, so they would have current at their ends that was 180 degrees out of phase, if they were centered on the node points. Yes, now please tell that to W8JI and W7EL. They are not listening to me. I am not arguing for the validity of that measurement. Argue about it with someone who is. That's my entire argument at the moment and W7EL is avoiding that argument like a plague. In case you don't realize, there is more than one person out here, responding to you. Please forgive me for not recognizing which of the ten individual junk yard dog "experts" is biting my ankles at any particular time. :-) You remind me of a type of insanity where the sufferer thinks that everything he is experiencing an organized illusion by a single offending intelligence (you against the Matrix) bent on forcing him to think that a lie is the truth, regardless of who or what he deals with. Everyone he meets, every apparently random happenstance, the actions of his dog and the weather, generally, are all a conspiracy to force him to think that black is white, and he isn't going to fall for it. IMHO, hardly anyone here on r.r.a.a is interested in technical facts. Most "experts" think they already know everything, wouldn't recognize a differing concept if it bit them in the arse, and are more dedicated to preserving the pecking order than anything else. 'Course, I am only human and could, therefore, unlike the omniscient experts, be wrong about that. -- 73, Cecil http://www.qsl.net/w5dxp |
Current across the antenna loading coil - from scratch
John Popelish wrote:
I am making the point that if the displacement currents were insignificant, outside a coax, then the speed of light for waves out there would be infinite. And they are not, therefore those displacement currents cannot be assumed to be insignificant. But I am not talking about displacement currents within the transmission line, as exists in free space. I am talking *solely* about the displacement currents to *earth ground*. I contend that those are often secondary effects as proven by the coax example. Just how much displacement current to "earth ground" is there for a coil located halfway between here and Alpha Centauri? Exactly the opposite. I am explaining the distributed effect of the E field along the wave. And completely ignoring the H-field? In the treatment of those fields, the only variation is Z0. For EM fields, there is no "across" and no "through". The difference between voltage and current essentially disappears except for their Z0 ratio. The equation for current in a transmission line is identical to the equation for voltage except for the Z0 term. Current "drops" are commonplace in lossy transmission lines. For instance, what is the current at the end of 200 feet of RG-58 terminated by a 50 ohm antenna used on 446 MHz when the source current is 2 amps? You are avoiding the very facts that would allow you to make an air tight argument for your beliefs about "the whole point of the discussion". You somehow picture current as a continuous thing from one end of a conductor to the other, when it carries a traveling energy wave. This is a misconception. Maybe in the field of physics - not in the field of RF engineering. For any two current points, I can calculate a point in between. Sorry, but that's a characteristic of a *continuous* single-valued function and can be proven mathematically. I admit to being a EE/math major. I didn't take many pure physics courses so I am missing your point about me being able to prove anything additional. Maybe it will dawn on me after awhile. What you don't get is, that the currents that each of those traveling waves would have generated were localized, to begin with. I realize that is the physicist talking and it agrees with my earlier assertion that standing wave current doesn't flow. I guess I'm so dense that I need help in proving what you think I can prove with that information. Right now, I am apparently missing something, maybe because of too much California Merlot. -- 73, Cecil http://www.qsl.net/w5dxp |
Current across the antenna loading coil - from scratch
John Popelish wrote:
The definition of "local" is wavelength dependent. Since the reality in which we exist has been proven to be non-local in nature, I'm wondering what is your point? Back to the RF case: Do you imagine that electrons from the source reach the load? Maybe for DC. But depending upon the length of the transmission line, probably not for HF RF. Is that a rhetorical question? Someone needs to tell that to W7EL. I've tried to tell him but instead of thanking me, he 'ploinked' me. Perhaps he has lost interest in this thread. Perhaps he is taking this topic personally. Perhaps he enjoys yanking your chain. Perhaps ... .... he is afraid of losing his "expert" status? What does any of that have to do with our conversation? Everything. That's what this thread is all about. I will repeat: Can the standing wave current phase, with its unchanging phase, be used to measure the phase shift through a wire or coil? That's the admittedly narrow present topic. The answer is either 'yes' or 'no'. After we answer that narrow technical question, the discussion can procede. -- 73, Cecil http://www.qsl.net/w5dxp |
Current across the antenna loading coil - from scratch
Richard Clark wrote:
