Re: Tesla Coil RF Transmitter

["Tesla list" <tesla@xxxxxxxxxx>]

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.