Existing:
The World Wireless System was a turn of the 19th century proposed telecommunications and electrical power delivery system designed by inventor Nikola Tesla based on his theories of using Earth and its atmosphere as electrical conductors. Tesla claimed this system would allow for "the transmission of electric energy without wires" on a global scale[1] as well as point-to-point wireless telecommunications and broadcasting. He made public statements citing two related methods to accomplish this from the mid-1890s on. By the end of 1900 Tesla had convinced banker J. P. Morgan to finance construction of a wireless station (eventually sited at Wardenclyffe) based on his ideas intended to transmit messages across the Atlantic to England and to ships at sea. Almost as soon as the contract was signed Tesla decided to scale up the facility to include his ideas of terrestrial wireless power transmission to better compete with Guglielmo Marconi's radio based telegraph system.[2] Morgan refused to fund the changes and, when no additional investment capital became available, the project at Wardenclyffe was abandoned in 1906, never to become operational.
During this period Tesla filed numerous patents associated with the basic functions of his system, including transformer design, transmission methods, tuning circuits, and methods of signaling. He also described a plan to have some thirty Wardenclyffe-style telecommunications stations positioned around the world to be tied into existing telephone and telegraph systems. Tesla would continue to elaborate to the press and in his writings for the next few decades on the system's capability's and how it was superior to radio-based systems.
Despite Tesla's claims that he had "carried on practical experiments in wireless transmission"[3] there is no documentation he ever transmitted power beyond relatively short distances, and modern scientific opinion is generally that his wireless power scheme would not have worked.
Proposed: World Wireless was a turn of the 19th century telecommunications and electrical power system design proposal made by inventor Nikola Tesla and based on his theories of using Earth and its atmosphere as electrical conductors. Tesla claimed this system would allow for "the transmission of electric energy without wires on a global scale[1] for point-to-point wireless telecommunications, broadcasting and industrial power transfer. From the mid-1890s on he made public statements about methods to accomplish this. By the end of 1900 Tesla had convinced banker J. P. Morgan to provide $150,000 to finance construction of a wireless system to transmit messages across the Atlantic between the United States and England, and to ships at sea, based on his ideas. After the contract was signed Tesla decided to construct a single more powerful station, instead of two smaller stations as had originally been discussed, in order to extend its range and better compete with Guglielmo Marconi's radio-wave based wireless system.[2][3] Costs tripled due to an economic upheaval and construction came to a halt. Morgan refused to provide further funding, and when no additional investment capital became available from other investors the Wardenclyffe station was abandoned in 1906, never to become fully operational.
During this period Tesla was granted numerous patents associated with the basic functions of his system, including transformer design, transmission methods, tuning circuits, and methods of signaling. He also described a plan to have some thirty World Wirelsss system telecommunications stations, based upon the Wardenclyffe power plant and Wardenclyffe tower prototypes, positioned around the world, to be tied into existing telephone and telegraph systems. Tesla would continue to elaborate to the press and in his writings for the next few decades on the system's capability's and how it would prove to be superior to systems based upon radio waves.
Tesla claimed that he had carried on practical experiments in wireless energy transmission, and while there is no clear documentation that he ever transferred power beyond relatively short distances, there is modern scientific opinion that his wireless telecommunications scheme could have worked.
^Wheeler, L. P. (August 1943). "Tesla's contribution to high frequency". Electrical Engineering. 62 (8). IEEE: 355–357. doi:10.1109/EE.1943.6435874. ISSN0095-9197.
^Uth, Robert (2000). "Dennis Papadopoulos interview". Tesla: Master of Lightning - companion site for 2000 PBS television documentary. PBS.org, US Public Broadcasting Service website. Retrieved November 19, 2014.
I would beg you in all earnestness to peruse the following statement of facts which I have brought separately to your attention.
1. Five years ago (as you may have gathered from my original announcement in the Century of June 1900, copy of a patent specification filed May 15, 1900, and article in the Electrical World and Engineer of March 5, 1900) I succeeded in encircling the Earth with electrical waves. What gave to this result far-reaching in itself, a tremendous significance, was the observation that in their passage from Colorado Springs to the diametrically opposite region of the globe and return, the waves suffered no perceptible diminution of intensity, thus affording an absolute experimental evidence, that by my system power in unlimited amounts can be transmitted, without wire, to any distance and, virtually, without loss.
2. I recorded my discoveries in the patent office and secured broad and uncontested rights in Patents, some of which I am still keeping back, for reasons which it is unnecessary to explain. When they appear they will create a profound impression.
3. I was even then firmly convinced that these advances would prove of greater importance than the steam engine, the telegraph, the telephone, and my multiphase motor combined, for the offered an ideal solution of the problems of fuel, transportation, and intelligence-transmission in all their ramifications.
4. Desiring to obtain a support such as this work was deserving, more for the good of the world then my own, I approached you, naturally enough with the easily realizable project of establishing communication across the Atlantic, which required a smaller investment.
5. I was fortunate to enlist your interest, but not quite on the lines of my own suggestion. I contemplated the formation of one or two companies to which all inventions in wireless telegraphy and telephony and my system of lighting were, respectively, to be assigned and proposed that you take fifty-one percent of the stock (not fifty, as you yourself said in our first conversation, because then you would not control), the remainder to go to my parent company. But when I received your formal letter it specified an interest of fifty-one percent in patents on these inventions. That was different though my share was the same. It was a simple sale. The terms were entirely immaterial to me and I said nothing for fear of offending you. You have repeatedly referred to some stock and it is just possible, that a mistake was made, and that you intended to take exactly what I had proposed, and what would have been, for many reasons, greatly to my advantage.
6. Your participation called for a careful revision of my plans. I could not develop the business slowly in grocery shop fashion. I could not report yacht races or signal incoming steamers. There was no money in this. This was no business for a man of your position and importance. Perhaps you have never fully appreciated the sense of this obligation.
7. When I discovered, rather accidentally, that others, who openly cast ridicule on what I had undertaken and discredited my apparatus were secretly employing it, evidently bent on the same task, I found myself confronted with wholly unforeseen conditions. How to meet them was a question. Of course I could not enjoin the infringers. In Canada, almost midway, I had no rights. My Patents on the art of individualization, insuring non-interference and non-interferability, were not as yet granted in England and the United States. Suppose I was anticipated in this invention? Then I would have to rely on ordinary tuning. This was in a measure, satisfactory so long as I was alone, but shrewd competitors, with the advantage they had, could make me fall short, as the capital I had at disposal was only a sufficient for two small plants. Once I failed with you in the first attempt, you would not listen to any other proposition. Once I lost your support I could not because of your personality and character of our agreement, interest anybody else, at least not for several years, until, the business would be developed and the commercial value of my patents recognized. But there was one way, the only way, of meeting every possible emergency, and making the ultimate success perfectly certain.
8. Here I must add a purely explanatory paragraph. Suppose a plant is constructed capable of sending signals within a given radius, and consider an extension to twice this distance. The area being then four times as large the returns will be, roughly, fourfold on account of this alone. The messages, however, will become more valuable. Approximately computed, the average price will be tripled. This means that a plant with a radius of activity twice as large will earn twelve times as much. But it will cost scarcely twice as much. Hence in investing a certain sum destined for two small plants into a single one, the earnings will be six-fold increased. The greater the distance the greater the gain until, when the plant can transmit signals to the uttermost confines of the Earth, its earning power becomes, so to speak, unlimited.
9. Thereby to do was to construct such a plant. It would yield the greatest returns, not only for the reasons just mentioned, but also because every other plant erected anywhere in the world, by anyone, was sure to be turned into a source of income. It would give the greatest force to my patents and insure a monopoly. It would make certain the acceptance of my system by all governments. It discounted in advance all possible drawbacks, as anticipation of the results by the trespassers of my rights and delay. It offered possibilities for a business on a large, dignified scale, commensurate with your position in life and of mine as a pioneer in this art, who has originated all its essential principles.
10. The practicability of such an undertaking I had already demonstrated in Colorado, but to make those feeble effects, barely detectable by delicate instruments, commercially available all over the earth, required a very large sum of money. You had told me from the outset that I should not ask for more, but the work was of such transcending importance and it was of such enormous value in your hands, that I undertook to explain to you the state of things on your first returned from abroad. You seem to misunderstand me. That was most unfortunate. Had I obtained your hearing, your enemies would not have succeeded in inflicting you injuries, for the first motor or lamp operated across the Pacific would have delivered them in your power. To achieve a great results is one thing, to achieve it at the right moment is another. That favorable moment is gone forever. Your popularity has suffered, the moral force of my work has been weakened by delay, the audacious schemers who have dared to fool the crowned heads of Europe, the President of the United States, and even His Holiness the Pope, have discredited the art by incompetent attempts and spoiled the public by false promises which it cannot distinguish from those sure of fulfillment, based on knowledge and skill and legitimate right. That is what pains me most.
11. Still, in spite of all this, Mr. Morgan, I can realize what I have held out to you when you yourself said to me that “you have no doubt”. I know you must be skeptical about getting hundredfold returns, but if you will help me to the end you will soon see that my judgment is true. When my first plant is completed I can place a dozen of such at once. I do not need to wait for returns from subscribers. There are one thousand million dollars invested in a submarine cables alone. This immense property is threatened with destruction because just as soon as people find that messages for, say, five cents a word can be transmitted to any distance, nothing will stop the demand for the cheaper and quicker means of communication. The investment in cables is too large to pay on this low basis and the only chance the companies have is to take hold of the new advances. My patents control every essential element of the art. They are impregnable. In your hands, and backed by these great results, they should be of enormous value.
12. My work is now far advanced and could be finished quickly. I have expended about $250,000 in all and a much smaller sum of separates me from a great triumph. If you have lost faith in me have you not someone in whose knowledge and ability you have greater confidence than in mine, and to whom I could explain? Seventy-five thousand dollars would certainly complete the plant and then I would have no difficulty whatever in getting all the capital necessary for the further commercial expansion.
13. Since a year, Mr. Morgan, there has been hardly a night when my pillow was not bathed in tears, but you must not think be a weak man for that. I am perfectly sure to finish my task, come what may. I am only sorry that after mastering all the difficulties which seemed insuperable, and acquiring a special knowledge and ability which I now alone possess, and which, if applied effectively, would advance the world a century, I must see my work delayed.
In hope of hearing from you favorably, I remain,
Your is most faithfully,
N. Tesla
[Tesla, Nikola, 1856-1943. http://lccn.loc.gov/mm82050302, Library of Congress, Nikola Tesla correspondence, 1890-1934. 7 microfilm reels.]
Counsel
What would an engineer have to do to the wireless systems of today in order to produce very little radiation of electromagnetic waves and produce a large amount of these earth currents? What changes would he have to make in the system?
Tesla
He would have to construct and operate the apparatus described in my patents and in my lectures.
Counsel
He would have to get very much more inductance in the system than he has today, relatively?
Tesla
It is just like this: In an enterprise of this kind, you have to start with certain fundamental propositions. If you are to build a commercial plant, the question comes up how much money is it to cost. Now, you go to specify before your capitalists the various parts of the plant, and you will find that your machinery and the aerial structure will cost so much. If your capitalists are willing to go deep into their pockets, you can put up a tremendous antenna because, as you know, as I pointed out in 1893, that the effects will be proportionate to the capital invested in that part; but you will find great limits there.