Lot of bafflegab in that. I will take it to mean yes. Whatever way you choose to "take it" has absolutely no effect on any reality except your own personal reality existing only in your head. Enjoy! -- 73, Cecil http://www.qsl.net/w5dxp |
Current across the antenna loading coil - from scratch
Cecil Moore wrote:
John Popelish wrote: If we assume the coil is an idealized lumped inductance with no stray capacitance at all (not a real inductor) then it would have the same instantaneous current at each end and that current would be zero, since it has zero size. In other words it would fit entirely in the point that holds the node. And such a coil is impossible in the real world so why even mention it? Because it is the limiting case of the possible. Understanding why it is the limit interests me. I want to hear about real world one foot long, 100 uH coils. Then you have changed your mind from a few days ago. No problem for me. Real inductors with stray capacitance and imperfect magnetic coupling for all parts of its internal current path, would have a phase shift in the current at opposite ends, so they would have current at their ends that was 180 degrees out of phase, if they were centered on the node points. Yes, now please tell that to W8JI and W7EL. They are not listening to me. I just did. I hope you realize that anyone is perfectly free to ignore anything posted to this or any other newsgroup, and long as it pleases them. If you are going to have trouble sleeping because you can't get complete agreement from everyone who you have ever seen post to this group, your problems are a lot bigger than coils and waves. I am not arguing for the validity of that measurement. Argue about it with someone who is. That's my entire argument at the moment and W7EL is avoiding that argument like a plague. That is their prerogative. Deal with it. I am putting considerable effort to understand the physics of the situation and to share my thoughts with you. If this is no interest to you, I will discuss this interesting topic with someone else. In case you don't realize, there is more than one person out here, responding to you. Please forgive me for not recognizing which of the ten individual junk yard dog "experts" is biting my ankles at any particular time. :-) I am insulted that you include me in that derogatory characterization. I have been polite, patient and respectful with you in this discussion. You remind me of a type of insanity where the sufferer thinks that everything he is experiencing an organized illusion by a single offending intelligence (you against the Matrix) bent on forcing him to think that a lie is the truth, regardless of who or what he deals with. Everyone he meets, every apparently random happenstance, the actions of his dog and the weather, generally, are all a conspiracy to force him to think that black is white, and he isn't going to fall for it. IMHO, hardly anyone here on r.r.a.a is interested in technical facts. Most "experts" think they already know everything, wouldn't recognize a differing concept if it bit them in the arse, and are more dedicated to preserving the pecking order than anything else. 'Course, I am only human and could, therefore, unlike the omniscient experts, be wrong about that. And that is exactly why I have refrained from personal attacks (though I have indulged in a few observations as above, because I think considering them might open your eyes to how you appear to others, and how that interferes with your arguments. So even those observations were not made in an attempt to win an argument with you, but to assist you in thinking more clearly. For the most part, I have tried to talk about physics, not pecking order or personalities. But you keep cutting me off, saying you are not interested in physics, but in winning a debate with a few people, regardless of who you have to insult to win. At this point, my mental model of how your mind works is just about as interesting to me as my mental model of how EM waves work. The universe is full of strange and fascinating processes. But if you get back to physics, I will soon lose interest in your mind. |
Current across the antenna loading coil - from scratch
Cecil Moore wrote:
John Popelish wrote: I am making the point that if the displacement currents were insignificant, outside a coax, then the speed of light for waves out there would be infinite. And they are not, therefore those displacement currents cannot be assumed to be insignificant. But I am not talking about displacement currents within the transmission line, as exists in free space. I am talking *solely* about the displacement currents to *earth ground*. I contend that those are often secondary effects as proven by the coax example. Just how much displacement current to "earth ground" is there for a coil located halfway between here and Alpha Centauri? Almost exactly as much as there is between a coil that is a half wavelength from a grounded surface. Exactly the opposite. I am explaining the distributed effect of the E field along the wave. And completely ignoring the H-field? In the treatment of those fields, the only variation is Z0. For EM fields, there is no "across" and no "through". The difference between voltage and current essentially disappears except for their Z0 ratio. The equation for current in a transmission line is identical to the equation for voltage except for the Z0 term. Current "drops" are commonplace in lossy transmission lines. For instance, what is the current at the end of 200 feet of RG-58 terminated by a 50 ohm antenna used on 446 MHz when the source current is 2 amps? Somewhat less then 2 amps. Loss certainly occurs along that length, at that frequency? So what? Are you thinking that this is the predominate mechanism that is altering the current magnitude through your coil? It is part of the answer, but not the whole answer. You are avoiding the very facts that would allow you to make an air tight argument for your beliefs about "the whole point of the discussion". You somehow picture current as a continuous thing from one end of a conductor to the other, when it carries a traveling energy wave. This is a misconception. Maybe in the field of physics - not in the field of RF engineering. For any two current points, I can calculate a point in between. Sorry, but that's a characteristic of a *continuous* single-valued function and can be proven mathematically. I admit to being a EE/math major. I didn't take many pure physics courses so I am missing your point about me being able to prove anything additional. Maybe it will dawn on me after awhile. That is the best outcome I can hope for. What you don't get is, that the currents that each of those traveling waves would have generated were localized, to begin with. I realize that is the physicist talking and it agrees with my earlier assertion that standing wave current doesn't flow. No current flows. Charges flow (move) the magnitude of that movement past any point is current. I am picking nits, here, but the distinction is important if you want to build on these simple concepts. By the way, I am an EE, not a physicist, but I have to think physics to do engineering. I guess I'm so dense that I need help in proving what you think I can prove with that information. Right now, I am apparently missing something, maybe because of too much California Merlot. Sounds like something I might do, this afternoon. |
Current across the antenna loading coil - from scratch
John Popelish wrote:
Please forgive me for not recognizing which of the ten individual junk yard dog "experts" is biting my ankles at any particular time. :-) I am insulted that you include me in that derogatory characterization. I have been polite, patient and respectful with you in this discussion. It wasn't derogatory, John. It was a paraphrasing of the old saying: "When one is up to one's ass in alligators, it's hard to remember that the original purpose was to drain the swamp." But if you get back to physics, I will soon lose interest in your mind. I have no idea if "losing interest" is a good thing or a bad thing. -- 73, Cecil http://www.qsl.net/w5dxp |
Current across the antenna loading coil - from scratch
On Sun, 09 Apr 2006 18:57:55 GMT, Cecil Moore
wrote: Whatever way you choose to "take it" has absolutely no effect on any reality except your own personal reality existing only in your head. Enjoy! Odd you chose to deviate from technical discussion to explain "seeming" in terms of fornication and masturbation. You offer no quantifiables, and even more oddly, no qualifiables. Yours would be a pretty strange reality. |
Current across the antenna loading coil - from scratch
Cecil Moore wrote:
John Popelish wrote: The definition of "local" is wavelength dependent. Since the reality in which we exist has been proven to be non-local in nature, I'm wondering what is your point? Go back and ponder what I wrote. Too much has been clipped for my elaboration to have any continuity. Back to the RF case: Do you imagine that electrons from the source reach the load? Maybe for DC. But depending upon the length of the transmission line, probably not for HF RF. Is that a rhetorical question? It is a koan. Someone needs to tell that to W7EL. I've tried to tell him but instead of thanking me, he 'ploinked' me. Perhaps he has lost interest in this thread. Perhaps he is taking this topic personally. Perhaps he enjoys yanking your chain. Perhaps ... ... he is afraid of losing his "expert" status? What does any of that have to do with our conversation? Everything. That's what this thread is all about. I will repeat: Can the standing wave current phase, with its unchanging phase, be used to measure the phase shift through a wire or coil? That's the admittedly narrow present topic. The answer is either 'yes' or 'no'. After we answer that narrow technical question, the discussion can procede. I have answered with my opinion on that subject many times, already. I am trying to help you build your understanding of it, so you can argue it more persuasively, and understand it more completely. I'm doing it in public, to invite corrections from anyone who sees errors in my thinking, and can explain them to me. If you have no interest in anything but butting heads with the people who have disagreed with you, then, please stop responding to my posts. You have that choice. |
Current across the antenna loading coil - from scratch
Richard Clark wrote:
Odd you chose to deviate from technical discussion to explain "seeming" in terms of fornication and masturbation. You offer no quantifiables, ... Suffice it to say that at my age, the quantifiables are not what they used to be. :-) -- 73, Cecil http://www.qsl.net/w5dxp |
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