Tesla described his wireless power transmission method
by three characteristics: 1) the reduction or elimination of electromagnetic
radiations, 2) that it operated through the earth, and 3) that
the mechanism of transmission is an electric current - as contrasted
with radiations. Modern analysts, on the other hand, model Tesla's
transmission system on present day broadcast radio technology.
This model assumes an antenna propagating electromagnetic waves
into the air where these radiations either will not or will, depending
on the presuppositions of the writer, bring about the effects
claimed by the inventor.
Anachronistic interpretation - applying the assumptions
of today's electrical theories to Tesla's original turn of the
century researches - is only half the problem of understanding
the inventor's wireless method. The situation is further complicated
by the similar sounding descriptions Tesla gave to his earlier
and later transmission techniques.
In his early work Tesla attempted electronic transmission
by modifying the atmosphere. This is the case in his patent entitled
Method of Intensifying and Utilizing Effects Transmitted Through
Natural Media, #685,953, applied for in June 1899. In this patent
he proposes a very powerful signal generator to ionize atmospheric
gases and, by that, create a conductive path between the transmitter
and receiver through which a current could be sent. Later, when
Tesla disclosed what he described as through-the-earth (or water)
transmission with essentially the same type of apparatus and operating
at ELF frequencies, it has been assumed by modern authorities
that Tesla was mistaken about his method of propagation and was
really witnessing earth-ionosphere cavity resonance at Schuman
was more than an engineer of conventional methods. He was an electrical
researcher who investigated fundamental issues of the science.
It will be shown that the three characteristics of Tesla's wireless
transmission system describe an electrostatic wireless method
that used the earth as a conductor and transmitted displacement
currents. At moderate power levels the system could
be used for communication. At greater levels, power could be sent by wireless.
During 1899 - 1900 Tesla set up a laboratory in Colorado
Springs to investigate wireless signal transmission. It was during
this period he discovered that a properly configured receiver
could detect waves, initiated by lightning strikes, propagating
through the earth. When he incorporated this discovery into a
patent he differentiated the earlier technology dealing with "effects
transmitted through natural media" from the new form of signaling
that involved the transmission of energy. This is seen in his
patent Art of Transmitting Electrical Energy Through the Natural
Mediums, #787,412, applied for 11 months after the previous patent,
in May 1900.
A great deal of detail about the apparatus for generating
and receiving electrical signals (tuned resonant circuits that
were recognized in 1943 by the Supreme Court as the basis of commercial
radio designs) is given in the patent but it assumes,
or more likely, avoids revealing, the physics behind the mode
of propagation. Tesla does point toward his novel transmission
technique when he notes in the patent that the "globe may
... behave ... as a conductor of limited size;" and that
low frequency oscillations keep the "radiation of energy
into space in the form of hertzian or electromagnetic waves...
very small." These two claims, alone, indicate a technology
different from today's.
The illustration (see Figure
1 on the next page)for the
patent is of a transmitter consisting of an elevated capacitance,
a coil, a signal generator, and a single electrode in the earth.
The receiver is pictured as having a mechanism to oscillate at
the same period as the transmitter, a capacitor, a detector, and
two earthed plates.
To understand Tesla's wireless
transmission system it is necessary to look at his technical writings
on the physics behind his engineering. One of his lectures on
evacuated tube illumination provides a good example.