I designed a plant [(Wardenclyffe)] years ago with a large capacity and put it before certain architects. They figured that the antenna would cost $450,000 and I had to modify my plans. As you see, you are limited by cost as to the size of the antenna; that is, you are limited as to the capacity and, furthermore, you have selected the frequency. In order to lower the frequency so that there would be no wasteful radiation of energy, you have to employ a large inductance. You have to employ a capacity as large as permissible, and you must use a large inductance in order that you may reach the low frequency which is economical.
Counsel
What low frequency is it that is economical?
Tesla
In a patent which appeared in April 1905, the application of which was filed on May 15, 1900, I have enunciated the law of propagation, which I have explained, and have stated that the frequencies should not be more than 30,000 or 35,000 cycles at most, in order to operate economically. [Cooper, Drury W., internal document of the law firm Kerr, Page & Cooper, New York City, 1916. (In Nikola Tesla On His Work With Alternating Currents and Their Application to Wireless Telegraphy, Telephony, and Transmission of Power, Leland I. Anderson, editor, Sun Publishing Company, 1992, pp. 143-144.)]
Tesla demonstrated wireless power transmission at Colorado Springs, lighting incandescent electric lamps positioned relatively close to the structure housing his large experimental magnifying transmitter (recorded in the "The Problem of Increasing Human Energy" article published in Century Magazine, June 1900 and claimed afterwards that he had, "carried on practical experiments in wireless transmission." [Electrocraft - Volume 6 - 1910, Page 389]). He believed that he had achieved Earth electrical resonance at Colorado Springs that, according to his theory, would produce electrical effects at any terrestrial distance. [W. Bernard Carlson, Tesla: Inventor of the Electrical Age, Princeton University Press - 2013, page 301.]
[These are generic terms that refer] It is a generic term that refers to a number of different power transmission technologies that use time-varying [electric, magnetic, or] electromagnetic fields. ["Gopinath"] ["Sazonov"] ["Wilson"]
Wireless transmission is useful to power electrical devices in cases where interconnecting wires are inconvenient, hazardous, or are not possible.
In wireless power transfer, a transmitter device connected to a power source, such as the mains power line, transmits [electrical energy] power by electromagnetic fields across an intervening space to one or more receiver devices, where it is converted back to electric power and utilized. ["Shinohara1"]
The action of a conventional electrical transformer is the simplest form of wireless power transmission by non-resonant magnetic induction. The primary and secondary circuits of a transformer are not electrically connected. Energy transfer takes place through a process known as mutual induction. Principal functions are stepping the primary voltage either up or down and electrical isolation. The high-voltage electrical power distribution transformer, the stove-top induction cooker, the electric toothbrushbattery charger and Car Wheel are examples of how this principle is used.
The main drawback to this basic form of wireless transmission is its short range. Even over a relatively small distance the non-resonant inductive coupling method is grossly inefficient, wasting much of the transmitted energy. The receiving coil or electrodes must be directly adjacent to the transmitting induction coil of electrodes in order to be strongly coupled.
The application of electrical resonance improves the situation. When resonant coupling is used the transmitter and receiver are mutually tuned together to the same frequency. Also, the drive current can be modified from a sinusoidal to a nonsinusoidal transient waveform.
Pulse power transfer occurs over multiple cycles. In this way significant power may be transmitted over a distance of up to a few times the size of the primary coil. Transmitting and receiving coils are usually single layer solenoids or flat spirals with series capacitors, which, in combination, allow the receiving element to be tuned to the transmitter frequency.
This approach is suitable for universal wireless charging pads for portable electronics such as mobile phones. It has been adopted as part of the Qi wireless charging standard.
ref name=Car_Wheel
A means of powering electric vehicles using radio frequency transmission has been demonstrated at CEATEC 2014 Via-wheel power transfer to vehicles in motion
T. Ohira
DOI: 10.1109/WPT.2013.6556928 Conference: Wireless Power Transfer (WPT), 2013 IEEE
ABSTRACT
This paper proposes a non-magnetic non-resonant wireless power transfer scheme to vehicles during in motion, which is called via-wheel power transfer or V-WPT. We focus on the steel belt usually built in a tire for vehicles. It can collect RF displacement current if another electrode is buried beneath the road by analogy to an overhead wire for railways or trolleys. Since the tire always surely touches the road surface, it could be an ultimate wireless power transfer scheme. Being free from air gap (zero-gap coupling) unlike the twin coils, high dielectric constant of the tire permits high efficiency displacement current with much less electromagnetic field leakage to outside than trans-air-gap approaches. V-WPT can power the vehicles even while running, extend the cruising range without regard to battery limitations, and be the finest solution for future green mobility.
http://www.researchgate.net/publication/261203154_Via-wheel_power_transfer_to_vehicles_in_motion
In atmospheric plasma channel coupling, energy is transferred between two electrodes by electrical conduction through ionized air.[9] When an electric field gradient exists between the two electrodes, exceeding 34 kilovolts per centimeter at sea level atmospheric pressure, an electric arc occurs.[10] This atmospheric dielectric breakdown results in the flow of electric current along a random trajectory through an ionized plasma channel between the two electrodes. An example of this is natural lightning, where one electrode is a virtual point in a cloud and the other is a point on Earth. Laser Induced Plasma Channel (LIPC) research is presently underway using ultrafast lasers to artificially promote development of the plasma channel through the air, directing the electric arc, and guiding the current across a specific path in a controllable manner.[11] The laser energy reduces the atmospheric dielectric breakdown voltage and the air is made less insulating by superheating, which lowers the density () of the filament of air.[12]
This new process is being explored for use as a laser lightning rod and as a means to trigger lightning bolts from clouds for natural lightning channel studies,[13] for artificial atmospheric propagation studies, as a substitute for conventional radio antennas,[14] for applications associated with electric welding and machining,[15][16] for diverting power from high-voltage capacitor discharges, for directed-energy weapon applications[17][18][19][20] and electronic jamming.[21]
^Brown, William C. (1984). "The history of power transmission by radio waves". MTT-Trans. on Microwave Theory and Technique. 32 (9). Inst. of Electrical and Electronic Engineers: 1230–1234. Retrieved November 20, 2014.
Referring to the different instrumentalities described as being used by you for supplying sustained electrical oscillations to an antenna of high capacity and tuned to the frequency of the current impressed, for the transmission of energy without wires, what, if any, difference in principle was involved in the transmitting of such energy to a distant telephone, for instance, or for signaling, as compared with such transmission to any other form of translating device, such for instance, as a lamp?
Tesla
There is no difference whatever that I can see in the principle.
Counsel
Was there any difference in the equipment employed for these two purposes?
Tesla
Absolutely none that I can see. [Cooper, Drury W., internal document of the law firm Kerr, Page & Cooper, New York City, 1916. (In Nikola Tesla On His Work With Alternating Currents and Their Application to Wireless Telegraphy, Telephony, and Transmission of Power, Leland I. Anderson, editor, Sun Publishing Company, 1992, p. 145.)]
When I spoke of these enormous potentials, I was describing an industrial plant on a large scale because that was the most important application of these principles, but I have also pointed out in my patents that the same principles can be applied to telegraphy and other purposes.That is simply a question of how much power you want to transmit. [Cooper, Drury W., internal document of the law firm Kerr, Page & Cooper, New York City, 1916. (In Nikola Tesla On His Work With Alternating Currents and Their Application to Wireless Telegraphy, Telephony, and Transmission of Power, Leland I. Anderson, editor, Sun Publishing Company, 1992, p. 171-172.)]
There is no documented evidence Tesla ever transmitted significant power beyond those short-range demonstrations adjacent to the transmitter, perhaps 300 feet (91 m) [citation needed]. The writer Marc Seifer noted opinion amongst Tesla proponents that ranged from the idea not being practicable to claims some of Tesla's observations were valid. [Marc Seifer, Wizard: The Life and Times of Nikola Tesla - page 471-472.] Other investigators note that Tesla seemed over estimated the conductivity of the Earth and the atmosphere and vastly underestimated the drop in loss of power over distance.
There is also little evidence that Tesla achieved wireless communication over significant distances. The only report of long distance communication by Tesla, from a legal statement he made in 1916, is that in 1899 he transmitted a signals over a distance of about 10 miles (16 km) (Legal statement by Tesla to attorney Drury W. Cooper, from 1916 internal document of the law firm Kerr, Page & Cooper, New York City, cited in Anderson, 1992).
In 1990, Tesla biographer Marc Seifer gathered statements from Dr. Alexandar Marinčić, former director of the Nikola Tesla Museum, Belgrade, engineer historian Leland I. Anderson, large Tesla coil builder Robert Golka, mathematician Eric Dollard, and electrical engineer Dr. James F. Corum, Ph.D., about the viability of the Tesla wireless system.
Dr. Marinčić, Mr. Anderson, and Mr. Golka expressed the opinion that global transmission of electrical energy at industrial power levels would not be "practicable".
Both Mr. Dollard and Dr. Corum concluded that the Tesla wireless system apparatus is "viable". Dr. Corum further asserted that Tesla's claim to have measured a terrestrial pulse that rebounded off the antipode of the earth is "valid" and that his calculated earth resonance frequency is essentially correct. [Marc Seifer, Wizard: The Life and Times of Nikola Tesla, pp. 471-472.]
"Today, Tesla’s exact plan for the site remains a mystery even as scientists agree on the impracticality of his overall vision. The tower could have succeeded in broadcasting information, but not power." [Broad, William J. (May 4, 2009). "A Battle to Preserve a Visionary’s Bold Failure". New York Times (New York: The New York Times Co.). pp. D1.]
im·prac'ti·cal'i·ty (-kal'i-te), im·prac'ti·cal·ness n.
im·prac·ti·cal
(im-prak'ti-kəl) adj.
1. Unwise to implement or maintain in practice: Refloating the sunken ship proved impractical because of the great expense.
2. Incapable of dealing efficiently with practical matters, especially finances.
3. Not a part of experience, fact, or practice; theoretical.
4. Impracticable. See Usage Note at impracticable.
im·prac·ti·ca·ble
(im-prak'ti-kə-bəl) adj.
1. Impossible to do or carry out: Refloating the sunken ship intact proved impracticable because of its fragility.
2. Unfit for passage: roads impracticable in winter.
3. Archaic Unmanageable; intractable.
Usage Note: The adjective impracticable applies to a course of action that is impossible to carry out or put into practice; impractical, though it can be used in this way, also can be weaker in sense, suggesting that the course of action would yield an insufficient return or would have little practical value. A plan for a new stadium may be rejected as impracticable if the site is too marshy to permit safe construction, but if the objection is that the site is too remote for patrons to attend games easily, the plan is better described as impractical. See Usage Note at practicable.
Referring to the different instrumentalities described as being used by you for supplying sustained electrical oscillations to an antenna of high capacity and tuned to the frequency of the current impressed, for the transmission of energy without wires, what, if any, difference in principle was involved in the transmitting of such energy to a distant telephone, for instance, or for signaling, as compared with such transmission to any other form of translating device, such for instance, as a lamp?
Tesla
There is no difference whatever that I can see in the principle.
Counsel
Was there any difference in the equipment employed for these two purposes?
