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Re: Tesla Coil RF Transmitter

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


Original poster: "Antonio Carlos M. de Queiroz" <acmdq@xxxxxxxxxx> 

Capacitive coupling decreases very fast with distance. It's the
"local field" of the antenna. Remember that both coils have
capacitance to ground, and this does not change significantly
if the coils are moved apart, while the capacitance between
the terminals decreases fast. The capacitance to ground of the
receiving coil and the capacitance between the terminals form
a capacitive voltage divider of huge ratio for quite small
distances. If the distance is comparable to the wavelength of
the transmitted signal, we have electromagnetic waves, far field.

According to the patent SYSTEM OF TRANSMISSION OF ELECTRICAL ENERGY and Tesla's article THE TRUE WIRELESS there is an interaction between the elevated terminals of the transmitting and the receiving stations. This interaction involves true electrical conduction and, in some cases, electrostatic induction. In operation the elevated terminal functions as one plate a capacitor. In opposition to the terminal are all other objects in the environment, including the receiver's elevated terminal. While more or less a majority of the field lines of a type-one transmitter are associated with nearby objects, some of them, according to Tesla's theory of operation, are associated with the elevated terminal of the other station. Tesla said,

   "The elevated terminal charged to a high potential induces an equal and
opposite charge in the earth and there are thus Q lines giving an average
current I = 4Qn which circulates locally and is useless except that it adds
to the momentum.  A relatively small number of lines q however, go off to
great distance and to these corresponds a mean current of I sub e = 4qn to
which is due the action at a distance.  The total average current in the
antenna is thus I sub m = 4Qn + 4qn and its intensity is no criterion for
the performance.  The electric efficiency of the antenna is q/Q+q and this
is often a very small fraction." [THE TRUE WIRELESS]

and

"The earth is 4,000 miles radius. Around this conducting earth is an
atmosphere. The earth is a conductor; the atmosphere above is a conductor,
only there is a little stratum between the conducting atmosphere and the
conducting earth which is insulating. . . . Now, you realize right away that
if you set up differences of potential at one point, say, you will create in
the media corresponding fluctuations of potential. But, since the distance
from the earth's surface to the conducting atmosphere is minute, as compared
with the distance of the receiver at 4,000 miles, say, you can readily see
that the energy cannot travel along this curve and get there, but will be
immediately transformed into conduction currents, and these currents will
travel like currents over a wire with a return. The energy will be
recovered in the circuit, not by a beam that passes along this curve and is
reflected and absorbed, . . . but it will travel by conduction and will be
recovered in this way." [Nikola Tesla On His Work With Alternating Currents and Their Application to Wireless Telegraphy, Telephony and Transmission of Power, pp. 128-130]

Many people live at more than a mile above sea level, and do not see
currents flowing through the air...

One does not have to live at a high elevation to see Saint Elmo's fire, lightning discharges, and the auroras.

A few hundred feet away, except for the irradiated energy. 

Tesla speculated about the illumination of an entire shipping lane, presumably
between New York and the southern coast of England, with the 'aurora
effect.'

The shape of the conductor, straight or coiled, does not make significant
difference in the far field generated. The total height of the system is
the most important factor.


I've been taught that with a base-loaded antenna the loading coil does not
contribute energy to the radiated field, only the straight section does
this.

. . . How the transmitter would be aware of the existence of a far receiver? . . .

The transmitter would be aware of the receiver in the exact same way as a generator does when an electrical load connected to it. In both cases there is a closed circuit through which current flows. In a complete type-one system using the "disturbed charge of ground and air method" the earth comprises one half of the circuit through which the high current associated with the transmitter's ground terminal flows. The other half of the circuit is the medium of the upper half space, i.e., the earth's atmosphere. Through this medium would flow the high voltage, low current energy associated with the transmitter's elevated terminal; I^2 R losses would be minimized. In a fully developed ultra high-power system operating in a push-pull mode it is conceivable the entire atmospheric path between the two stations would be ionized. And while charges don't necessarily flow freely in plasma, and the path resistance can be significant, all we are seeking to do is get fractionally more received energy than a conventional radio receiver gets from a conventional radio transmitter of equivalent power. Observing less of a reduction in signal strength than that which is predicted by the inverse-square law would be a significant experimental finding.

Best regards,
Gary