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Re: Tesla Coil RF Transmitter



Original poster: "Gary Peterson" <gary@xxxxxxxxxxxx>


Original poster: Jim Lux <jimlux@xxxxxxxxxxxxx>

A couple problems:
1) that wavelength thing... It assumes uniform
propagation speed, which is hardly the case,
particularly for propagation over a boundary.

The velocity of the disturbance in Earth's charge is not constant as it travels over its surface. It falls as the distance from the transmitter increases, up to the half-way point, and then it increases back to its initial velocity as it reaches the antipodes.


2) The earth isn't a smooth uniform sphere,
so the paths aren't symmetric

For a Tesla-coil transmitter located on the equator, at least the east-west axis is symmetrical. If Tesla's preferred transmitter design is used (see CSN, p. 200, Fig. 6), with both transmitting elements positioned exactly at that latitude, the induced disturbance will be in predominantly east and west directions.


3) Sufficiently powerful transmitter doesn't
have much to do with it, although that will
affect the detectability.

A well grounded Tesla-coil transmitter has to apply about 75,000 watts "to keep the earth vibrating so long as there is no energy taken out at any other place."


4) There's no reflection at the antipodes
(which doesn't really exist anyway,
because of #1 and #2), the wave just
keeps on going and eventually gets
back to the start.

Of course there is a corresponding antipode to every point on Earth's surface; the validity of #1 and #2 make no difference. The question is, will the arrival of the disturbance from every direction coincide. Given that Earth is not a uniform sphere, the answer must be no. By placing the transmitter on the equator, as described above, the situation improves. The ideal placement for purposes of mathematical modeling is on the North or South Pole.


The latter effect is widely noted as "long path"
propagation on radio transmissions.  You
get two copies of the transmitted signal,
separated in time by the differential propagation
delay for the short way and long way.

Of course we're not discussing wireless transmission by radio waves. The subject of this thread has boiled down to the wireless transmission of electrical energy by the "disturbed charge of ground and air method" (CSN, p. 29).

In any case, the propagation around the earth (at whatever frequency) is
sufficiently non-uniform and lossy that you're not going to get any
significant standing waves.  No "ringing like a bell"

The production of insignificant standing waves would be better than none at all.