Tesla
Absolutely none that I can see. [Cooper, Drury W., internal document of the law firm Kerr, Page & Cooper, New York City, 1916. (In Nikola Tesla On His Work With Alternating Currents and Their Application to Wireless Telegraphy, Telephony, and Transmission of Power, Leland I. Anderson, editor, Sun Publishing Company, 1992, p. 145.)]
When I spoke of these enormous potentials, I was describing an industrial plant on a large scale because that was the most important application of these principles, but I have also pointed out in my patents that the same principles can be applied to telegraphy and other purposes.That is simply a question of how much power you want to transmit. [Cooper, Drury W., internal document of the law firm Kerr, Page & Cooper, New York City, 1916. (In Nikola Tesla On His Work With Alternating Currents and Their Application to Wireless Telegraphy, Telephony, and Transmission of Power, Leland I. Anderson, editor, Sun Publishing Company, 1992, p. 171-172.)]
It has been suggested that Tesla underestimated the drop in loss of power over distance, that is to say, the attenuation of the transmitted electric field energy as a function of distance ( e-ad ).
The propagation of radio waves along the surface of the ground has been discussed from a theoretical standpoint for many years. As long ago as 1907, Zenneck [1] showed that a wave, which was a solution of Maxwell's equations, traveled without change of pattern over a flat surface bounding two homogeneous media of different conductivity and dielectric constants. When the upper medium is air and the lower medium is a homogeneous dissipative ground, the wave is characterized by a phase velocity greater than that of light and a small attenuation in the direction along the interface. Furthermore, this Zenneck surface wave, as it has been called, is highly attenuated with height above the surface. In 1909 Sommerfeld [2] solved the problem of a vertical dipole over a homogeneous ground (half-space). In an attempt to explain the physical nature of his solution, he divided the expression for the field into a "space wave" and a "surface wave." Both parts, according to Sommerfeld, are necessary in order to satisfy Maxwell's equations and the appropriate boundary conditions. The surface-wave part varied inversely as the square root of the range, and it was identified as the radial counterpart of the plane Zenneck surface wave.
[1] J. Zenneck, "Über die Fortpflanzung ebener elektromagnetischer Wellen längs einer ebenen Leiterfläche und ihre Beziehung zur drahtlosen Telegraphie," Ann. Physik [4] 23, 846 (1907). [2] A. Sommerfeld, "Uber die Ausbreitung der Wellen in der Drahtlosen Telegraphie" (The Propagation of Waves in Wireless Telegraphy), Ann. Physik [4] 28, 665 (1909); 62, 95 (1920); 81, 1135 (1926).
[Wait, James R., "Excitation of Surface Waves on Conducting, Stratified, Dielectric-Clad, and Corrugated Surfaces," Journal of Research of the National Bureau of Standards Vol. 59, No.6, December 1957.]
[Tesla's] proposed system was . . . inefficient. . . .
[Wheeler, L. P. (August 1943). "Tesla's contribution to high frequency". Electrical Engineering (IEEE) 62 (8): 355–357. doi:10.1109/EE.1943.6435874. ISSN 0095-9197.]
"Because the dimensions of the earth ionospheric wave guide, are so enormous, you can transmit power, but not very much power. . . . There are two ways of propagating [electric current without wires], . . . between the earth and the ionosphere [or] you forget the ionosphere, and the current is carried only by the earth. . . . The problem with both modes in terms of really sending a lot of energy is they attenuate a lot. When you have current, if the earth and the ionosphere were superconductors, wonderful, we'd be able to do it. But they are poor conductors. So what happens is a lot of energy goes into heating the ground or heating the ionosphere."
"Tesla's idea of propagation is perfectly valid."
["Dennis Papadopoulos interview". Tesla: Master of Lightning - companion site for 2000 PBS television documentary. PBS.org, US Public Broadcasting Service website. 2000.]
Wave transfer of information functions well with tiny energy levels of even micro-watts. But a typical light bulb of 100 Watts needs 100 million times greater energy transfer. This is physically possible, but there are side effects when that much energy is going in all directions. Broad area distributed, wireless electromagnetic power at levels used by a modern home will not happen. Furthermore, because of inefficiencies of traveling wave production and conversion, and our collective need for the world to be more efficient, not less, wireless power is a very local solution to specialized specific problems and will not replace wiring.
[Chathan Cooke, Principal Research Engineer, MIT Laboratory for Electromagnetic and Electrical Systems. (In Edison's Concrete Piano: Flying Tanks, Six-Nippled Sheep, Walk-On-Water Shoes, and 12 Other Flops From Great Inventors by Jean Wearing, ECW Press, 2009, p. 98.]
Some say Tesla over estimated the conductivity of the earth. And, it is said, he over estimated the conductivity of the atmosphere as well.
Tesla not only thought that the globe was a good conductor but that the moderate altitude atmospheric layers were excellent conductors. [Curty, Jari-Pascal; Declercq, Michel; Dehollain, Catherine; Joehl, Norbert (2006). Design and Optimization of Passive UHF RFID Systems. Springer. p. 4. ISBN0387447105.]
[Tesla was] wrong about a lot of things. His vision for wireless transmitters went well beyond modern applications. He envisioned his wireless transfer of energy would not only power households but "aerial machines . . . propelled around the earth without a stop and the sun's energy controlled to create lakes and rivers for motive purposes and transfonnation of arid deserts into fertile land. . . . [Wearing, Judy (2009). Edison's Concrete Piano: Flying Tanks, Six-Nippled Sheep, Walk-On-Water Shoes, and 12 Other Flops From Great Inventors. ECW Press. p. 98. ISBN1554905516.] [unreliable source?]
[Tesla's] error was in not realizing that both the ionosphere and earth were poor conductors, and that most of the transmitted energy would be burned up in heat losses. In addition, the transmitted power would radiate in every direction, causing still further losses. . . . both ways are very inefficient for transferring energy due to the mediums' low level of conductivity. [Wagner, John, Innovation: The Lessons of Nikola Tesla, Blue Eagle Group, 2008, p. 78.] [unreliable source?]
[Tesla] failed because of diffusion of the wireless power, which depends on the frequency of operation and the size of the transmitting antenna. He used an operating frequency of 150 kHz. [Tomar, Anuradha; Gupta, Sunil (July 2012). "Wireless power Transmission: Applications and Components". International Journal of Engineering Research & Technology 1 (5). ISSN 2278-0181.] [unreliable source?]
[Tesla] failed because the transmitted power was diffused in all directions using 150 kHz radiowaves. [Shinohara, Naoki (2014). Wireless Power Transfer via Radiowaves. John Wiley & Sons. p. 11. ISBN1118862961.] [unreliable source?]
The reason that it [the Tesla wireless system] won't work is because it is based on the original theory of radio transmission for communication purposes. Here, only a minute voltage is sufficient to convey information to the receiver. The most powerful radio transmitters ever built could generate intense fields in the proximity of the station. Yet within a few miles they were merely radio signals, albeit stronger than some. It is all governed by the immmutable laws of electromagnetic radiation. This law says that the strength of the field is inversely proportional to the square of the distance. [Coe, Lewis (2006). Wireless Radio: A History. McFarland. p. 112. ISBN0786426624.] [unreliable source?]
[Lewis,] 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. [Cooper, Drury W., internal document of the law firm Kerr, Page & Cooper, New York City, 1916. (In Nikola Tesla On His Work With Alternating Currents and Their Application to Wireless Telegraphy, Telephony, and Transmission of Power, Leland I. Anderson, editor, Sun Publishing Company, 1992, p. 133.)]
"By zapping the air with a pair of powerful laser bursts, researchers at the University of Arizona have created highly focused pathways that can channel electricity through the atmosphere. The new technique can potentially direct an electrical discharge up to 10 meters (33 feet) away or more, shattering previous distance records for transmitting electricity through air. . . ."
"The current breakthrough was achieved by sending a femtosecond laser light pulse as the "igniter" and a nanosecond pulse as a "heater" along the same path, and by understanding how the atmosphere behaves when it was subjected to these extremely energetic light pulses. The researchers recognized that it wasn't the actual plasma created by the lasers that made the atmosphere more conductive; it was the subsequent superheating that lowered the density of the filament of air. Without some additional input of energy, however, this zone of lower density quickly collapsed. To improve both distance and duration, a second energy source was needed to rapidly reheat the air, stabilizing the filament just long enough to carry an electrical current."
"Laser-assisted guiding of electric discharges around objects"
Clerici, Matteo, Yi Hu, Philippe Lassonde, Carles Milián, Arnaud Couairon, Demetrios N. Christodoulides, Zhigang Chen, Luca Razzari, François Vidal, François Légaré, Daniele Faccio, Roberto Morandotti
American Association for the Advancement of Science, 2015.
"Electric breakdown in air occurs for electric fields exceeding 34 kV/cm and results in a large current surge that propagates along unpredictable trajectories. Guiding such currents across specific paths in a controllable manner could allow protection against lightning strikes and high-voltage capacitor discharges. Such capabilities can be used for delivering charge to specific targets, for electronic jamming, or for applications associated with electric welding and machining. We show that judiciously shaped laser radiation can be effectively used to manipulate the discharge along a complex path and to produce electric discharges that unfold along a predefined trajectory. Remarkably, such laser-induced arcing can even circumvent an object that completely occludes the line of sight."
The concept of using a laser: to create an ionized path in the atmosphere to act as a lightning rod is not new. Over the past four decades since the invention of the laser, there have been many documented investigations into the ionization of atmospheric gasses with an eye towards creating a laser lightning rod (LLR). Initial experimental attempts using lasers operating in the IR were not successful. Although some ionization was attained, it was found that the laser beam was self-quenching so that distances of only tens of meters were obtained in the atmosphere near sea level.
"Laser Type Ultra-violet Radiation Feasibility for Lightning and Atmospheric Propagation Studies"
J. R. Stahmann
Lightning and Transients Research Inst., St. Paul, MN, Oct. 1964
The feasibility of a laser type ultra-violet source as a possible substitute for the continuously supported wire antenna, used for artificial atmospheric propagation studies and to trigger lightning for natural lightning channel studies, is considered. The energy required to produce an electron plasma or even a molecular plasma is quite high. A powerful laser beam would provide an intense concentration of energy. However, it is difficult if not impossible to produce lasers with wavelengths below the 1000 A required to ionize air molecules. Laboratory experiments were limited to the use cf a 14 kilowatt carbon arc as a source in the far ultra-violet. No long spark diversion similar to that found with a jet plasma (10 to 108 ions/cc) was observed with the carbon arc source. Methods of selective ionization to distribute the ions over the beam with just the density required for the conductivity of a jet plasma include possible rocket distribution of combustible particles to be ignited by a conventional laser beam for distances of several miles to produce islands of plasma which possibly could allow a discharge to propagate.
LIPC weapon combines lasers and lightning, proves soldiers are a bunch of nerds
The problem with laser weapons is this -- they need a lot, a lot of power. Seriously. Some of those big, plane-mounted prototypes choke down enough juice to power a whole city. Not so with the Laser-Induced Plasma Channel weapon being developed by researchers at Picatinny Arsenal. While still using plenty of electricity, this more moderately specced laser is just powerful enough to strip electrons off the air molecules around it generating a thin filament of plasma. Its not the high-intensity laser pulse that does the damage, though. Instead, the channel of plasma is used as a conduit for a high-voltage blast of electricity. That laser-assisted bolt of lightning could disable vehicles, people and even IEDs. There are plenty of obstacles, including making the weapon rugged enough for battlefield use and reliable enough to keep the plasma channel from leading the blast of electricity back into the laser and damaging it. Now, if only we could find the video that still above was taken from.
