The Wireless Power Transmission System
of Nikola Tesla
Oliver Nichelson
333 North 760 East
American Fork, Utah 84003
USA
onichelson@prodigy.net
http://pages.prodigy.net/onichelson
Copyright 1992
Historical Problems
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 frequencies [1,2].
Tesla, though, 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.
Non-Hertzian Transmission
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;"[3] and that
low frequency oscillations keep the "radiation of energy
into space in the form of hertzian or electromagnetic waves...
very small."[4] These two claims, alone, indicate a
technology different from today's.
The illustration 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. The published version of
the talk illustrates a setup for illuminating the bulbs closely
resembling the transmission configuration.
As he described it the evacuated bulbs were place between the
electrodes:
... when we excite luminosity in exhausted tubes the
effect is due to the rapidly alternating electrostatic potential;
… the medium is harmonically strained and released.[5]
He also noted:
…It might be thought that electrostatic effects are
unsuited for such action at a distance. It is true that
electrostatic effects diminish nearly with the cube of distance
from the coil, whereas electromagnetic inductive effects diminish
simply with distance. But when we establish an electro- static
field of force, the condition is very different, for then,
instead of the differential effect of both the terminals, we get
their conjoint effect.[6]
To make sure that the difference between the type of fields
he intended and those of Hertz was understood he explained:
…As the term electrostatic might imply a steady electric
condition, it should be remarked, that in these experiments the
force is not constant, but varies. When two conducting bodies are
insulated and electrified, we say that an electrostatic force is
acting between them.[7]
Tesla's emphasis on the non-Hertzian nature of his signaling
process, particularly when taken within the context of his work
with electrostatics, indicates the mode of propagation assumed by
the patent involves setting up an electrostatic field of force
between the transmitter and receiver.
As he often insisted, this mode of transmission differs
significantly from that of Hertzian waves in that this one is a
form of conduction:
…So far, I have considered principally effects produced
by a varying electrostatic force in an insulating medium, such as
air. When such a force is acting upon a conducting body of
measurable dimensions, it causes within the same, or on its
surface, displacements of the electricity, and gives
rise to electric currents ...[8]
He advocated such a form of signaling long before submitting
his design for patenting:
…Some enthusiasts have expressed their belief that
telephony to any distance by induction through the air is
possible. I cannot stretch my imagination so far, but I do firmly
believe that it is practi- cable to disturb by means of powerful
machines the electrostatic condition of the earth and thus
transmit intelligible signals and perhaps power.[9]
The physics of Tesla's wireless transmission system is, in
its basic form, is electrostatic induction.
Instead of a charged body inducing an opposite charge on an
uncharged body, as in the standard text book illustration, both
the transmitter and receiver contain charge that establishes a
field of force between the two. By oscillating these two bodies
of bound charge at the same frequency, it is possible to signal
between two points.
In order to differentiate Tesla's wireless method from
contemporary understanding of the technique, and from the
misunderstandings arising from the chronology of Tesla's research
into the nature of electrical communication, his method is
contrasted with modern patents for electrostatic submarine
communication and the inventor's earlier work in this field.
Contemporary Patents
L. Gilstrap's patent for an Electrostatic Communication
System, #3,964,051, issued June 15, 1976, describes a device
consisting of two concentric conducting spheres separated by a
dielectric layer to form a monopole radiator for electrostatic
waves.
The patent does not give details how "longitudinal
electrostatic or capacitive waves, also called scalar or
polarization waves because of their relationship to the Maxwell
wave equations" differ in their method of propagation from
conventional forms of electromagnetic radiation. It simply states
that as the spheres are subject to voltages of opposite polarity
the "outer sphere then appears as an ideal monopole radiator
to the external dielectric medium, in this case water."[10]
That this design was not effective, according to a report, is
due to the configuration of the radiator. The electric field is
confined to the region between the two conducting spheres. Little
energy, if any, is available to stress the external dielectric
medium, the water.
