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The World Wireless system was Tesla's proposed global system "for the transmission of electrical energy without wires" intended for point-to-point wireless telecommunications, broadcasting, and the demonstration of wireless power on a greatly reduced scale.  The idea was first broached in a June 1900 Century Illustrated Magazine article titled "The Problem of Increasing Human Energy" although planning began prior to 1899.  The system was to depend upon the high electrical conductivity of the earth. With the initial financial backing of banker J. P. Morgan, construction started in 1901 of the Wardenclyffe Tower, the first part of this system.  The venture failed due to insufficient funding.  The plant was not completed, bankrupting Tesla and ending his plans for a world wireless system.

Transmission of electrical energy

An electric current flowing through a conductor carries electrical energy.  The body of the earth is an electrical conductor, nearly spherical in shape, insulated in space.  It possesses an electric charge relative to the upper atmosphere beginning at an elevation of about 50 kilometers.  When a second body, directly adjacent to Earth, is charged and discharged in rapid succession this causes an equivalent variation of Earth's electrostatic charge, resulting in the passage of electric current through the ground.

The grounded resonance transformer electrical oscillator transmitter, both the single and dual tower forms, is an electrical machine specifically designed to create a displacement of Earth's electric charge.  This is done by alternately charging and discharging the oscillator's elevated terminal capacitance at a specific frequency, generating an alternating electric field, and periodically altering the electrostatic charge of Earth, and consequently, with sufficient power, the electrical potential over its entire surface.  "A connection to earth, either directly or through a condenser is essential." The placement of a grounded resonance transformer electrical energy receiver tuned to the same frequency as the transmitter at another point on the surface results in the flow of electric current through the earth between the two, "while an equivalent electric displacement occurs in the atmosphere." This current can be used at the receiver to drive an electrical load.  In the case of an individual World Wireless Telecommunications System receiver this would be a sensitive device using only a small amount of energy.

In 1891 and 1892, Tesla used the oscillatory transformer that bears his name in demonstration lectures delivered before meetings of the American Institute of Electrical Engineers (AIEE) in New York City" and the Institution of Electrical Engineers (IEE) in London. Of two significant results that were demonstrated, one was that the wireless transmission of electrical energy is possible.  A later presentation, titled "On Light and Other High Frequency Phenomena" (Philadelphia/St. Louis; Franklin Institute in 1893), is a key event in the invention of radio and can also be said to have begun the development of the Wardenclyffe World Wireless System facility prototype.

One-wire transmission

In the early presentations, the first experiment to be demonstrated was the operation of light and motive devices connected by a single wire to only one terminal of a high frequency induction coil, performed during the 1891 New York City lecture at Columbia College.  While a single terminal incandescent lamp connected to one of an induction coil’s secondary terminals does not form a closed circuit “in the ordinary acceptance of the term” the circuit is closed in the sense that a return path is established back to the secondary by capacitive coupling or 'displacement current'.  This is due to the lamp’s filament or refractory button capacitance relative to the coil’s free terminal and environment; the free terminal also has capacitance relative to the lamp and environment.  At high frequencies, the displacement current through these capacitances is sufficient to light the lamp.

Wireless transmission

The second result demonstrated how energy can be made to go through space without any connecting wires.  This was the first step towards a practical wireless system.  The wireless energy transmission effect involves the creation of an electric field between two metal plates, each being connected to one terminal of an induction coil’s secondary winding.  Once again, a light-producing device (in this case a gas discharge tube) was used as a means of detecting the presence of the transmitted energy.  "The most striking result obtained" involved the lighting of two partially evacuated tubes in an alternating electrostatic field while held in the hand of the experimenter.

Two different types of wireless transmitter were described, both employing a high-tension induction coil.  One has a sheet of metal suspended from the ceiling and connected to one of the induction coil’s terminals, with the other terminal being connected to ground.  The other type of transmitter has two sheets of metal suspended from the ceiling, each being connected to one of the coil’s high-voltage terminals.

Wireless transmission and reception

Early experiments toward development of a world wireless system involved the propagation of ordinary radio waves, that is to say Hertz waves, unguided electromagnetic waves propagated through space.