Thought that title might get your attention, but shooting lightning bolts down laser beams is just what a device being developed at the Picatinny Arsenal military research facility in New Jersey is designed to do. Known as a Laser-Induced Plasma Channel, or LIPC, the device would fry targets that conduct electricity better that the air or ground that surrounds them by steering lightning bolts down a plasma pathway created by laser beams.
The pathway takes the form of an electrically conductive plasma channel that is formed when a laser beam of enough intensity (a 50 billion watt pulse lasting two-trillionths of a second will do) forms an electro-magnetic field strong enough to ionize the surrounding air to form plasma. Because the plasma channel conducts electricity much better than the non-ionized air that surrounds it, electrical energy will travel down the channel.
Then, when it hits its target – an enemy vehicle, person or unexploded ordnance, for example – the current will flow through the target as it follows the path of least resistance to the ground, potentially disabling the vehicle or person and detonating the ordnance. The lightning will also deviate from the channel when it gets close to the target and finds a lower-resistance path to the ground.
That’s the basic physics behind it, but overcoming the technical challenges to actually build the device won’t be easy.
"If the light focuses in air, there is certainly the danger that it will focus in a glass lens, or in other parts of the laser amplifier system, destroying it," said George Fischer, lead scientist on the project. "We needed to lower the intensity in the optical amplifier and keep it low until we wanted the light to self-focus in air.”
The research team also had to synchronize the laser with the high voltage and ruggedize the device so it could be operated under extreme environmental conditions. There is, of course, also the problem of providing enough power to operate the device for extended periods of time. Despite these challenges, the team claims to have made notable progress in recent months after reporting "excellent results" in tests conducted in January, 2012.
Work on the device is continuing.
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Laser weapon
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Lightning
I then turned my attention to wireless transmission and was fortunate enough to achieve similar success in this fruitful field, my discoveries and inventions being employed throughout the world. In the course of this work, I mastered the technique of high potentials sufficiently for enabling me to construct and operate, in 1899, a wireless transmitter developing up to twenty million volts. Some time before I contemplated the possibility of transmitting such high tension currents over a narrow beam of radiant energy ionizing the air and rendering it, in measure, conductive. After preliminary laboratory experiments, I made tests on a large scale with the transmitter referred to and a beam of ultra-violet rays of great energy in an attempt to conduct the current to the high rarefied strata of the air and thus create an auroral such as might be utilized for illumination, especially of oceans at night. I found that there was some virtue in the principal but the results did not justify the hope of important practical applications. [Tesla, Nikola, THE NEW ART OF PROJECTING CONCENTRATED NON-DISPERSIVE ENERGY THROUGH NATURAL MEDIA System of Particle Acceleration for Use in National Defense, circa May 16, 1935. (Reprinted in Nikola Tesla's Teleforce & Telegeodynamics Proposals, edited by Leland I. Anderson, Twenty-First Century Books, 1998, pp. 11-33.]
I also asked him if he is still at work on the project which he inaugurated in the '90's of transmitting power wirelessly anywhere on earth. He is at work on it, he said, and it could be put into operation. . . . He at that time announced two principles which could be used in this project. In one the ionizing of the upper air would make it as good a conductor of electricity as a metal. In the other the power is transmitted by creating "standing waves" in the earth by charging the earth with a giant electrical oscillator that would make the earth vibrate electrically in the same way a bell vibrates mechanically when it is struck with a hammer. "I do not use the plan involving the conductivity of the upper strata of the air," he said, "but I use the conductivity of the earth itself, and in this I need no wires to send electrical energy to any part of the globe." [“Tesla Cosmic Ray Motor May Transmit Power 'Round’ Earth,” Brooklyn Eagle, July 10, 1932.]
The Lightning Foundry is a project to build two 10-story (108-foot) high Tesla Coils that can generate arcs 260 feet in length. A fully functional 1:12 scale Lightning Foundry prototype is use to study the interactions between two matched coils. [Leyh, Greg. "Lightning Foundry Concept". Lightning on Demand. Nevada Lightning Laboratory.] The two identical 1:12 prototype coils were made by first winding a length of secondary wire onto a cardboard tube. The cardboard tube with the winding was then inserted into a corrugated plastic pipe and potted into place. Once the potting had set, the cardboard tube was removed, leaving the winding exposed inside of the pipe. The Lsec and Fo of the windings did not measurably change after potting. [Leyh, Greg. "Re: surface breakdown was Re: 20 joules at 100 bps vs 4 joules at 500 bps". Tesla Coil Mailing List. Chip Atkinson.] The 9-foot high twin coils show a strong tendency to wirelessly couple electrical energy over large distances. [Philipp, Joshua. "Largest Tesla Coils Ever Will Recreate Natural Lightning". TechZwn.] This ability is described in detail in a paper on wireless power transfer at the 2008 North American Power Symposium. [Leyh, G. E.; Kennan, M. D. (September 28, 2008). Efficient wireless transmission of power using resonators with coupled electric fields(PDF). NAPS 2008 40th North American Power Symposium, Calgary, September 28–30, 2008. Inst. of Electrical and Electronic Engineers. pp. 1–4. doi:10.1109/NAPS.2008.5307364. ISBN978-1-4244-4283-6. Retrieved November 20, 2014.]
Let's see if I understand this correctly. If you have radiation or electromagnetic waves going from your system, the energy is wasted?
Tesla
Absolutely wasted. From my circuit you can get either electromagnetic waves, 90 percent of electromagnetic waves if you like, and 10 percent in the current energy that passes through the earth. Or, you can reverse the process and get 10 percent of the energy in electromagnetic waves and 90 percent in energy of the current that passes through the earth.
It is just like this: I have invented a knife. The knife can cut with the sharp edge. I tell the man who applies my invention, you must cut with the sharp edge. I know perfectly well you can cut butter with the blunt edge, but my knife is not intended for this. You must not make the antenna give off 90 percent in electromagnetic and 10 percent in current waves, because the electromagnetic waves are lost by the time you are a few arcs around the planet, while the current travels to the uttermost distance of the globe and can be recovered.
This view, by the way, is now confirmed. Note, for instance, the mathematical treatise of Sommerfeld, who shows that my theory is correct, that I was right in my explanations of the phenomena, and that the profession was completely misled. This is the reason why these followers of mine in high frequency currents have made a mistake. They wanted to make high frequency alternators of 200,000 cycles with the idea that they would produce electromagnetic waves, 90 percent in electromagnetic waves and the rest in current energy. I only used low alternations, and I produced 90 percent in current energy and only 10 percent in electromagnetic waves, which are wasted, and that is why I got my results. [Cooper, Drury W., internal document of the law firm Kerr, Page & Cooper, New York City, 1916. (In Nikola Tesla On His Work With Alternating Currents and Their Application to Wireless Telegraphy, Telephony, and Transmission of Power, Leland I. Anderson, editor, Sun Publishing Company, 1992, p. 75.)]
Counsel
To illustrate your theory, I would like to know whether you consider that the radiation from any wireless station is wasted or conserved, or whether the effect produced by any of them today is due to this conductive action, so far as it is effective.
Tesla
Absolutely -- the effect at a distance is due to the current energy that flows through the surface layers of the earth. That has already been mathematically shown, really, by Sommerfeld. He agrees on this theory; but as far as I am concerned, that is positively demonstrated. For instance, take the Sayville antenna. Professor Zenneck took me out and gave me the particulars. I went over the calculations and found that at 36 kilowatts they were radiating 9 kilowatts in electromagnetic wave energy. They had, therefore, only 25 percent of the whole energy in these waves, and I told Professor Zenneck that this energy is of no effect -- that they produce, by the current, differences of potential in the earth, and these differences of potential are felt in Germany and affect the receiver. [Cooper, Drury W., internal document of the law firm Kerr, Page & Cooper, New York City, 1916. (In Nikola Tesla On His Work With Alternating Currents and Their Application to Wireless Telegraphy, Telephony, and Transmission of Power, Leland I. Anderson, editor, Sun Publishing Company, 1992, p. 133.)]
(The Telefunken alternator at Sayville had an initial frequency of 9,613 cycles per second. Two static frequency converters were used to double this to 19,266 and then 38,452 cycles per second [38.452 kHz], which was the station's transmitting frequency. It had a power output of 100 kilowatts, quite substantial for its day. [Bacon, Christopher (12 April 1996). "The Telefunken Sayville Wireless". Sayville History and Museums. Long Island Wireless Historical Society. Retrieved 26 December 2015.])
Tesla's claim that his system is different from Hertz‘s is based on the fact that at low frequencies, and with small antenna in terms of wavelength, radiation of Hertzian type electromagnetic wave is small. Tesla's waves, if we are allowed to use such a name, are in fact surface waves in modern terminology. . . . In "pure Hertzian" wave (in Tesla's terminology) there is no induced current in the Earth, except on reflection region which is not essential for the discussion. In contrast to the latter, guided surface or ELF waves do not exist without current in the Earth crust. Having this in mind, we can conclude that there is a truth in Tesla's statements about specific behavior of low frequency, guided to the Earth waves. As regards correctness of his approach to the propagation theory based on outlined assumptions, more study is needed and we hope that it will be done in the future. [Marinčić, Aleksandar (1990). "Research of Nikola Tesla in Long Island Laboratory," Energy and Development at the International Scientific Conference in Honor of the 130th Anniversary of the Birth of Nikola Tesla". The Tesla Journal, An International Review of the Sciences and the Humanities (Numbers 6 & 7). Tesla Memorial Society, Inc.: 25-28. Retrieved 1 November 2015. {{cite journal}}: |issue= has extra text (help)]
Interest in ground-wave propagation began with Sommerfeld's[l] analysis in 1909. Widespread utilization of these results, however, came with Norton's papers[2-4] which reduced Sommerfeld's complex expressions to graphs suitable for engineering applications and extended the results to spherical surfaces[5]. Since then, many investigators have made contributions which include a variety of deterministic surface geometries, including layers, surface-step discontinuities, propagation beyond hills (of given geometrical shape), knife-edge discontinuities, a layered atmosphere, and abrupt changes in surface properties (i.e., a shoreline model). For several recent reviews of the pertinent literature, one should consult the articles by Wait[6], Feinberg[7], Bremmer[8], Goubau[9], King[l0], and Wait[l1].
[1] Somerfeld, A., "The Propagation of Waves in Wireless Telegraphy", Ann, Physik, Vol 28, p 665 (1909).
[2] Norton, K. A., "The Propagation of Radio Waves Over the Surface of the Earth and in the Upper Atmosphere, Part I. Ground Wave Propagation From Short Antennas", Proc. IRE, Vol 24, p 1367 (1936).
[3] Norton, K. A., "The Propagation of Radio Waves Over the Surface of the Earth and in the Upper Atmosphere, Part II. The Propagation From Vertical, Horizontal, and Loop Antennas Over a Plane Earth of Finite Conductivity", Proc. IRE Vol 25, p. 1203 (1937).