P. Curry's patent for an Underwater Electric Field
Communication System, #3,265,972, issued August 9, 1966
proposes a radiator of a different configuration and discusses
communications by electrostatic induction.
Curry states:
…The antenna system for an electromagnetic emission into
space circulates energy in accordance with the laws governing
electrical current in motion. Since the field strength produced
by an antenna is proportional to the alternating currents
circulating in it, its optimum structural relationships are
directed to a reduction of the total antenna resistance, thus to
increase the total current for a given power input to a radiator.[11]
Further on he adds:
…While a radiator for electromagnetic emission produces
its field strength by the effect of changing currents; the
radiator for electrostatic emission of the type here to be
described produces its field strength by the effect of changing
potentials.[12]
By applying a varying potential to the plates of the
radiator, charge of opposite polarity accumulates on the two
plates such that a charge gradient exists in the region between
the radiators. The patent explains:
... a phase displacement of 90 degrees exists the wave of
charge potentials induced by an alternating current signal upon
the water ... and the resulting wave of charge displacements
occurring in the water body between the segments.[13]
The method of propagation, then, is to cause electrical
changes in the two plates resulting in the launching into the
medium of sinusoidal carrier waves - as illustrated by the dotted
lines in Figure 5.
In a detailed analysis of forces involved Curry shows that
radiators with a capacitance of .0053 microfarads operating at
100 KHz with signal generator output of 200 volts coupled with a
biasing potential of 1000 volts will produce a force from its
charge displacement of 26,500 dynes.[14]
On the receiving side Curry states that the charge gradient
can be expected to attenuate substantially at even moderate
distance from the point of transmission. As an example he notes
that if a signal intensity of 10,600 dynes at the point of
transmission is reduced one billion times the "standing wave
of the signal energy will therefore be charged with a force
differential of 1.06 x 10-5 dynes. Each dipole having a
capacitance of .0053 microfarads produces a system capacitance of
.00265 microfarads. The voltage developed in the receiving
network is given by
e=square root (F/(C x 107)
which in this case equals .02 volts. As noted "this is
substantially above the minimum requirements of signal intensity
for the detection of electrical signal energies."[15]
With such a great amount of operational detail it would seem
that this design should perform as claimed. The device, however,
is not in widespread use 25 years after the issuing of the
patent. This forces the conclusion that the device did not
successfully propagate signals through the water. Why it would
not will be made clear by examining the Tesla design for wireless
communication. It will be shown that the dipole nature of the
radiator and the inability to state the amount of attenuation
over a given distance (it was simply given as a billion times
weaker than the transmitted signal) point to a fundamental
misunderstanding of the nature of electrostatic induction.
The shortcoming of the Curry design for an electrostatic
communication system can be seen in the basic nature relationship
existing between two points of charge.
Because lines of flux exist between two opposite charges a
dipole transmitting antenna is not needed. Curry proposed a
dipole in order to create a wave of the proper length to be
propagated through the medium. However, in electrostatics it is
not necessary for flux lines to detach and close upon themselves
to propagate an electric field. The field is established by the
flux lines between the two points of charge. Curry misunderstood
the nature of the electrostatic field. Once the field is
established, a change in pressure on the charge will cause a
variation in charge at the other end of the field - a
displacement current.
Also, Tesla points out that a dipole is not needed to receive
even low frequency signals in an electrostatic system. Tesla
pictured his receivers with electrodes spaced a quarter
wavelength apart but this was to charge an unpowered receiver as
rapidly as possible. The receiver's capacitor would see maximum
voltage changes, and, thus, would gain sufficient charge to power
a device, if the ground electrodes had such a spacing. If,
though, "the impulses are... are alternating, but
sufficiently long in duration" they can be received by a
single electrode that is turned on and off with the same period
as the transmitter. Because the field's flux lines do not radiate
but start at the transmitter and terminate on the receiver, the
receiving structure does not have to be a specific shape or
length.