The popular impression is that my wireless work was begun in 1893, but as a matter of fact I spent the two preceding years in investigations, employing forms of apparatus, some of which were almost like those of today.  It was clear to me from the very start that the successful consummation could only be brought about by a number of radical improvements.  Suitable high frequency generators and electrical oscillators had first to be produced.  The energy of these had to be transformed in effective transmitters and collected at a distance in proper receivers.  Such a system would be manifestly circumscribed in its usefulness if all extraneous interference were not prevented and exclusiveness secured.  In time, however, I recognized that devices of this kind, to be most effective and efficient, should be designed with due regard to the physical properties of this planet and the electrical conditions obtaining on the same.

One of the requirements of the World Wireless system is the construction of resonant receivers. The grounded helical resonator of a Tesla Coil and an elevated terminal can be used in receive mode.  In the principle form of Tesla system receiver, a Tesla coil receiving transformer acts as a step-down transformer with high current output. The parameters of a Tesla Coil transmitter are identically applicable to it being a receiver (e.g.., an antenna circuit), due to reciprocity. Tesla repeatedly demonstrated the wireless transmission of electrical energy from a Tesla coil transmitter to a Tesla coil receiver.  These concepts and methods are part of his wireless transmission system (U.S. Patent No. 1,119,732, Apparatus for Transmitting Electrical Energy, January 18, 1902, December 1, 1914).  He made a proposal that there would be many more than thirty transmission-reception stations worldwide.

In another form of receiving circuit the two input terminals are connected to a device designed to reverse polarity at predetermined intervals of time and charge a capacitor. This form of Tesla system receiver has means for commutating the current impulses in the charging circuit so as to render them suitable for charging an energy storage device, a device for closing the receiving-circuit, and means for causing the receiver to be operated by the accumulated energy.

The intention of the Tesla world wireless energy transmission system is to combine broadcasting and point-to-point wireless telecommunications along with electrical power transmission, allowing for the elimination of many existing high-tension power transmission lines, facilitating the interconnection of electrical generation plants on a global scale.

Wardenclyffe was the first of many installations to be constructed near major population centers around the world.  If plans had moved forward without interruption the Long Island prototype would have been followed by a second plant built in the British Isles, perhaps on the west coast of Scotland near Glasgow.  Each of these facilities would include a large magnifying transmitter of a design loosely based upon the apparatus assembled at the Colorado Springs Experimental Station in 1899.

"The plant in Colorado was merely designed in the same sense as a naval constructor designs first a small model to ascertain all the quantities before he embarks on the construction of a big vessel.  I had already planned most of the details of the commercial plant, subsequently put up at Long Island, except that at that time the location was not settled upon.  The Colorado plant I have used in determining the construction of the various parts, and the experiments which were carried on there were for the practical purpose of enabling me to design the transmitters and receivers which I was to employ in the large commercial plant subsequently erected."

Theory of wireless transmission

While working to develop an explanation for the two observed effects mentioned in the 1891 and 1892 lectures, Tesla recognized that electrical energy can be projected outward into space and detected by a receiving instrument in the general vicinity of the source without the need for any interconnecting wires.  He went on to develop two theories related to these observations, which are:

1. By using two grounded Tesla coil transmitter-receivers positioned at distant points on the Earth’s surface, it is possible to induce a flow of electrical current between them.
2. By incorporating a portion of the Earth as part of a powerful dual-elevated-terminal Tesla coil transmitter an electrical disturbance can be impressed upon the Earth and detected “at great distance, or even all over the surface of the globe.”

He also made the assumption that Earth is a charged body floating in space, possibly floating in an oppositely charged medium beyond the atmosphere.

A point of great importance would be first to know what is the capacity of the Earth? and what charge does it contain if electrified?  Though we have no positive evidence of a charged body existing in space without other oppositely electrified bodies being near, there is a fair probability that the Earth is such a body, for by whatever process it was separated from other bodies—and this is the accepted view of its origin—it must have retained a charge, as occurs in all processes of mechanical separation.

He was familiar with demonstrations that involved the charging of Leyden jar capacitors and isolated metal spheres with electrostatic influence machines (in modern terms, high-voltage (kV), low-current (µA) electrostatic generators).  By bringing these elements into proximity with each other, and also by making direct contact followed by their separation, the charge can be manipulated.  He had this in mind in the creation of his mental image, not being able to know that the model of Earth’s origin was inaccurate.  The accepted model of planetary origin is one of accretion and collision.