[4] Norton, K. A., "The Physical Reality of Space and Surface Waves in the Radiation Field of Radio Antennas", Proc. IRE. Vol 25, p 1192 (1937).
[5] Norton, K. A., "The Calculation of Ground Wave Field Intensity Over a Finitely Conducting Spherical Earth", Proc. IRE, Vol 29, p 623 (1941).
[6] Wait, J. R., "The Propagation of Electromagnetic Waves Along the Earth's Surface", p 243, in Electromagnetic Waves, edited by R. Langer, University of Wisconsin Press: Madison, Wisconsin (1962).
[7] Feinberg, Ye. L., "Propagation of Radio Waves Along an Inhomogeneous Surface", Nuovo Cimento, Supplemento al Vol XI, Serie X, p 60 (1959).
[8] Brmmer, H., "Propagation of Electromagnetic Waves", p 423-639 (treatment of ground-wave propagation begins on p 515) in Handbuch der Physik, Vol 16 (1958).
[9] Goubau, G., "Waves on Interfaces", IRE Trans. Ant. Prop., Vol AP-7, p S140 (1959).
[10] King, R. J., "Electromagnetic Wave Propagation Over a Constant Impedance Plane", Radio Science, Vol 4, p 255 (1969).
[11] Wait, J. R., "Diffraction and Scattering of the Electromagnetic Ground Wave by Terrain Features", Radio Science, Vol 3, p 995 (1968).
[Barrick, Donald E., THEORY OF GROUND-WAVE PROPAGATION ACROSS A ROUGH SEA AT DEKAMETER WAVELENGTHS, Battelle Memorial Institute, Columbus Laboratories, AD865840, 1970.]
Despite the extensive literature on the propagation of electromagnetic waves over the earth’s surface, there still appears to be a need to clarify certain concepts. In particular, the distinction between what is usually regarded as a “surface wave” and the IEEE definition of “ground wave” is certainly not obvious. For convenience of discussion, these two definitions are quoted [l], [2].
1) “A surface wave is one that propagates along an interface between two different media without radiation; such radiation being construed to mean energy converted from the surface wave field to some other form."
2) "A radio wave that is propagated over the earth and is ordinarily affected by the presence of the ground and troposphere. The ground wave includes all components of a radio wave over the earth except ionospheric and tropospheric waves."
In studying the two references quoted, it is not evident how these two definitions can be reconciled with one another. The situation is particularly confused since in the IEEE Test procedures, the “surface wave” component of the ground wave is completely different from Professor Barlow’s definition quoted above.
[1] H. M. Barlow. “Defining a surface wave,” in Radio Waves and Circuits. S. Silver, Ed., Amsterdam: Elsevier Publ. Co., 1963, pp. 103-105.
[2] “IEEE Test Procedure for Antennas.” IEEE Trans. on Antennas and Propagation, pp. 437-566, May 1965.
[Wait, J. R., "A Note on Surface Waves and Ground Waves," IEEE Transactions on Antennas and Propagation, November 1965, pp. 996-997.]
The propagation of radio waves along the surface of the ground has been discussed from a theoretical standpoint for many years. As long ago as 1907, Zenneck [1] showed that a wave, which was a solution of Maxwell's equations, traveled without change of pattern over a flat surface bounding two homogeneous media of different conductivity and dielectric constants. When the upper medium is air and the lower medium is a homogeneous dissipative ground, the wave is characterized by a phase velocity greater than that of light and a small attenuation in the direction along the interface. Furthermore, this Zenneck surface wave, as it has been called, is highly attenuated with height above the surface. In 1909 Sommerfeld [2] solved the problem of a vertical dipole over a homogeneous ground (half-space). In an attempt to explain the physical nature of his solution, he divided the expression for the field into a "space wave" and a "surface wave." Both parts, according to Sommerfeld, are necessary in order to satisfy Maxwell's equations and the appropriate boundary conditions. The surface-wave part varied inversely as the square root of the range, and it was identified as the radial counterpart of the plane Zenneck surface wave.
[1] J. Zenneck, "Über die Fortpflanzung ebener elektromagnetischer Wellen längs einer ebenen Leiterfläche und ihre Beziehung zur drahtlosen Telegraphie," Ann. Physik [4] 23, 846 (1907). [2] A. Sommerfeld, "Uber die Ausbreitung der Wellen in der Drahtlosen Telegraphie" (The Propagation of Waves in Wireless Telegraphy), Ann. Physik [4] 28, 665 (1909); 62, 95 (1920); 81, 1135 (1926).
[Wait, James R., "Excitation of Surface Waves on Conducting, Stratified, Dielectric-Clad, and Corrugated Surfaces," Journal of Research of the National Bureau of Standards Vol. 59, No.6, December 1957.]
Sommerfeld saw a clear distinction between Hertzian waves and Zenneck surface waves, and he wanted to find out which physical phenomenon was occurring in real-world wireless telegraphy. Sommerfeld starts his paper by posing the following question:
Two contrasting concepts arise which may be designated by the terms 'space waves' and 'surface waves.' The Hertzian electrodynamic waves are [space waves]. Electrodynamic waves on wires are typical surface waves. . . . With which type are the waves utilized in wireless telegraphy to be identified? Are they like Hertzian waves in air or electrodynamic waves on wires? [11]
Sommerfeld briefly surveys Zenneck's work, and then identifies the primary purpose of his 1909 paper:
Heretofore there was no definite proof that such waves could be developed from waves coming from the transmitter. The main task of the present investigation is to give this proof and to settle the question: space waves or surface waves?
As Wait points out in an extensive tutorial review, Sommerfeld obtained exact expressions for the field components in the form of integrals which were then evaluated asymptotically.
In an attempt to explain the physical nature of his solution, he divided the expressions for the field into a 'space wave' and a 'surface wave'. Both parts, according to Sommerfeld, are necessary in order to satisfy Maxwell's equations and the appropriate boundary conditions. He found that the 'surface wave' part of the solution had almost identical properties to the plane Zenneck surface wave. The field amplitudes varied inversely as the square root of the horizontal distance from the source dipole. Furthermore it was a fast wave and it decayed exponentially with height above the interface. [112]
[11] Sommerfeld, Arnold N., “Uber die Ausbreitung der Wellen in der drahtlosen Telegraphie,” Annalen der Physik, March 16, 1909 (Vol. 28, No. 4), pp. 665-736.
[112] Wait, J. R., "Electromagnetic Surface Waves," in Advances in Radio Research, J.A Saxton, editor, Academic Press, Vol. 1, 1964, pp. 157-217. (See Corrections in Radio Science, Vol. 69D, #1, 1965, pp. 969-975.)
[Corum, Kenneth L.; Corum, James F. (1994). Nikola Tesla, Lightning Observations, and Stationary Waves, Appendix II, The Zenneck Surface Wave. CPG Communications. {{cite book}}: Cite has empty unknown parameters: |1= and |2= (help)]
Surface electromagnetic waves have been of research interest for over a century, starting with Zenneck’s formulation of a solution to Maxwell’s equations for a wave propagating on a surface with finite losses.1 Such surface waves have since been studied on a wide range of geometries and at frequencies spanning from the visible down to the radio spectral range.
1 H. M. Barlow and J. Brown, Radio Surface Waves Clarendon Press, Oxford, 1962; Surface Polaritons Electromagnetic Waves at Surfaces and Interfaces, edited by V. M. Agranovich and D. L. Mills, North-Holland, Amsterdam, 1982.
[Chau, K. J., A. Y. Elezzabi, "Effect of interface resistance on terahertz pulses in bimetallic microparticles," Phys. Rev. B 73, 085419, 23 February, 2006.]
However surprising, it is a fact that a [conducting] sphere of the size of a little marble offers a greater impediment to the passage of a current than the whole earth. . . . This is not merely a theory, but a truth established in numerous and carefully conducted experiments. [“The Future of the Wireless Art” Wireless Telegraphy & Telephony, Walter W. Massie & Charles R. Underhill, 1908, pp. 67-71]
Let us address the objection that, "The resistive earth losses [related to the resistance between the source and the antipode of the earth] are just too great for any of this to be seriously considered." [Corum, J. F.; Corum, K. L.; Daum, J. F. X. (1987). Spherical Transmission Lines and Global Propagation, An Analysis of Tesla's Experimentally Determined Propagation Model. CPG Communications. p. 3. {{cite book}}: |access-date= requires |url= (help)]
The analytical considerations are presented in Table I, where it is shown that the probable earth resistance is considerably less than 1 Ω. Even if the earth were effectively composed entirely of an insulator like Bakelite, never mind conductors like sea water or iron, the total earth resistance to the antipode and back would be less than 50 Ohms. [Corum, J. F.; Corum, K. L.; Daum, J. F. X. (1987). Spherical Transmission Lines and Global Propagation, An Analysis of Tesla's Experimentally Determined Propagation Model. CPG Communications. p. 4. {{cite book}}: |access-date= requires |url= (help)]
Tesla
I must first clear away some illusionary ideas. You must first understand certain things. Consider, for instance, the term "resistance." When you think of resistance you imagine, naturally, that you have a long, thin conductor; but remember that while resistance is directly proportionate to length, it is inversely proportionate to the section. It is a quality that depends on a ratio. If you take a small sphere of the same size of a pea, and compare its length with its section, you would find a certain resistance. Now you extend this pea to the size of the earth, and what is going to happen?
While the length increases, say a thousand times or a million times, the section increases with the square of the linear dimensions, so that the bigger this thing is the less resistance it has. Indeed, if the earth were as big as the sun we would still be better off than we are; we could readily telephone from one end of the sun to the other by the system, and the larger the planet the better it would be.
Counsel
Then do I get your idea correctly, that distance is of no importance because of the low resistance due to the large section of the earth?
Tesla
No, pardon me.
Counsel
I cannot quite get that. Why is it that with your system distance cuts no figure?
Tesla
Distance cuts no figure for the reason that there is no fall of potential. Now imagine this: Suppose that the earth, in reality, were a big main, a main of copper, say, that all the copper of the earth would be fused into a big main, and then you will readily see it would not make any difference where you tapped that energy, whether you do it nearby or whether you go 100 miles further, because the resistance of the main is nothing. The resistance of the earth does not come in in this way, but in another way. [Cooper, Drury W., internal document of the law firm Kerr, Page & Cooper, New York City, 1916. (In Nikola Tesla On His Work With Alternating Currents and Their Application to Wireless Telegraphy, Telephony, and Transmission of Power, Leland I. Anderson, editor, Sun Publishing Company, 1992, pp. 134-135.)]
The issue is not the resistance between the source and the antipode, but rather the so-called "ground bed resistance," i.e. - the electrical resistance between the ground bed and the conducting medium.[Corum, J. F.; Corum, K. L.; Daum, J. F. X. (1987). Spherical Transmission Lines and Global Propagation, An Analysis of Tesla's Experimentally Determined Propagation Model. CPG Communications. p. 4. {{cite book}}: |access-date= requires |url= (help)]
These questions are very complex. The resistance is only at the point where you get into the earth with your current. The rest is nothing. Those things will be very difficult to explain without a lot of theoretical stuff, which would be unprofitable, when it is here the object to give a clear idea of the principle and nothing else. [Cooper, Drury W., internal document of the law firm Kerr, Page & Cooper, New York City, 1916. (In Nikola Tesla On His Work With Alternating Currents and Their Application to Wireless Telegraphy, Telephony, and Transmission of Power, Leland I. Anderson, editor, Sun Publishing Company, 1992, pp. 134-135.)]
