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Re: Tesla Coil RF Transmitter

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


Original poster: Paul Nicholson <paul@xxxxxxxxxxxxxxxxxxx> 

> 1.2 . . . In the case of this type transmitter, the transfer of
> electrical energy is between the two ground terminals in the
> form of true conduction currents, and also between the elevated
> terminals.


This is a radio wave by another name.  'true conduction current'
doesn't offer an alternative to EM waves for transferring energy. . . .

In the case of an operating Tesla-coil RF transmitting-receiving system using the ground and atmospheric conduction method, I agree that electromagnetic waves are involved. However, I do not believe these are "radio waves."

There is an electromagnetic field associated with the electrical current that flows through the earth between the ground terminal of the transmitter and the ground terminal of the receiver. As with any electrical transmission line there are loops and nodes or maxima and minima in the EM field, distributed along the conductor, the distance between which corresponds to the wavelength of the transmitted energy. Some of the energy of this ground current and its associated EM field escapes from the system in the form of "radio waves." I use this term "radio waves" in its narrowest sense, i.e., far-field electromagnetic waves that have closed back upon themselves and are no longer associated with the launching structure. These "radio waves" that are more than one wavelength from the launching structure, and have their E and H components in phase are the "Hertz waves" to which Tesla occasionally refers in his writings. These "radio waves" have nothing to do with the transmission of energy through the earth between the transmitting and receiving stations other than in the fact that they constitute a mechanism for loss from the overall resonating system.

In addition to the alternating electrical current flowing through the ground, there is also a flow of electrical energy between the elevated terminal of the transmitter and that of the receiver. This occurs as a combination of displacement current between the respective elevated terminals and the conducting upper atmosphere beginning at about 7.5 kilometers up, and electrical conduction through the conducting region spanning the distance between the two locations. (Taking into account the powerful magnetic field developed by each station's helical resonator, an embedded magnetic field might also be involved.) While not an ohmic conductor, the density or pressure of the upper atmosphere is sufficiently reduced so that it's insulating properties can be impaired, allowing the electric current to flow. The conducting region is developed through the process of atmospheric ionization, in which the effected portions of the atmosphere are modified to the plasma state. Tesla wrote about the possibility of using powerful ionizing beams pointing upward from the elevated terminals to ionize the atmosphere directly above the stations, leading to a flow of conduction currents between the two terminals by a path up to and through the troposphere, and back down to the other station. As with the terrestrial transmission line mentioned above, EM waves are also associated with the atmospheric transmission line as well. Because plasma is the conducting medium, these are either electrostatic plasma waves or, assuming the presence of inter-connected magnetic fields, magneto-hydrodynamic plasma waves. Note that propagation of an ion acoustic wave in plasma bears a distinct resemblance to Tesla's description of "the universal medium . . . a gaseous body in which only longitudinal pulses can be propagated, involving alternating compressions and expansions similar to those produced by sound waves in the air."

It matters little if the two TC ground terminals
are joined together or not by a common 'earth'.


Actually, it makes all the difference in the world.

The best method for transmitting power by EM waves is to guide it
to its destination, using . . . a pair of wires - such as a mains cable. . . .

Yes, a pair of conductors is the best way to go, and that's exactly what Tesla had in mind with the ground and atmospheric conduction method:

"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 . . . will be immediately transformed into conduction currents, and these currents will travel like currents over a wire with a return. . . ." -- Nikola Tesla, 1916

Paul Nicholson 

Gary Peterson