If it be a charged body insulated in space its capacity should be extremely small, less than one-thousandth of a farad.  But the upper strata of the air are conducting, and so, perhaps, is the medium in free space beyond the atmosphere, and these may contain an opposite charge.  Then the capacity might be incomparably greater.

Earth is a charged body, made so by processes—at least in part—related to the interaction between the continuous stream of charged particles called the solar wind that flows outward from the center of our solar system and Earth’s magnetosphere, and the upper atmospheric strata are conducting, or can be made so.  Earth's electrical self-capacitance is calculated to be about 708.5 microfarads, somewhat less than one thousandth of a farad.

In any case it is of the greatest importance to get an idea of what quantity of electricity the Earth contains.

Earth possesses a naturally existing negative charge with respect to the conducting region of the atmosphere beginning at an elevation of about 50 km.  The potential difference between the Earth and this region is on the order of 400,000 volts.  Near the Earth's surface there is a ubiquitous downward-directed E-field of about 100 V/m.

It is difficult to say whether we shall ever acquire this necessary knowledge, but there is hope that we may, and that is, by means of electrical resonance.  If ever we can ascertain at what period the Earth's charge, when disturbed, oscillates with respect to an oppositely electrified system or known circuit, we shall know a fact possibly of the greatest importance to the welfare of the human race.  I propose to seek for the period by means of an electrical oscillator, or a source of alternating electric currents.

The process is essentially the same as transmitting electricity by conduction through a wire.  The Earth itself is one of the conducting media involved in ground and air system technology.  Its large cross-sectional area provides a low resistance path for the flow of earth currents.  The greatest losses are apt to occur at the points where the transmitting-receiving plants and dedicated receiving stations are connected with the ground.

To close the circuit a second path is established between the two transmitter-receiver plants' elevated high-voltage terminals through the rarefied atmospheric strata above 5 miles (8.0 km) elevation.  The connection is made by some combination of capacitive coupling and electrical conduction through plasma.  While not an ohmic conductor, the density or pressure in this region of the troposphere and upwards is sufficiently reduced to so that, according to theory, the atmosphere’s insulating properties are easily impaired, allowing an electric current to flow.  Theory further states that the conducting region is developed through the process of atmospheric ionization in which the affected portions thereof are changed to plasma. 

The atmosphere below 5 miles (8.0 km) is also a propagating medium for a portion of the above-ground circuit.  Being an insulating medium, capacitive coupling is involved rather than true electrical conduction.  The practical construction limitation imposed upon the height of the elevated terminals can be overcome with a sufficiently high electrical potential.  With a highly energetic transmitter, as was intended at Wardenclyffe, the elevated terminal is charged to the point where the atmosphere around and above the facility becomes strongly ionized.  This leads to a flow of true conduction currents between the two terminals by a path up to and through the upper atmosphere, and back down to the other facility.  The ionization of the atmosphere directly above the elevated terminals is facilitated by the use of ionizing beams of ultraviolet radiation to form what might be called high-voltage plasma transmission lines. 

While a number of the wireless patents, including "Apparatus for transmitting electrical energy," U.S. Patent No. 1,119,732, December 1, 1914, describe a system which uses the plasma-conduction scheme, his "Art of transmitting electrical energy through the natural mediums," U.S. Patent No. 787,412, April 18, 1905 and some of the Wardenclyffe design notes from 1901 show the overall plan also involves electrostatically induced oscillations in the potential associated with Earth's self-capacitance.  According to theory, Earth itself behaves as an electrical resonator when it is excited at certain frequencies.  The operating frequencies at Wardenclyffe were from 1,000 Hz to 100 kHz.  The frequency range up to 30 kHz was found “to be most economical.”  Excitation of earth resonance at an harmonic of the 11.78 Hz fundamental frequency suggests energy transmission by means of a TM₀₀ spherical conductor “single-wire” surface wave transmission line mode.  This involves surface plasmon wave excitation.  The entire Earth can be electrically resonated with a single earth-resonance transmitter, so an earth-resonance based system would require, at a minimum, that only one World Wireless System transmitter be constructed.  Alternatively, two distantly spaced transmitter-receiver facilities could be constructed.  Such a system would not be so dependent upon the excitation of an earth-resonance mode. 