I also asked him if he is still at work on the project which he inaugurated in the '90's of transmitting power wirelessly anywhere on earth. He is at work on it, he said, and it could be put into operation. . . . He at that time announced two principles which could be used in this project. In one the ionizing of the upper air would make it as good a conductor of electricity as a metal. In the other the power is transmitted by creating "standing waves" in the earth by charging the earth with a giant electrical oscillator that would make the earth vibrate electrically in the same way a bell vibrates mechanically when it is struck with a hammer. "I do not use the plan involving the conductivity of the upper strata of the air," he said, "but I use the conductivity of the earth itself, and in this I need no wires to send electrical energy to any part of the globe." [“Tesla Cosmic Ray Motor May Transmit Power 'Round’ Earth,” Brooklyn Eagle, July 10, 1932.]
If you go high enough, the conductivity is so great that horizontally there is no more chance for voltage variations. The air, for the scale of times that we are talking about, becomes effectively a conductor. This occurs at a height in the neighborhood of 50 kilometers. This is not as high as what is called the "ionosphere," in which there are very large numbers of ions produced by photoelectricity from the sun. Nevertheless, for our discussions of atmospheric electricity, the air becomes sufficiently conductive at about 50 kilometers that we can imagine that there is practically a perfect conducting surface at this height, from which the currents come down. [Feynman, Richard P., Robert B. Leighton and Matthew Sands, The Feynman Lectures on Physics, Addison–Wesley Publishing Company, 1964.]
Existing:
Tesla demonstrated wireless power transmission at Colorado Springs, lighting incandescent electric lamps positioned relatively close to the structure housing his large experimental magnifying transmitter[1] and claimed afterwards that he had, "carried on practical experiments in wireless transmission."[2] He believed that he had achieved Earth electrical resonance at Colorado Springs that, according to his theory, would produce electrical effects at any terrestrial distance.[3]
There is no documented evidence that Tesla transmitted significant power beyond those short-range demonstrations[4][5][6][7][8][9][10][11][12][13] adjacent to the transmitter, perhaps 300 feet (91 m). Tesla biographer Marc Seifer notes opinions amongst researchers that range from the industrial wireless power transmission idea not being practicable to statements that the basic Tesla wireless system itself is viable, that Tesla's claim to have measured a terrestrial pulse that rebounded off the antipode of the earth is valid, and that his calculated fundamental earth resonance frequency is essentially correct. [14] Other investigators believe Tesla over estimated the conductivity of the Earth and the atmosphere and underestimated the loss of power over distance.[5][6][10][12][15][16][17][18][19] There is little indication that Tesla transmitted energy over significant distances by means of his system. The only report of long distance transmission by Tesla, from a 1916 interview, is that in 1899 he measured the transmitted energy over a distance of about 10 miles (16 km).[20]
Tesla demonstrated wireless power transmission at Colorado Springs, lighting incandescent electric lamps positioned relatively close to the structure housing his large experimental magnifying transmitter (recorded in the "The Problem of Increasing Human Energy" article published in Century Magazine, June 1900 and claimed afterwards that he had, "carried on practical experiments in wireless transmission." [Electrocraft - Volume 6 - 1910, Page 389]). He believed that he had achieved Earth electrical resonance at Colorado Springs that, according to his theory, would produce electrical effects at any terrestrial distance. [W. Bernard Carlson, Tesla: Inventor of the Electrical Age, Princeton University Press - 2013, page 301.]
Referring to the different instrumentalities described as being used by you for supplying sustained electrical oscillations to an antenna of high capacity and tuned to the frequency of the current impressed, for the transmission of energy without wires, what, if any, difference in principle was involved in the transmitting of such energy to a distant telephone, for instance, or for signaling, as compared with such transmission to any other form of translating device, such for instance, as a lamp?
Tesla
There is no difference whatever that I can see in the principle.
Counsel
Was there any difference in the equipment employed for these two purposes?
Tesla
Absolutely none that I can see. [Cooper, Drury W., internal document of the law firm Kerr, Page & Cooper, New York City, 1916. (In Nikola Tesla On His Work With Alternating Currents and Their Application to Wireless Telegraphy, Telephony, and Transmission of Power, Leland I. Anderson, editor, Sun Publishing Company, 1992, p. 145.)]
When I spoke of these enormous potentials, I was describing an industrial plant on a large scale because that was the most important application of these principles, but I have also pointed out in my patents that the same principles can be applied to telegraphy and other purposes.That is simply a question of how much power you want to transmit. [Cooper, Drury W., internal document of the law firm Kerr, Page & Cooper, New York City, 1916. (In Nikola Tesla On His Work With Alternating Currents and Their Application to Wireless Telegraphy, Telephony, and Transmission of Power, Leland I. Anderson, editor, Sun Publishing Company, 1992, p. 171-172.)]
There is no documented evidence Tesla ever transmitted significant power beyond those short-range demonstrations adjacent to the transmitter, perhaps 300 feet (91 m) [citation needed]. The writer Marc Seifer noted opinion amongst Tesla proponents that ranged from the idea not being practicable to claims some of Tesla's observations were valid. [Marc Seifer, Wizard: The Life and Times of Nikola Tesla - page 471-472.] Other investigators note that Tesla seemed over estimated the conductivity of the Earth and the atmosphere and vastly underestimated the drop in loss of power over distance.
There is also little evidence that Tesla achieved wireless communication over significant distances. The only report of long distance communication by Tesla, from a legal statement he made in 1916, is that in 1899 he transmitted a signals over a distance of about 10 miles (16 km) (Legal statement by Tesla to attorney Drury W. Cooper, from 1916 internal document of the law firm Kerr, Page & Cooper, New York City, cited in Anderson, 1992).
In 1990, Tesla biographer Marc Seifer gathered statements from Dr. Alexandar Marinčić, former director of the Nikola Tesla Museum, Belgrade, engineer historian Leland I. Anderson, large Tesla coil builder Robert Golka, mathematician Eric Dollard, and electrical engineer Dr. James F. Corum, Ph.D., about the viability of the Tesla wireless system.
Dr. Marinčić, Mr. Anderson, and Mr. Golka expressed the opinion that global transmission of electrical energy at industrial power levels would not be "practicable".
Both Mr. Dollard and Dr. Corum concluded that the Tesla wireless system apparatus is "viable". Dr. Corum further asserted that Tesla's claim to have measured a terrestrial pulse that rebounded off the antipode of the earth is "valid" and that his calculated earth resonance frequency is essentially correct. [Marc Seifer, Wizard: The Life and Times of Nikola Tesla, pp. 471-472.]
"Today, Tesla’s exact plan for the site remains a mystery even as scientists agree on the impracticality of his overall vision. The tower could have succeeded in broadcasting information, but not power." [Broad, William J. (May 4, 2009). "A Battle to Preserve a Visionary’s Bold Failure". New York Times (New York: The New York Times Co.). pp. D1.]
im·prac'ti·cal'i·ty (-kal'i-te), im·prac'ti·cal·ness n.
im·prac·ti·cal
(im-prak'ti-kəl) adj.
1. Unwise to implement or maintain in practice: Refloating the sunken ship proved impractical because of the great expense.
2. Incapable of dealing efficiently with practical matters, especially finances.
3. Not a part of experience, fact, or practice; theoretical.
4. Impracticable. See Usage Note at impracticable.
im·prac·ti·ca·ble
(im-prak'ti-kə-bəl) adj.
1. Impossible to do or carry out: Refloating the sunken ship intact proved impracticable because of its fragility.
2. Unfit for passage: roads impracticable in winter.
3. Archaic Unmanageable; intractable.
Usage Note: The adjective impracticable applies to a course of action that is impossible to carry out or put into practice; impractical, though it can be used in this way, also can be weaker in sense, suggesting that the course of action would yield an insufficient return or would have little practical value. A plan for a new stadium may be rejected as impracticable if the site is too marshy to permit safe construction, but if the objection is that the site is too remote for patrons to attend games easily, the plan is better described as impractical. See Usage Note at practicable.
Referring to the different instrumentalities described as being used by you for supplying sustained electrical oscillations to an antenna of high capacity and tuned to the frequency of the current impressed, for the transmission of energy without wires, what, if any, difference in principle was involved in the transmitting of such energy to a distant telephone, for instance, or for signaling, as compared with such transmission to any other form of translating device, such for instance, as a lamp?
Tesla
There is no difference whatever that I can see in the principle.
Counsel
Was there any difference in the equipment employed for these two purposes?
Tesla
Absolutely none that I can see. [Cooper, Drury W., internal document of the law firm Kerr, Page & Cooper, New York City, 1916. (In Nikola Tesla On His Work With Alternating Currents and Their Application to Wireless Telegraphy, Telephony, and Transmission of Power, Leland I. Anderson, editor, Sun Publishing Company, 1992, p. 145.)]
When I spoke of these enormous potentials, I was describing an industrial plant on a large scale because that was the most important application of these principles, but I have also pointed out in my patents that the same principles can be applied to telegraphy and other purposes.That is simply a question of how much power you want to transmit. [Cooper, Drury W., internal document of the law firm Kerr, Page & Cooper, New York City, 1916. (In Nikola Tesla On His Work With Alternating Currents and Their Application to Wireless Telegraphy, Telephony, and Transmission of Power, Leland I. Anderson, editor, Sun Publishing Company, 1992, p. 171-172.)]
It has been suggested that Tesla underestimated the drop in loss of power over distance, that is to say, the attenuation of the transmitted electric field energy as a function of distance ( e-ad ).
The propagation of radio waves along the surface of the ground has been discussed from a theoretical standpoint for many years. As long ago as 1907, Zenneck [1] showed that a wave, which was a solution of Maxwell's equations, traveled without change of pattern over a flat surface bounding two homogeneous media of different conductivity and dielectric constants. When the upper medium is air and the lower medium is a homogeneous dissipative ground, the wave is characterized by a phase velocity greater than that of light and a small attenuation in the direction along the interface. Furthermore, this Zenneck surface wave, as it has been called, is highly attenuated with height above the surface. In 1909 Sommerfeld [2] solved the problem of a vertical dipole over a homogeneous ground (half-space). In an attempt to explain the physical nature of his solution, he divided the expression for the field into a "space wave" and a "surface wave." Both parts, according to Sommerfeld, are necessary in order to satisfy Maxwell's equations and the appropriate boundary conditions. The surface-wave part varied inversely as the square root of the range, and it was identified as the radial counterpart of the plane Zenneck surface wave.
[1] J. Zenneck, "Über die Fortpflanzung ebener elektromagnetischer Wellen längs einer ebenen Leiterfläche und ihre Beziehung zur drahtlosen Telegraphie," Ann. Physik [4] 23, 846 (1907). [2] A. Sommerfeld, "Uber die Ausbreitung der Wellen in der Drahtlosen Telegraphie" (The Propagation of Waves in Wireless Telegraphy), Ann. Physik [4] 28, 665 (1909); 62, 95 (1920); 81, 1135 (1926).