His patent, then, also describes a through-the-earth, compact
ELF communication system. Today's ELF antenna arrays, by
contrast, require hundreds of square miles for their deployment.
Proof of Principle Test
This method of electrostatic communication can be tested by
using a grounded, resonant electrostatic detector coupled to a
standard communications receiver, encased in RF shielding to
receive a signal. For demonstration purposes a commercial station
transmitting on 1.16 MHz at 50KW, 40 miles away from the receiver
could be used as the test source.
If the transmitter's antenna is feed at 50ohms impedance, the
antenna current is:
The quarter wavelength period for 1.16 MHz is:
P = 1/4f
P = 1/(4)1.16x106
P = 2.16x10-7
sec.
The amount of charge in the antenna during the quarter period
is:
i = q/s and q = is
q = 31.6amps x 2.16 x 10-7 s
q = 6.8x10-6 coulombs
If 100 watts is assumed for the detector circuit, the current
at 50 ohms is:
I = square root (100/50) = 1.4 amps
and the charge:
q = 1.4 amps x 2.16 x
10-7 = 3 x 10-7 coulombs
Using Coulomb's law to calculate the force on each charge
separated by the given distance:
F=(q1q2)/(4p
e 0r2)
F=(3x10-7)(6.8x10-6)/(4p
(8.9 x 10-12)(6.4x104)2)
F = 4.5x10-12 nt. =
4.5x10-7 dynes
Assuming, finally, that the detector circuit uses a 100
microfarad capacitor, the force of the field will result in a
voltage as such:
e = square root (F/(C x 107))
e = square root ((4.5 x 10-7)/(100x10-6x107))
e = 21 x 10-6
A change of 21 microvolts would be well above the 5 microvolt
level required for a radio receiver to capture a signal from the
electrostatic detector circuit. It should be remembered, too,
that Tesia worked at higher energy levels than used in this
example. He used hundreds of amps at lower frequencies(more
charge) and potentials of millions of volts.
This analysis of Tesla's wireless transmission method is
preliminary, but does indicate the type of field of force and
distance calculations that have to be made in order to have a
successful electrostatic communication system. Issues dealing
with the optimum frequencies, the earth as a dielectric, and the
function of the earth's charge in power transmission have to be
investigated. This is in addition to the questions yet to be
discovered. However, it is clear that 100 years ago Nikola Tesia
began a branch of communication technology that differs
significantly from that in use today.
Notes
1. Wait, James R., "Propagation of ELF Electromagnetic
Waves and Project Sanguine/Seafarer," IEEE Journal of
Oceanic Engineering, vol. OE-2, no. 2, April 1977, pgs.
161-172.
2. Corum, James F., and Corum, Kenneth L., "Disclosures
Concerning the Operation of an ELF Oscillator," Tesla
'84: Proceedings of the Tesla Centennial Symposium, Dr.
Elizabeth Rauscher and Mr. Toby Grotz, editors, International
Tesla Society, Inc.. Colorado Springs, 1985, pgs. 41-49.
3. Tesla #787,412: page 1, lines 53 - 56.
4. Ibid., page 3, lines 35 -41.
5. Tesla, Nikola, "Experiments With Alternate Currents
of Very High Frequency and Their Application to Methods of
Artificial Illumination" (1891), reproduced in Nikola
Tesia: Lectures * Patents* Articles. published by the
Nikola Tesla Museum, Nolit, Beograd, 1956, pg. L-42.
6. Ibid.,pg. L-43.
7. ________, "On Light and Other High Frequency
Phenomena (1893), ibid., pg. L-121.
8. Ibid. L-127, emphasis added.
9. Ibid., pg. L-138.
10. Gilstrap: Column 2, lines 34-48.
11. Curry: Column 1, lines 21-28.
12. Curry: Column 1, lines 44-48.
13. Curry: Column 4, lines 8 - 38.
14. Curry: Columns 5-6.
15. Curry: Column 7, Imes 35 - 75 to column 8 line 2.
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