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Current through coils
Roy Lewallen wrote:
If, however, you look at the currents in and out of the *network* you'll see that they're different, because of current going to ground through the C. The main effect in a standing wave environment are the forward and reflected phasors rotating in opposite directions. The standing wave current is ZERO when those phasors are 180 degrees out of phase. The standing wave current is maximum when those phasors are in phase. "Current going to ground through the C" is not even required. But with zero length, there can be no standing waves inside the inductor. You keep saying stuff like this as if a zero length inductor actually existed in reality. Wake up, Roy, and smell the roses. That zero length inductor exists only in human minds. When you look at the currents reported by EZNEC for the model on Cecil's web page, the current at the top of the coil is the equivalent to the *network* current described above. It's the current flowing through the inductance minus the current being shunted to ground via the C between the coil and ground. Huh? How do you explain the current at the top being greater than the current at the bottom of the coil? Is the coil sucking current from the ground? -- 73, Cecil http://www.qsl.net/w5dxp |
Current through coils
Cecil Moore wrote: Roy Lewallen wrote: If, however, you look at the currents in and out of the *network* you'll see that they're different, because of current going to ground through the C. The main effect in a standing wave environment are the forward and reflected phasors rotating in opposite directions. The standing wave current is ZERO when those phasors are 180 degrees out of phase. The standing wave current is maximum when those phasors are in phase. "Current going to ground through the C" is not even required. That's utter nonsense Cecil, and why people aren't buying into your misconceived theories. Maybe you can take some time to rethink your position while on vacation. A two-terminal network that transforms impedance, now there's a concept! An inductor behaves exactly the same way in or out of your so-called standing wave environment. It follows the same rules all the time. Since your theory says otherwise, it has to be wrong. Wave theory is just another way of analyzing a complex system. It doesn't change how things inside the system behave. 73 Tom |
Current through coils
Cecil Moore wrote: wrote: The point I (and others) tried to make was that in a small inductor current was essentially equal at both ends of the coil, ... A 75m bugcatcher coil is NOT a small inductor. It is a slow- wave structure with a velocity factor of about 0.017, both measured and calculated. That gives my bugcatcher coil an electrical length at 4 MHz of about ~60 degrees. Let's focus on one thing at a time. You claim a bug cather coil has "an electrical length at 4MHz of ~60 degrees". That concept is easily proven false, just like the claim a short loaded antenna is "90-degree resonant". Both can be shown to be nonsense pictures of what is happening. Assume I have a 30 degree long antenna. If the loading inductor is 60 electrical degrees long, I could move it anyplace in that antenna and have a 90 degree long antenna. We all know that won't happen, so what is it you are really trying to say? 73 Tom |
Current through coils
Cecil Moore wrote:
Ian White GM3SEK wrote: You see a larger picture of the whole antenna, so you can choose many different ways to theorize about it. But your theory cannot be correct if it requires that components behave in different, special ways according to the way you happen to be thinking about it at the time. Inuendo devoid of any technical content, Ian? Precisely and specifically NOT that! Let me have one last try: The human observer sees a larger picture of the whole antenna, and can choose many different ways to theorize about it. But a theory cannot be correct if it requires that components behave in different, special ways according to the way a person happens to be thinking about it at the time. If you cannot see that statement as a fundamental principle of scientific logic, then I have run out of ways to tell you. Replacing the part of my previous message that you snipped: Electronic components... have no conception of traveling or standing waves. They react simply to the voltages and currents they experience at their terminals. They cannot behave in different ways for different types of current. If you want to analyse the current into different parts and give them different labels, a pure, lumped loading inductance MUST still respond to every kind of current in the same way. It is not my theory. It is the distributed network model which you apparently reject. No, I reject your incorrect applications. The reasons may look simple but they are absolutely fundamental. -- 73 from Ian GM3SEK 'In Practice' columnist for RadCom (RSGB) http://www.ifwtech.co.uk/g3sek |
Current through coils
Ian White GM3SEK wrote:
Precisely and specifically NOT that! :-) "My theory"? It's not my theory. Components behaving differently? No. Special ways according to my thinking? Of course not. There's nothing special. The "special magic thinking" is yours in thinking that standing wave current is the same as traveling wave current. If you cannot see that statement as a fundamental principle of scientific logic, then I have run out of ways to tell you. I see your statement for exactly what it is, Ian, full of inuendo and ignorance of the nature of standing wave current. Have you no clue what func(kx)*func(wt) really means? It is not my theory. It is the distributed network model which you apparently reject. No, I reject your incorrect applications. You reject the distributed network analysis because you are completely technically ignorant of the nature of standing wave current. -- 73, Cecil http://www.qsl.net/w5dxp |
Current through coils
wrote:
