Re: SSTC As a transmitter.

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Jim Lux by way of Terry Fritz <twftesla-at-qwest-dot-net>" <jimlux-at-earthlink-dot-net>



> > During the '70s some radio amateurs were keen on what they called
> > 'earth mode' communications, which basically involved pumping lots
> > of LF power circa 20kHz into the ground, using two electrodes set
> > into the ground quite some distance apart.  The receiver uses
> > a similar pair of electrodes to pickup up the differential voltage
> > due to the current field in the earth excited by the transmitter.
> > As you can imagine the signal strength falls off very rapidly with
> > range.
> 
> There are people still doing that.  I think 4 or 5 miles is considered a
> good result.

This is basically a simple application of Ohm's law in a volume media.
It's a common way of doing geophysical exploration: resistivity surveying.
 Nothing special going on here.. It's just basically a big resistive divider.

> 
> My primary interest is in energy transmission for telecommunications
> purposes.  Geophysical exploration also rates high on the list.

There is a fairly good elementary and intermediate literature on the web on
the Geophysical exploration end of things (do a search for things like
"Electrical Resistivity Surveying",Electromagnetic Prospecting", or
"Electrical Resistance Tomography").  There's a web site at the Univ of
Colorado (I think) School of Mines which has what is essentially an online
textbook on all the various ways this stuff is done.