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Re: That secondary behaviour, E-Tesla5, and Corum's thing...
Hi:
Apparently now we all agree that a lumped model models very well
what happens up to the first resonance or a coil.
Since several of you are now playing with coil resonances, I can
return to a topic that I mentioned a few times in the past:
A long vertical coil is a rather nonuniform transmission line.
An ideal transmission line would have resonances at frequencies
f0, 3f0, 5f0, 7f0,... My experiments with coils indicate that
the resonances of a typical coil appear shifted to low frequency
in relation to what would appear in an ideal transmission line.
Can someone verify this?
Another curious experiment is to see what happens with the extra
resonances with a terminal is added to the coil. The first resonance
goes to lower frequency, as expected, but the other resonances also
shift to lower frequency. In an ideal transmission line, they would
approach 2f0, 4f0, 6f0,..., where f0 is the frequency of the first
resonance without terminal. The reason is that the coil starts to
behave as if the terminal end were grounded, by effect of the
terminal capacitance.
Antonio Carlos M. de Queiroz