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Cecil,
What you are missing is the flux inside the coil links all the turns at light speed. When it does that, current appears at nearly the same instant of time (light speed over the spatial distance of the inductor) in all areas that are linked by flux. The flux coupling also tries to equalize currents throughout every area of the coil. Charge conservation also dictates that any current flowing into the coil has to be equalled by a like current flowing out the other terminal, less any displacement currents caused by stray capacitance (electric fields) to the outside world. We cannot have a two terminal "black box" with confined fields that behaves any other way, standing waves or not. The only flaws in having zero current phase shift and zero current difference are the less-than-perfect flux coupling and less-than-perfect confinement of the electric field. Any deviation from following perfect two-terminal rules are directly tied to the ratio of load impedance on the inductor to the stray capacitance to the outside world, and of course less than perfect flux linkage from end-to-end in the coil. People can often better understand the limits when things are taken to an extreme. Imagine a helical whip antenna. It is a very poorly constructed "loading coil". It has nearly infinite termination impedance at the open end, and very poor mutual coupling from turn to turn. The form factor is very distorted, far from being equal in diameter and length. The ratio of distributed capacitance to termination capacitance is very large, it can be nearly infinite. A loading inductor or helical whip like this behaves nearly like an antenna. The opposite would be a toroid, with a very compact form and almost total confinement of fields. Standing waves or not, as long as it is not near self-resonance it has evenly distributed current inside and at each terminal. Most well-designed efficient short antennas use a loading coil having very nearly equal currents at each terminal. Current equality actually is a good way to determine a properly designed loading coil. If you can stay on topic and we process only one point at a tme, I'm sure you will be able to learn how this works. If you see any flaw in how I just described inductor behavior, please point it out. Once we agree how an inductor works everything else will fall into place. 73 Tom |
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