Re: Tesla Coil RF Transmitter

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: Paul Nicholson <paul@xxxxxxxxxxxxxxxxxxx>

Gary Peterson quoted:

> [Nikola Tesla, 1916] The earth is 4,000 miles radius...

Thanks for the well-chosen quote, Gary.  I think it clearly
shows the fundamental error of principle which Tesla was
making.   He thought the 'pumped' charge would be uniformly
distributed around the globe, which is wrong.    He took the
hydraulic analogy too far, and failed to realise that the
charge distributes itself in accordance with the field of
the transmitter.

Put another way, he was treating the earth as if it where a
spherical terminal of a capacitor - with the other terminal
at infinity.   But in reality, the 'other terminal' would be
his topload and coil, and the 'pumped' charge would be confined
to their vicinity.

The only way to rescue the situation would be to use the
transmitting TC to excite a global resonance, which, if the
Q factor were high enough, would allow the transmitter's near
field to extend out to cover the globe, and thus provide
an opportunity for receivers to couple to the field.  In this
scenario, stored energy would cycle between the cavity and
the transmitter.

For this to work, the global resonance must have a very high
unloaded Q factor because of the feeble coupling between the
cavity and any realistically sized transmitter.

Some have claimed that the Schumann resonances do in fact have
a high Q factor, whereas all scientific research on the matter
points to Q factors of around 6-12.  For example, Gary quoted:

> [1988 Sutton/Spaniol paper]
> The Q values measured are of the order of 100-2000, limited by
> the resolution of the analyzer.

This is a very suspicious claim, and I would have to see the whole
paper to identify their errors.  The suspicion arises because no
researchers, before or since, specialising in that field, have
reported anything like such high Q factors.   These days it is
quite easy for amateurs to detect these resonances themselves
with sufficient S/N ratio such that a frequency modulated high Q
resonance would be most obvious.   For example, the apparent
bandwidth would vary systematically with integration time,
and with short integration times (order 10 secs) the high Q
resonance would make a clear 'line' on a spectrogram, rather than
the broad band of noise that we actually get.
--
Paul Nicholson
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