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RE: Calculating secondary resonance of bipolar coils



Original poster: "Terry Fritz" <twftesla-at-uswest-dot-net>

At 08:28 AM 1/11/2001 +0000, you wrote:
snip...
>
>> However, one particular frequency will have the maximum amplitiude.
>> Isn't this the resonant frequency? and if this is Fr, where are the
>> harmonics?
>
>The apparent 'amplitude' of the resonance will be determined by how
>much power is coupled into the coil from the generator. This is likely
>to appear greatest at the lowest resonant frequency, ie the usual
>one for TC operation. This is because the lowest mode exhibits the
>lowest input impedance for a given coil and coupling method.
>
>I'll qualify that statement slightly. If you're picking up the coil
>activity using a 'plane wave antenna' as static field pickups are
>often inappropriately called, the response of such a pickup can rise
>with frequency at up to 6dB per octave due to the capacitive nature of
>its pickup - its a CR network, the C being the capacitance between
>pickup and coil, and R the input resistance of your detector. 
>A similar thing occurs with inductive loop pickups, the loop output
>voltage being proportional to frequency.  With this in mind, the
>higher modes may sometimes appear to have more amplitude than they
>really have.
snip...
>Cheers
>--
>Paul Nicholson,
>Manchester, UK.
>--
>

I should mention that the above frequency response problem my be true for
wires off scope probes.  However, E-field antenna's like the one I describe
below use c:c dividers for voltage and r:r dividers for current in such a
way as to give a flat frequency response.  This is discussed in the paper too.

http://hot-streamer-dot-com/TeslaCoils/MyPapers/planant/waveant3.html

Cheers,

	Terry