[Wait, James R., "Excitation of Surface Waves on Conducting, Stratified, Dielectric-Clad, and Corrugated Surfaces," Journal of Research of the National Bureau of Standards Vol. 59, No.6, December 1957.]
[Tesla's] proposed system was . . . inefficient. . . .
[Wheeler, L. P. (August 1943). "Tesla's contribution to high frequency". Electrical Engineering (IEEE) 62 (8): 355–357. doi:10.1109/EE.1943.6435874. ISSN 0095-9197.]
"Because the dimensions of the earth ionospheric wave guide, are so enormous, you can transmit power, but not very much power. . . . There are two ways of propagating [electric current without wires], . . . between the earth and the ionosphere [or] you forget the ionosphere, and the current is carried only by the earth. . . . The problem with both modes in terms of really sending a lot of energy is they attenuate a lot. When you have current, if the earth and the ionosphere were superconductors, wonderful, we'd be able to do it. But they are poor conductors. So what happens is a lot of energy goes into heating the ground or heating the ionosphere."
"Tesla's idea of propagation is perfectly valid."
["Dennis Papadopoulos interview". Tesla: Master of Lightning - companion site for 2000 PBS television documentary. PBS.org, US Public Broadcasting Service website. 2000.]
Wave transfer of information functions well with tiny energy levels of even micro-watts. But a typical light bulb of 100 Watts needs 100 million times greater energy transfer. This is physically possible, but there are side effects when that much energy is going in all directions. Broad area distributed, wireless electromagnetic power at levels used by a modern home will not happen. Furthermore, because of inefficiencies of traveling wave production and conversion, and our collective need for the world to be more efficient, not less, wireless power is a very local solution to specialized specific problems and will not replace wiring.
[Chathan Cooke, Principal Research Engineer, MIT Laboratory for Electromagnetic and Electrical Systems. (In Edison's Concrete Piano: Flying Tanks, Six-Nippled Sheep, Walk-On-Water Shoes, and 12 Other Flops From Great Inventors by Jean Wearing, ECW Press, 2009, p. 98.]
Some say Tesla over estimated the conductivity of the earth. And, it is said, he over estimated the conductivity of the atmosphere as well.
Tesla not only thought that the globe was a good conductor but that the moderate altitude atmospheric layers were excellent conductors. [Curty, Jari-Pascal; Declercq, Michel; Dehollain, Catherine; Joehl, Norbert (2006). Design and Optimization of Passive UHF RFID Systems. Springer. p. 4. ISBN0387447105.]
[Tesla was] wrong about a lot of things. His vision for wireless transmitters went well beyond modern applications. He envisioned his wireless transfer of energy would not only power households but "aerial machines . . . propelled around the earth without a stop and the sun's energy controlled to create lakes and rivers for motive purposes and transfonnation of arid deserts into fertile land. . . . [Wearing, Judy (2009). Edison's Concrete Piano: Flying Tanks, Six-Nippled Sheep, Walk-On-Water Shoes, and 12 Other Flops From Great Inventors. ECW Press. p. 98. ISBN1554905516.] [unreliable source?]
[Tesla's] error was in not realizing that both the ionosphere and earth were poor conductors, and that most of the transmitted energy would be burned up in heat losses. In addition, the transmitted power would radiate in every direction, causing still further losses. . . . both ways are very inefficient for transferring energy due to the mediums' low level of conductivity. [Wagner, John, Innovation: The Lessons of Nikola Tesla, Blue Eagle Group, 2008, p. 78.] [unreliable source?]
[Tesla] failed because of diffusion of the wireless power, which depends on the frequency of operation and the size of the transmitting antenna. He used an operating frequency of 150 kHz. [Tomar, Anuradha; Gupta, Sunil (July 2012). "Wireless power Transmission: Applications and Components". International Journal of Engineering Research & Technology 1 (5). ISSN 2278-0181.] [unreliable source?]
[Tesla] failed because the transmitted power was diffused in all directions using 150 kHz radiowaves. [Shinohara, Naoki (2014). Wireless Power Transfer via Radiowaves. John Wiley & Sons. p. 11. ISBN1118862961.] [unreliable source?]
The reason that it [the Tesla wireless system] won't work is because it is based on the original theory of radio transmission for communication purposes. Here, only a minute voltage is sufficient to convey information to the receiver. The most powerful radio transmitters ever built could generate intense fields in the proximity of the station. Yet within a few miles they were merely radio signals, albeit stronger than some. It is all governed by the immmutable laws of electromagnetic radiation. This law says that the strength of the field is inversely proportional to the square of the distance. [Coe, Lewis (2006). Wireless Radio: A History. McFarland. p. 112. ISBN0786426624.] [unreliable source?]
[Lewis,] 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. [Cooper, Drury W., internal document of the law firm Kerr, Page & Cooper, New York City, 1916. (In Nikola Tesla On His Work With Alternating Currents and Their Application to Wireless Telegraphy, Telephony, and Transmission of Power, Leland I. Anderson, editor, Sun Publishing Company, 1992, p. 133.)]
What was the distance of the receiver from the sending station in the Colorado test?
Tesla
Well, these distances were small, for the reason that they were merely intended to give me quantitative data.
Counsel
Could you give the number of miles, approximately?
Tesla
Oh, 10 miles or so. [Cooper, Drury W., internal document of the law firm Kerr, Page & Cooper, New York City, 1916. (In Nikola Tesla On His Work With Alternating Currents and Their Application to Wireless Telegraphy, Telephony, and Transmission of Power, Leland I. Anderson, editor, Sun Publishing Company, 1992, pp. 172-173.)]
These historical try Tesla came to the following results:
1. Upon removal of more than 600 miles between the transmitter and receiving station are wireless telegraphic and telephonic communications carried out with minimal effort. For these and similar experiments needed only a very small fraction of the oscillator output, which clearly proved that with very little force of consumption a few kilowatts unlimited distances could be overcome. Normally, the oscillator 200 KW power only worked with 0.2 to 5% of its capacity. The rectification of the shafts for the telephonic reception was carried out by small contact detectors could be carried in the pocket.
2. The power is transmitted wirelessly at distances was 15 miles [24 km] performed on which distances lamps and electric motors were operated wirelessly. Also in these experiments was the capacity of the oscillator only a small fraction of its overall performance loaded, namely up to 5%. This result provided good evidence that even with Tesla apparatus and system performed wireless power transmission to significant distances can be. [Boksan, Slavko, Nikola Tesla und sein Werk - und die Entwicklung der Elektrotechnik, der Hochfrequenz - und Hochspannungstechnik und der Radiotechnik (mit einem Geleitwort von Prof. Dr. F. Kiebitz), Wien, New York, Leipzig, Deutscher Verlag fur Jugend und Volk, 1932, pp. 237-238.]
After building one or two small stations, he started in 1897, at his own expense, a station of 200 kilowatts in Colorado. From this point in 1899 he transmitted power enough to light a lamp at 30 km [19 miles]. [Eccles, W. H., "Dr. Nikola Tesla," Nature, London, 13. II, 1943. p. 189. (Reprinted in Tribute to Nikola Tesla, Nikola Tesla Museum, Beograd, 1961.)]
Tesla, in addition to experiments with his gigantic current movements, as a means of establishing world-wide broadcasts and making a number of detectors for such use, tested his power transmission system at a distance of twenty-six miles (41 km) from his laboratory and was able to light two hundred incandescent lamps, of the Edison type, with electrical energy extracted from the earth while his oscillator was operating. These lamps consumed about fifty watts each. [O'Neill" O'Neill, John J. (1944). Prodigal Genius: The life of Nikola Tesla. Ives Washburn, Inc. p. 193.]
The Lightning Foundry is a project to build two 10-story (108-foot) high Tesla Coils that can generate arcs 260 feet in length. A fully functional 1:12 scale Lightning Foundry prototype is use to study the interactions between two matched [Tesla] coils.[Leyh, Greg. "Lightning Foundry Concept". Lightning on Demand. Nevada Lightning Laboratory.] The two identical 1:12 prototype coils were made by first winding a length of secondary wire onto a cardboard tube. The cardboard tube with the winding was then inserted into a corrugated plastic pipe and potted into place. Once the potting had set, the cardboard tube was removed, leaving the winding exposed inside of the pipe. The Lsec and Fo of the windings did not measurably change after potting. [Leyh, Greg. "Re: surface breakdown was Re: 20 joules at 100 bps vs 4 joules at 500 bps". Tesla Coil Mailing List. Chip Atkinson.] The 9-foot high twin coils show a strong tendency to wirelessly couple electrical energy over large distances.[Philipp, Joshua. "Largest Tesla Coils Ever Will Recreate Natural Lightning". TechZwn.] This ability is described in detail in a paper on wireless power transfer at the 2008 North American Power Symposium.[Leyh, G. E.; Kennan, M. D. (September 28, 2008). Efficient wireless transmission of power using resonators with coupled electric fields(PDF). NAPS 2008 40th North American Power Symposium, Calgary, September 28–30, 2008. Inst. of Electrical and Electronic Engineers. pp. 1–4. doi:10.1109/NAPS.2008.5307364. ISBN978-1-4244-4283-6. Retrieved November 20, 2014.]
"Published on Oct 30, 2011, Mike Kennan driving his 'Tesla Roadster,' powered completely from the ambient fields produced by the Lightning Foundry 1:12 scale prototype coils. Note the sparking to the concrete, forming the return path. Video by Josh Bailey."
"Efficient Wireless Transmission of Power Using Resonators with Coupled Electric Fields," by G. E. Leyh and M. D. Kennan, Nevada Lightning Laboratory, http://lod.org/misc/Leyh/Papers/NAPS2008Final.pdf
“Tesla’s original patent [N. Tesla, "Apparatus for Transmission of Electrical Energy," U.S. Patent 649 621, May 15, 1900] resembles a far-field approach, given the large intended distance between stations compared to the station size. However, Tesla’s system minimizes radiated fields and instead relies upon actual conduction, replacing the transmission line with two non-wire conductors. In this case one conductor is the Earth, and the other appears to be either a capacitive path or a direct ionized path to the ionosphere according to different descriptions of the system.”
As it is described by U.S. Patent No. 649,621, APPARATUS FOR TRANSMISSION OF ELECTRICAL ENERGY, May 15, 1900, the Tesla wireless system relies upon electrical conduction, using two "non-wire" conductors. One conductor is Earth, and the other involves a capacitive or ionized path between the two air terminal electrodes.
“Of the designs mentioned above, the approach outlined in this paper is perhaps most similar to Tesla’s system, since it does not rely upon far-field or radiated power, or magnetic coupling. However this approach differs significantly from Tesla’s patented system in two important ways: A) There is no ionized path between the devices, and B) The receiver performs a synchronous detection of the received energy in order to optimize conversion efficiency. The transfer of energy in this approach occurs primarily through the electric fields between the receiver and transmitter.”