Tesla's concept of a global wireless electrical power transmission grid and telecommunications network based upon energy transmission by means of a spherical conductor transmission line with an upper three-space model return circuit, while perhaps not practical for power transmission, is feasible, defying no law of physics.  Global wireless transmission by means of a spherical conductor “single-wire” surface wave transmission line and a propagating TM₀₀ mode may also be possible, a feasibility study using a sufficiently powerful and properly tuned Tesla coil earth-resonance transmitter being called for.

In spite of ridicule, many of his ideas have been demonstrated to be essentially correct.  For example he correctly predicted the existence of the ionosphere and electrical resonance of the Earth-atmosphere system.  Resonance of the earth-ionosphere cavity with a fundamental frequency in the vicinity of 7.83 Hz was demonstrated in the 1950s as the Schumann resonance. The latter phenomenon was named after Schumann, for although Tesla had detected a resonance of the Earth-atmosphere system, he was not taken seriously in his time. Furthermore, he appears to have excited a different terrestrial resonance mode with a fundamental frequency of 11.78 Hz.

Misconceptions

World System functionality

It is believed by some that World Wireless System technology is intended only for wireless power transmission.  The prototype Wardenclyffe installation and the second facility planned in Scotland had a dual purpose.  Their primary function was multi-channel point-to-point trans-Atlantic wireless telecommunications and worldwide broadcasting.  The prototype system was also intended for proof-of-concept wireless power transmission demonstrations, although on a greatly reduced scale.

Propagation mode

Resonant inductive coupling

It is believed by some that energy transfer between a grounded resonance transformer electrical oscillator transmitter and a similarly designed grounded resonance transformer electrical energy receiver tuned to the same frequency is by resonant induction between tuned circuits. 

The inferiority of the induction method would appear immense as compared with the disturbed charge of ground and air method."

This was confirmed by a 2008 propagation study using the basic world system transmission-reception circuit, that achieved transmission range efficiencies greater than those achieved using the resonant electrical induction method.  The Leyh-Kennen demonstrations used short-range capacitive coupling, differing from the patented SYSTEM OF TRANSMISSION OF ELECTRICAL ENERGY that Tesla claimed would work by, "a propagation or flow of electrical energy, by conduction, through the earth and the air strata."  Capacitive coupling is mentioned in this patent, but not claimed.

Electromagnetic radiation

It was once thought the 200 kW Wardenclyffe prototype World Wireless station would have functioned by the production and propagation of electromagnetic radiation also known as the transverse electromagnetic (TEM) radio wave, but this is not the case.  The World Wireless System works by the creation of powerful disturbances in the Earth's natural electric charge and a spherical single conductor transmission line propagation mode.

I am not producing radiation in my system; I am suppressing electromagnetic waves.  But, on the other hand, my apparatus can be used effectively with electromagnetic waves.  The apparatus has nothing to do with this new method except that it is the only means to practice it.  So that in my system, you should free yourself of the idea that there is radiation, that energy is radiated.  It is not radiated; it is conserved.

Schumann Cavity resonance

It has been proposed World Wireless System technology involves energy transfer by means of a concentric spherical shell waveguide composed of Earth's surface and the ionosphere.  This earth-ionosphere cavity is known as the Schumann Cavity.  Natural lightning excites Schumann resonances that are observed at the lowest few resonance frequencies (about 8 Hertz and multiples of that).  Their measured Q's of order 5 to 10 suggest that the electrical disturbances produced by lightning make a few circuits of the Earth before damping out, and create a fairly definite terrestrial standing wave of a few cycles duration.

A consideration of the earth-ionosphere or concentric spherical shell waveguide propagation parameters as they are known today shows that wireless power transmission by direct excitation of a Schumann cavity resonance mode is not realizable.

The conceptual difficulty with this model is that, at the very low frequencies that Tesla said that he employed (1–50 kHz), earth-ionosphere waveguide excitation, now well understood, would seem to be impossible with either the Colorado Springs or the Long Island apparatus (at least with the apparatus that is visible in the photographs of these facilities)."

The maximum recommended operating frequencies of 25 kHz as specified by Tesla is far above the highest easily observable Schumann resonance mode (this is the 9th overtone) that exists at approximately 66.4 Hz. His selection of 25 kHz is wholly inconsistent with the operation of a system that is based upon the direct excitation of a Schumann resonance mode.

