Re: Tesla Coil RF Transmitter

["Tesla list" <tesla@xxxxxxxxxx>]

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

Tesla list wrote:

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

> 1.2 There are two additional types of wireless transmitter that you 
> can build using a Tesla coil.  The first is quite similar to the 
> classic Tesla coil that nearly everyone on this list has 
> assembled.  The main difference is in the placement of the 
> topload.  Instead of mounting it close-in  just above the 
> resonator's top turn, the topload is elevated somewhat above the top 
> turn.  Unlike the radio transmitter described in paragraph 1.1, this 
> transmitter requires that a precisely tuned helical resonator type 
> receiver be set in place in order for it to function.
> This is why in the related wireless patents Tesla always shows both 
> the transmitter and the receiver (see 
> http://www.teslaradio.com/images/645576-1a.gif for example).  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.  In a low power 
> system, the transfer of energy between the elevated terminals is, in 
> effect, the result of displacement currents, much like the transfer 
> of electrical energy which takes place between the plates of a 
> capacitor in an AC circuit.  I call this the type-one transmitter.
> 1.3 The second of the Tesla-type transmitters consists of a type-one 
> transmitter plus an unloaded helical resonator receiver, both placed 
> in close proximity to each other, each with an independent ground 
> connection. Tesla first illustrates the improved type-two 
> transmitter in his Colorado Springs laboratory notes (see 
> http://www.teslaradio.com/images/csn-200-6a.gif for example).  The 
> two illustrations at http://www.teslaradio.com/images/image004.jpg 
> and http://www.teslaradio.com/images/TS-261-1a.gif  show type-two 
> transmitters in operation.  In operation, a powerful current flows 
> through the earth between the two ground terminals.  The coupling 
> between the transmitter's two elevated terminals is by electrostatic 
> induction or, in the case of a high-power transmitter, by true 
> electrical conduction through plasma.  There is also some degree of 
> inductive magnetic coupling between the two helical resonators.  The 
> type-two transmitter is particularly well suited for exciting earth 
> resonance modes.  I think it's interesting to see that in the 
> related patent ART OF TRANSMITTING ELECTRICAL ENERGY THROUGH THE 
> NATURAL MEDIUMS, Tesla shows a form of receiver that does not 
> involve a helical resonator.

These may have been the ideas that Tesla had about radio transmission,
but both have serious problems, to not say that they are wrong:

The idea of conducting current through the air is simply unworkable.
Tesla's idea of using a very elevated terminal is of completely
inviable construction, and would not work anyway, because the line
going to the elevated terminal would work as an antenna, and irradiate
most of the power. Unless the system worked at a very low frequency.
But then, back to the construction problems and huge losses.

The idea of transmission through the ground falls back into a vertical
monopole, a very standard type of antenna. What it irradiates depends
essentially on the vertical length of the system, mo matter how the wire
is coiled, what type of topload, etc. These determine only the frequency
of the transmitted signal. If the length of the system is much smaller
than the corresponding 1/4 wave length, very little energy is
irradiated. The high current going into the ground doesn't mean
anything. It just returns to the terminal by displacement current
after moving just a bit away from the ground connection, without
producing significant electromagentic waves. The whole system is
almost purely reactive.

Antonio Carlos M. de Queiroz