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There are a couple of problems with the analogy. First, of course, is
that there is no secondary winding to convert the primary's magnetic field to the current I you reference. The "aether" has no N and no I, and doesn't do this. The second problem is that a simple transformer model, or any other lumped-element circuit model, is valid only if its dimensions are very small compared to a wavelength(*). A mobile whip loading coil is often long enough that a current gradient can occur from one end to another, so a single lumped element model might be inadequate. Roy Lewallen, W7EL (*) A particular problem with the mobile loading coil in an electrically small whip is that the current changes a great deal over even a very short distance, as it goes from zero at the end of the whip (assuming no top loading) to a large value at the base. It sounds like sort of a circular argument, but a lumped element model loses accuracy any time there can be a current gradient across the component. Interestingly, the problem becomes less and less severe as top loading is increased, because it reduces the current gradient along the whip. You *could* quite accurately model a loading coil as a single lumped element if you had enough top loading. Art Unwin KB9MZ wrote: Yuri, I think you would better understand what is happening if you view the inductance in question as half of a transformer, where the other half is the aether. This allows you to bring in the formular NxI one side = NxI the otherside. This way you can see that I is constant. If it wasn't a constant then the lines of flux would have a very distorted shape at one end of the inductance. The fact that transformers have impedances that are not totally resistive is because of other factors than Inductance. If I am incorrect with this analogy I would apreciate any corrections as I am sure Yuri would to Art |
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