What is wanted for wireless transmission of power is for the electrical load connected to the receiver to draw power from the transmitter via the standing wave.  I.e., when the load is switched on, the transmitter should "feel" the load, as it would in a closed circuit, and respond by providing more power via the standing wave.

The current induced in the input impedance of the receiver should reciprocally induce power in the output impedance of the transmitter similar to the power that was transmitted initially.  This is a way of expressing the coupling between the transmitter and receiver required for the transmitter to "feel" the load on the receiver.  The Q is the value that produces an electric field in the cavity strong enough to induce the required current in the input impedance of the receiver.

At higher frequencies, the required Q is larger, but I expect that the Q of the Earth-ionosphere cavity probably decreases because propagation losses in the Earth and ionosphere increase.

Ionospheric conduction

It is believed by some the atmospheric path that would be used in the two-conductor method, i.e., the "second path," is the ionosphere, the uppermost strata of Earth's atmosphere starting at approximately 30 miles (48 km) in daytime and approximately 55 miles (89 km) at night.  The atmospheric strata through which energy can be transmitted has a barometric pressure of 75 mm, equivalent to an elevation of about 15 miles (24 km).  World Wireless System apparatus allows this elevation to be reduced down to approximately 5 miles (8.0 km) because of the exceedingly high potentials involved.

Related patents

• SYSTEM OF ELECTRIC LIGHTING, April 25, 1891, U.S. patent 454,622, June 23, 1891.
• MEANS FOR GENERATING ELECTRIC CURRENTS, August 2, 1893, U.S. patent 514,168, February 6, 1894.
• ELECTRICAL TRANSFORMER, March 20, 1897, U.S. patent 593,138, November 2, 1897.
• METHOD AND APPARATUS FOR CONTROLLING MECHANISM OF MOVING VESSEL OR VEHICLES, July 1, 1898, U.S. patent 613,809 November 8, 1898.
• SYSTEM OF TRANSMISSION OF ELECTRICAL ENERGY, September 2, 1897, U.S. patent 645,576, March 20, 1900.
• APPARATUS FOR TRANSMISSION OF ELECTRICAL ENERGY, September 2, 1897, U.S. patent 649,621, May 15, 1900.
• METHOD OF INTENSIFYING AND UTILIZING EFFECTS TRANSMITTED THROUGH NATURAL MEDIA, June 24, 1899, U.S. patent 685,953, November 5, 1901.
• METHOD OF UTILIZING EFFECTS TRANSMITTED THROUGH NATURAL MEDIA, August 1, 1899, U.S. patent 685,954, November 5, 1901.
• APPARATUS FOR UTILIZING EFFECTS TRANSMITTED FROM A DISTANCE TO A RECEIVING DEVICE THROUGH NATURAL MEDIA, June 24, 1899, U.S. patent 685,955, November 5, 1901.
• APPARATUS FOR UTILIZING EFFECTS TRANSMITTED THROUGH NATURAL MEDIA, March 21, 1900, U.S. patent 685,956, November 5, 1901.
• METHOD OF SIGNALING, July 16, 1900, U.S. patent 723,188, March 17, 1903.
• SYSTEM OF SIGNALING, July 16, 1900, U.S. patent 725,605, April 14, 1903.
• ART OF TRANSMITTING ELECTRICAL ENERGY THROUGH THE NATURAL MEDIUMS, May 16, 1900, U.S. patent 787,412, April 18, 1905.
• ART OF TRANSMITTING ELECTRICAL ENERGY THROUGH THE NATURAL MEDIUMS, April 17, 1906, Canadian Patent 142,352, August 13, 1912.
• APPARATUS FOR TRANSMITTING ELECTRICAL ENERGY, January 18, 1902, U.S. patent 1,119,732, December 1, 1914.

See also

• Wireless energy transmission
• Terrestrial stationary waves
• Surface plasmon
• Surface-wave-sustained mode
• Transmission medium
• Distributed generation
• Electricity distribution
• Electric power transmission

Apparatus

• Electric generator
• Isochronous electro-mechanical oscillator
• Tesla coil
• Magnifying Transmitter

Notes

1. ^ Massie, Walter W. & Charles R. Underhill, Wireless Telegraphy & Telephony, Van Nostrand, 1908; The Future of the Wireless Art,] pp. 67–71.
2. Margaret Cheney, Tesla: Man Out of Time, page 194
3. Anderson, Leland I., Nikola Tesla On His Work With Alternating Currents and Their Application to Wireless Telegraphy, Telephony and Transmission of Power, 21st Century Books, 2002, p. 170.