You claim a bug cather coil has "an electrical length at 4MHz of ~60 degrees". That concept is easily proven false, just like the claim a short loaded antenna is "90-degree resonant". Both can be shown to be nonsense pictures of what is happening. Well, I've been challenging you to do just that for weeks now and so far, nothing. Please note the contradiction between your statement above which says an antenna doesn't have to be 90 degrees long to be resonant and your statement below which says it does. Would you please make up your mind? Assume I have a 30 degree long antenna. If the loading inductor is 60 electrical degrees long, I could move it anyplace in that antenna and have a 90 degree long antenna. This again demonstrates your misconceptions. Please pay attention this time. When my 75m bugcatcher coil is configured as a base-loaded coil with a 7 foot whip, it occupies ~60 degrees of antenna. The 7 foot whip occupies ~10 degrees of the antenna. The total length is only ~70 degrees, not 90 degrees. That 90 degrees is just your strawman and you even contradicted yourself above. The antenna doesn't have to be 90 degrees long. What has to happen is for (Vfor+Vref)/(Ifor+Iref) to be resistive at the feedpoint. There are many possibilities for that in antennas not 90 degrees long. I gave one such example possibility weeks ago. Perhaps you missed it. I haven't measured the number of degrees occupied by a center- loaded 75m bugcatcher coil. Since the inductance of the center-loaded coil must be increased when moved from the base to the center, it would occupy more of the antenna at the center than it does at the base for the same resonant frequency. The 70uH 75m bugcatcher coil occupies ~60 degrees when installed at the base. For the same resonant frequency and same length for the rest of the antenna, a center-loaded coil would need about double that reactance, making it about 1.4 times the size of the base-loaded coil. So I would estimate that the center-loaded coil is occupying ~80 degrees of the antenna, much closer to a total of 90 degrees than the base-loaded version. -- 73, Cecil http://www.qsl.net/w5dxp |
Current through coils
Cecil Moore wrote:
Ian White GM3SEK wrote: Precisely and specifically NOT that! :-) "My theory"? It's not my theory. Components behaving differently? No. Special ways according to my thinking? Of course not. There's nothing special. The "special magic thinking" is yours in thinking that standing wave current is the same as traveling wave current. If you cannot see that statement as a fundamental principle of scientific logic, then I have run out of ways to tell you. I see your statement for exactly what it is, Ian, full of inuendo Let us repeat the statement, then: The human observer sees a larger picture of the whole antenna, and can choose many different ways to theorize about it. But a theory cannot be correct if it requires that components behave in different, special ways according to the way a person happens to be thinking about it at the time. That statement was not innuendo at all. It means nothing more than what it literally says. It applies to any and every observer who attempts to construct a theory about something. Everybody is included; but nobody is exempt. and ignorance of the nature of standing wave current. Have you no clue what func(kx)*func(wt) really means? It is not my theory. It is the distributed network model which you apparently reject. No, I reject your incorrect applications. You reject the distributed network analysis because you are completely technically ignorant of the nature of standing wave current. That is a close to perfect mirror-image of my views on the positions you take. The difference is that my views join up with the rest of human knowledge about antennas and circuit behaviour. Yours don't. They fail that crucial test. -- 73 from Ian GM3SEK 'In Practice' columnist for RadCom (RSGB) http://www.ifwtech.co.uk/g3sek |
Current through coils
Cecil,
Well, I guess it's back to the math books for me. I mistakenly thought that currents described by cos(kz-wt) and cos(kz).cos(wt) would be considered "instantaneous" currents. If they're really RMS, well . . . I am curious about one thing, however. It would seem that all of this "averaging", "RMS", and "net" is a bit inconsistent with digging into a distributed network problem, which you insist is the only valid description. Everything can vary in time and space in a distributed network. Certainly these consolidating functions are useful for a general overview, but how can you learn anything about the details of a complex system by averaging and netting? 73, Gene W4SZ Cecil Moore wrote: Give us a break, Tom. Of course, we are *NOT* and never have been talking instantaneous currents. All currents ever discussed concerning this subject have been RMS currents. That's just your instantaneous strawman. Long term charge accumulation is averaged over many cycles. There is simply none of that because the traveling waves are not storing any net charge inside the coil. How can you get so desperate as to play such silly games? My statement obviously meant: One amp of RMS forward current is flowing into the coil and one amp of RMS forward current is flowing out of the coil. Average charge is balanced. Even though the standing wave current is different at each end of the coil, the average charge into and out of the coil is still balanced. |
Current through coils
Ian White GM3SEK wrote:
That statement was not innuendo at all. It means nothing more than what it literally says. It applies to any and every observer who attempts to construct a theory about something. Everybody is included; but nobody is exempt. It means the lumped-circuit model works where the distributed- network model fails. That is false. It is just the opposite. the distributed-network model works where the lumped-circuit model fails. The difference is that my views join up with the rest of human knowledge about antennas and circuit behaviour. Only up to where the coils are 15 degrees long. Then the distributed network model must be engaged to avoid blunders exactly like you and others are making. Yours don't. They fail that crucial test. Distributed network analysis fails the test??? Please provide an example. The IEEE would probably publish a paper on such. -- 73, Cecil http://www.qsl.net/w5dxp |
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