   In Colorado I erected a plant for the practical purpose of arriving at accurate data for the construction of a large plant. . . . I had already planned most of the details of the commercial plant, subsequently put up at Long Island, except that at that time the location was not settled upon.

4. "The Transmission of Electrical Energy Without Wires," Electrical World, March 5, 1904". 21st Century Books. 5 March 1904. Retrieved 4 June 2009.."
5. Ratzlaff, John T., Reference Articles for Solutions to Tesla's Secrets, Tesla Book Company, 1981; "The True Wireless", Electrical Experimenter, May 1919
6. "World System of Wireless Transmission of Energy," Telegraph and Telegraph Age, October 16, 1927
7. Anderson, Leland I., Nikola Tesla On His Work With Alternating Currents and Their Application to Wireless Telegraphy, Telephony and Transmission of Power, 21st Century Books, p. 128.

   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.

8. Seifer, Marc J., "Nikola Tesla and John Jacob Astor,", SIXTH INTERNATIONAL SYMPOSIUM NIKOLA TESLA 18–20 October 2006, Belgrade, SASA, Serbia
9. Maury Klein, The Power Makers: Steam, Electricity, and the Men Who Invented Modern America
10. Ratzlaff, John T., Tesla Said, Tesla Book Company, 1984; "The Disturbing Influence of Solar Radiation On the Wireless Transmission of Energy," Electrical Review and Western Electrician, July 6, 1912
11. ^ Ratzlaff, John T., Dr. Nikola Tesla  Complete Patents; System of Transmission of Electrical Energy, September 2, 1897, U.S. patent 645,576, March 20, 1900.
12. Martin, Thomas Commerford, "The Inventions, Researches and Writings of Nikola Tesla", The Electrical Engineer, New York, 1894; "Experiments With Alternating Currents of Very High Frequency, and Their Application to Methods of Artificial Illumination," AIEE, Columbia College, N.Y., May 20, 1891
13. Martin, Thomas Commerford, "The Inventions, Researches and Writings of Nikola Tesla", The Electrical Engineer, New York, 1894; “Experiments With Alternate Currents of High Potential and High Frequency," IEE Address, London, February 3, 1892.
14. ^ Martin, Thomas Commerford, "The Inventions, Researches and Writings of Nikola Tesla", The Electrical Engineer, New York, 1894; "On Light and Other High Frequency Phenomena," February 24, 1893, before the Franklin Institute, Philadelphia, March 1893, before the National Electric Light Association, St. Louis.
15. Electrical Experimenter, January 1919. pg. 615
16. Cheney, Margaret, Tesla: Man Out of Time, Prentice-Hall, Inc., 1981, p. 174.
17. Norrie, H. S., Induction Coils: How to make, use, and repair them. Norman H. Schneider, 1907, New York. 4th edition.
18. Martin, Thomas Commerford, "The Inventions, Researches and Writings of Nikola Tesla", The Electrical Engineer, New York, 1894; "Experiments With Alternating Currents of Very High Frequency, and Their Application to Methods of Artificial Illumination," AIEE, Columbia College, N.Y., May 20, 1891.

    "I suspend a sheet of metal a distance from the ceiling on insulating cords and connect it to one terminal of the induction coil, the other terminal being preferably connected to the ground.  Or else I suspend two sheets as illustrated in Fig. 29 / 125, each sheet being connected with one of the terminals of the coil, and their size being carefully determined.  An exhausted tube may then be carried in the hand anywhere between the sheets or placed anywhere, even a certain distance beyond them; it remains always luminous"

19. Definition of "Hertzian"
20. ^ Tesla, Nikola (2002). Nikola Tesla on His Work with Alternating Currents and Their Application to Wireless Telegraphy, Telephony, and Transmission of Power: An Extended Interview. 21st Century Books. pp. 96–97. ISBN 1893817016.
21. Carlson, W. Bernard (2013). Tesla: Inventor of the Electrical Age. Princeton University Press. ISBN 978-1-4008-4655-9.
22. Seifer, Marc J., Wizard: The Life and Times of Nikola Tesla. p. 228.
23. Tesla, Nikola, "The True Wireless". Electrical Experimenter, May 1919. (Available at pbs.org)
24. Ratzlaff, John T., Dr. Nikola Tesla  Complete Patents; System of Signaling, U.S. patent 725,605.
25. William Beaty, 'Energy-sucking' Radio Antennas, N. Tesla's Power Receiver.
26. William Beaty, "Tesla invented radio?". 1992.
27. Nikola Tesla's Contributions to Radio Developments tesla-symp06.org
28. A. H. Taylor, "Resonance in Aërial Systems". American Physical Society. Physical review. New York, N.Y.: Published for the American Physical Society by the American Institute of Physics. (cf. The Tesla coil in the receiver acts as a step-down transformer, and hence the current is greater than in the aerial itself.)
29. Ratzlaff, John T., Dr. Nikola Tesla  Complete Patents; Apparatus for Transmitting Electrical Energy], January 18, 1902, U.S. patent 1,119,732, December 1, 1914.
30. Seifer, Marc J., Wizard: The Life and Times of Nikola Tesla. p. 472. (cf. "Each tower could act as a sender or a receiver.  In a letter to Katherine Johnson, Tesla explains the need for well over thirty such towers".)
31. U.S. Patent 0685956
32. U.S. Patent 0685955 Apparatus for Utilizing Effects Transmitted From A Distance To A Receiving Device Through Natural Media
33. Nikola Tesla On His Work with Alternating Currents and Their Application to wireless Telegraphy, Telephony, and Transmission of Power, 21st Century Books, 2002, p. 170.
34. ART OF TRANSMITTING ELECTRICAL ENERGY THROUGH THE NATURAL MEDIUMS, May 16, 1900, U.S. patent 787,412, April 18, 1905.
35. ART OF TRANSMITTING ELECTRICAL ENERGY THROUGH THE NATURAL MEDIUMS, Apr. 17, 1906, Canadian Patent 142,352, Aug. 13, 1912.
36. "The Wonder World To Be Created By Electricity", Manufacturer's Record, September 9, 1915.
37. Electrical self-capacitance of Earth.
38. Feynman, Richard P., Robert B. Leighton, Matthew Sands, The Feynman Lectures on Physics Volume II. Mainly electromagnetism and matter, Chapters 4-12, Addison–Wesley, 1964.
39. Corum, Kenneth L., James F. Corum, Craig Spaniol, "Concerning Cavity Q", Proceedings of the 1988 International Tesla Symposium, International Tesla Society, 1988.
40. Massie, Walter W. & Charles R. Underhill, Wireless Telegraphy & Telephony, Van Nostrand, 1908; "The Future of the Wireless Art]"

    This mode of conveying electrical energy to a distance is not 'wireless' in the popular sense, but a transmission through a conductor, and one which is incomparably more perfect than any artificial one.  All impediments of conduction arise from confinement of the electric and magnetic fluxes to narrow channels.  The globe is free of such cramping and hinderment.  It is an ideal conductor because of its immensity, isolation in space, and geometrical form.  Its singleness is only an apparent limitation, for by impressing upon it numerous non-interfering vibrations, the flow of energy may be directed through any number of paths which, though bodily connected, are yet perfectly distinct and separate like ever so many cables.  Any apparatus, then, which can be operated through one or more wires, at distances obviously limited, can likewise be worked without artificial conductors, and with the same facility and precision, at distances without limit other than that imposed by the physical dimensions of the globe.

41. Anderson, Leland I., Nikola Tesla On His Work With Alternating Currents and Their Application to Wireless Telegraphy, Telephony and Transmission of Power, 21st Century Books, p. 203.

    You see the underground work is one of the most expensive parts of the tower.  In this system that I have invented it is necessary for the machine to get a grip of the Earth, otherwise it cannot shake the Earth.  It has to have a grip on the Earth so that the whole of this globe can quiver, and to do that it is necessary to carry out a very expensive construction.

42. Barnes, Arnold A., Jr., Robert O. Berthel, "A Survey of Laser Lightning Rod Techniques] AD-A239 988, August 12, 1991
43. Laser-Induced Plasma Channel
44. "Laser-Guided Energy"
45. "Vehicle Disabling Weapon"
46. "Laser Device May Provide U.S. Military Nonlethal Option"
47. Anderson, Leland I., Nikola Tesla On His Work With Alternating Currents and Their Application to Wireless Telegraphy, Telephony and Transmission of Power, 21st Century Books, 2002, p. 155.

    I operated according to the nature of the experiment, as I say, from very low frequencies up to 100,000, but most generally I operated with the frequencies which I explained in my patent, say up to 30,000, which I have found to be most economical.

48. Elmore, Glenn, "Introduction to the Propagating Wave on a Single Conductor," Corridor Systems Inc., 2009.
49. Marincic, Aleksandar, "Research of Nikola Tesla in Long Island Laboratory," International Scientific Conference in Honor of the 130th Anniversary of the Birth of Nikola Tesla, 1986.
50. Tesla's Big Mistake? William Beaty, September 1999
51. The Discovery of Schumann Resonance
52. Popovic, Vojin, "Nikola Tesla – True Founder of Radio Communications," Nikola Tesla Life Work of a Genius, Yugoslav Society for the Promotion of Scientific Knowledge "Nikola Tesla" Belgrade 1976.
53. Babylon Signal, August 1902.
54. 5 June 1899, NIKOLA TESLA COLORADO SPRINGS NOTES 1899–1900, Nolit, 1978
55. ^ Leyh, G. E. and M. D. Kennan, "Efficient Wireless Transmission of Power Using Resonators with Coupled Electric Fields," 2008 North American Power Symposium.

    The power flowed through the ambient electric fields and returned through Earth, similar to Tesla’s original concept from 1900.

56. "Wireless Power Transfer via Strongly Coupled Magnetic Resonances," André Kurs, Aristeidis Karalis, Robert Moffatt, J. D. Joannopoulos, Peter Fisher, and Marin Soljacic, Science 6 July 2007: 83-86. Published online 7 June 2007
57. SYSTEM OF TRANSMISSION OF ELECTRICAL ENERGY, 2 September 1897, U.S. Patent No. 645,576, 20 March 1900.

    “In some cases when small amounts of energy are required the high elevation of the terminals, and more particularly of the receiving-terminal D', may not be necessary, since, especially when the frequency of the currents is very high, a sufficient amount of energy may be collected at that terminal by electrostatic induction from the upper air strata, which are rendered conducting by the active terminal of the transmitter or through which the currents from the same are conveyed."

58. Corum, Kenneth L., James F. Corum, "Nikola Tesla and the Diameter of the Earth: A Discussion of One of the Many Modes of Operation of the Wardenclyffe Tower," 1996
59. Anderson, Leland I., Nikola Tesla On His Work with Alternating Currents and Their Application to wireless Telegraphy, Telephony, and Transmission of Power, 21st Century Books, 2002, p. 133.
60. ^ Henry Bradford in "Nikola Tesla On Wireless Energy Transmission," The Schumann Cavity Resonance Hypothesis
61. Corum, Kenneth L., James F. Corum, J. F. X. Daum, "Spherical Transmission Lines and Global Propagation, An Analysis of Tesla's Experimentally Determined Propagation Model" PV Scientific Instruments, 1996; p. 10.

Further reading

• Anderson, Leland, "Rare Notes from Tesla on Wardenclyffe" in Electric Spacecraft – A Journal of Interactive Research, Issue 26, September 14, 1998.  Contains drawings and selected typescripts of Tesla's notes from 1901, archived at the Nikola Tesla Museum in Belgrade.
• "Boundless Space: A Bus Bar"], The Electrical World, Vol 32, No. 19, November 5, 1898.
• Massie, Walter Wentworth, Wireless telegraphy and telephony popularly explained. New York, Van Nostrand. 1908.
• Tesla, Nikola, "The Transmission of Electrical Energy Without Wires", Electrical World and Engineer, March 5, 1904.
• Tesla, Nikola, "World System of Wireless Transmission of Energy"], Telegraph and Telegraph Age, October 16, 1927.

External links

• PBS Tesla Master of Lightning Tower of Dreams, global wireless telecommunications
• Wardenclyffe Tower at Structurae

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