In the exact same manner as the Tesla wireless system, set forth in APPARATUS FOR TRANSMISSION OF ELECTRICAL ENERGY, the approach outlined in the Leyh-Kennan paper depends upon electrical conduction through the earth. It differs from the Tesla system as described in APPARATUS FOR TRANSMISSION OF ELECTRICAL ENERGY only in that, A) there is no highly ionized path between the Tesla coil transmitter and receiver, and B) the receiver performs a synchronous detection of the transmitted energy in order to optimize down-conversion efficiency. Tesla’s patents, ART OF TRANSMITTING ELECTRICAL ENERGY THROUGH THE NATURAL MEDIUMS, May 16, 1900, U.S. Patent No. 787,412, Apr. 18, 1905 and ART OF TRANSMITTING ELECTRICAL ENERGY THROUGH THE NATURAL MEDIUMS, Apr. 17, 1906, Canadian Patent No. 142,352, Aug. 13, 1912 do describe a means by which the Tesla wireless system can be operated without the necessity of an ionized path between the two devices, and also a means for synchronous detection of the transmitted energy.
"I'd always thought capacitive coupling such as in Tesla's wireless scheme to be a very weak effect, at best. However, faced with a burned grounding lead we set out to determine exactly how such amounts of power could be coupled across the room. We are now completely convinced that the power flowed through the ambient electric fields and returned through Earth, similar to Tesla’s original concept from 1900. Placing electric field shielding between the coils stopped 95% of the power flow."
"Mid-range [coupling] is defined as somewhere between one and ten times the diameter of the transmitting coil." "Typically, an inductive coupled system can transmit roughly the diameter of the transmitter." [Baarman, David W.; Schwannecke, Joshua (December 2009). "White paper: Understanding Wireless Power" (PDF). Fulton Innovation. pp. 2, 4.] "Strongly coupled magnetic resonance can work over the mid-range distance, defined as several times the resonator size." Agbinya (2012) Wireless Power Transfer, p. 40.]
"Mid-range [coupling] is defined as somewhere between one and ten times the diameter of the transmitting coil."
The Lightning Foundry Twin Coil Prototype coupling is greater than 21 times the diameter of the transmitting coil. [21][22][23][24]
^recorded in the "The Problem of Increasing Human Energy" article published in Century Magazine, June 1900
^ abWheeler, L. P. (August 1943). "Tesla's contribution to high frequency". Electrical Engineering. 62 (8). IEEE: 355–357. doi:10.1109/EE.1943.6435874. ISSN0095-9197.
^Brown, William C. (1984). "The history of power transmission by radio waves". MTT-Trans. on Microwave Theory and Technique. 32 (9). Inst. of Electrical and Electronic Engineers: 1230–1234. Retrieved November 20, 2014.
A resonant inductive coupling wireless power demonstration being performed at the Franklin Institute, Philadelphia, 1937. The vacuum tube oscillator (left) transmits electrical energy by magnetic induction to the resonant circuit receiver (right), lighting the bulb. Visitors could adjust the receiver's tuned circuits with the two knobs. When the resonant frequency of the receiver was out of tune with the transmitter, the light would go out.
"The resonant inductive coupling method that Tesla pioneered is now a familiar technology used throughout electronics and is currently being widely applied to short-range wireless power systems."
Reference: Leyh, G. E.; Kennan, M. D. (September 28, 2008). Efficient wireless transmission of power using resonators with coupled electric fields. NAPS 2008 40th North American Power Symposium, Calgary, September 28–30, 2008. Inst. of Electrical and Electronic Engineers. pp. 1–4. doi:10.1109/NAPS.2008.5307364. ISBN978-1-4244-4283-6.
The Lightning Foundry is a project to build two 10-story (108-foot) high Tesla Coils that can generate arcs 260 feet in length. A fully functional 1:12 scale Lightning Foundry prototype is use to study the interactions between two matched coils. [Leyh, Greg. "Lightning Foundry Concept". Lightning on Demand. Nevada Lightning Laboratory.] The two identical 1:12 prototype coils were made by first winding a length of secondary wire onto a cardboard tube. The cardboard tube with the winding was then inserted into a corrugated plastic pipe and potted into place. Once the potting had set, the cardboard tube was removed, leaving the winding exposed inside of the pipe. The Lsec and Fo of the windings did not measurably change after potting. [Leyh, Greg. "Re: surface breakdown was Re: 20 joules at 100 bps vs 4 joules at 500 bps". Tesla Coil Mailing List. Chip Atkinson.] The 9-foot high twin coils show a strong tendency to wirelessly couple electrical energy over large distances. [Philipp, Joshua. "Largest Tesla Coils Ever Will Recreate Natural Lightning". TechZwn.] This ability is described in detail in a paper on wireless power transfer at the 2008 North American Power Symposium. [Leyh, G. E.; Kennan, M. D. (September 28, 2008). Efficient wireless transmission of power using resonators with coupled electric fields(PDF). NAPS 2008 40th North American Power Symposium, Calgary, September 28–30, 2008. Inst. of Electrical and Electronic Engineers. pp. 1–4. doi:10.1109/NAPS.2008.5307364. ISBN978-1-4244-4283-6. Retrieved November 20, 2014.]
The Tesla's wireless system proposal came in two different 'flavors' described by some as being “closed” and “open” circuit. There is a 1932 newspaper article briefly describing them both.
I also asked him if he is still at work on the project which he inaugurated in the '90's of transmitting power wirelessly anywhere on earth. He is at work on it, he said, and it could be put into operation. . . . He at that time announced two principles which could be used in this project. In one the ionizing of the upper air would make it as good a conductor of electricity as a metal. In the other the power is transmitted by creating "standing waves" in the earth by charging the earth with a giant electrical oscillator that would make the earth vibrate electrically in the same way a bell vibrates mechanically when it is struck with a hammer. "I do not use the plan involving the conductivity of the upper strata of the air," he said, "but I use the conductivity of the earth itself, and in this I need no wires to send electrical energy to any part of the globe." [“Tesla Cosmic Ray Motor May Transmit Power 'Round’ Earth,” Brooklyn Eagle, July 10, 1932.]
U.S. Patent No. 645,576, SYSTEM OF TRANSMISSION OF ELECTRICAL ENERGY, and U.S. Patent No. 649,621, APPARATUS FOR TRANSMISSION OF ELECTRICAL ENERGY, both describe the 'closed circuit' method that, according to Tesla's theory, involves electrical conduction through upper atmospheric strata.
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 cannot travel along this curve and get there, but will be immediately transformed into conduction currents, and these currents will travel like currents over a wire with a return. The energy will be recovered in the circuit, not by a beam that passes along this curve and is reflected and absorbed, . . . but it will travel by conduction and will be recovered in this way. [Cooper, Drury W., internal document of the law firm Kerr, Page & Cooper, New York City, 1916. (In Nikola Tesla On His Work With Alternating Currents and Their Application to Wireless Telegraphy, Telephony, and Transmission of Power, Leland I. Anderson, editor, Sun Publishing Company, 1992, pp. 129-130).]
The second method is described in U.S. Patent #787,412, ART OF TRANSMITTING ELECTRICAL ENERGY THROUGH THE NATURAL MEDIUMS, and Ca. Patent #142,352, ART OF TRANSMITTING ELECTRICAL ENERGY THROUGH THE NATURAL MEDIUMS. In harmony with these patents it might be called the Earth resonance method, although, once again according to theory, a minimum Tesla coil transmitter power output of approximately 75 kW must be met for the electromagnetic wave energy to propagate globally and be reflected back, for the standing wave pattern to develop. At lower power levels there is no global propagation nor is there Earth resonance. This is the case with the small scale sub-global Tesla wireless system demonstration systems that Tesla wireless system researchers are working with, in which a passive Tesla coil receiving transformer is used to detect the transmitted energy. According to Tesla, the propagation is by means of “earth currents,” “currents through the globe,” or “current waves.” Furthermore, Tesla associates his theory of propagation with a theory developed by Arnold Sommerfeld.
From my circuit you can get either electromagnetic waves, 90 percent of electromagnetic waves if you like, and 10 percent in the current energy that passes through the earth. Or, you can reverse the process and get 10 percent of the energy in electromagnetic waves and 90 percent in energy of the current that passes through the earth.
It is just like this: I have invented a knife. The knife can cut with the sharp edge. I tell the man who applies my invention, you must cut with the sharp edge. I know perfectly well you can cut butter with the blunt edge, but my knife is not intended for this. You must not make the antenna give off 90 percent in electromagnetic and 10 percent in current waves, because the electromagnetic waves are lost by the time you are a few arcs around the planet, while the current travels to the uttermost distance of the globe and can be recovered.
This view, by the way, is now confirmed. Note, for instance, the mathematical treatise of Sommerfeld, who shows that my theory is correct, that I was right in my explanations of the phenomena, and that the profession was completely misled. This is the reason why these followers of mine in high frequency currents have made a mistake. They wanted to make high frequency alternators of 200,000 cycles with the idea that they would produce electromagnetic waves, 90 percent in electromagnetic waves and the rest in current energy. I only used low alternations, and I produced 90 percent in current energy and only 10 percent in electromagnetic waves, which are wasted, and that is why I got my results. [Cooper, Drury W., internal document of the law firm Kerr, Page & Cooper, New York City, 1916. (In Nikola Tesla On His Work With Alternating Currents and Their Application to Wireless Telegraphy, Telephony, and Transmission of Power, Leland I. Anderson, editor, Sun Publishing Company, 1992, p. 75.)]
And, there is this relating Earth current waves with what have been called “ground waves.”
Interest in ground-wave propagation began with Sommerfeld's analysis in 1909 (Somerfeld, A., "The Propagation of Waves in Wireless Telegraphy", Ann, Physik, Vol 28, p 665 (1909)). [Barrick, Donald E., THEORY OF GROUND-WAVE PROPAGATION ACROSS A ROUGH SEA AT DEKAMETER WAVELENGTHS, Battelle Memorial Institute, Columbus Laboratories, AD865840, 1970.]
We have this relating “ground waves” with “surface waves.”
Despite the extensive literature on the propagation of electromagnetic waves over the earth’s surface, there still appears to be a need to clarify certain concepts. In particular, the distinction between what is usually regarded as a “surface wave” and the IEEE definition of “ground wave” is certainly not obvious. For convenience of discussion, these two definitions are quoted:
“A surface wave is one that propagates along an interface between two different media without radiation; such radiation being construed to mean energy converted from the surface wave field to some other form. (H. M. Barlow. “Defining a surface wave,” in Radio Waves and Circuits. S. Silver, Ed., Amsterdam: Elsevier Publ. Co., 1963, pp. 103-105).
"A radio wave that is propagated over the earth and is ordinarily affected by the presence of the ground and troposphere. The ground wave includes all components of a radio wave over the earth except ionospheric and tropospheric waves." (“IEEE Test Procedure for Antennas.” IEEE Trans. on Antennas and Propagation, pp. 437-566, May 1965).
In studying the two references quoted, it is not evident how these two definitions can be reconciled with one another. The situation is particularly confused since in the IEEE Test procedures, the “surface wave” component of the ground wave is completely different from Professor Barlow’s definition quoted above. [Wait, J. R., "A Note on Surface Waves and Ground Waves," IEEE Transactions on Antennas and Propagation, November 1965, pp. 996-997.]
And we have this from Dr. Marinčić.
Tesla's claim that his system is different from Hertz‘s is based on the fact that at low frequencies, and with small antenna in terms of wavelength, radiation of Hertzian type electromagnetic wave is small. Tesla's waves, if we are allowed to use such a name, are in fact surface waves in modern terminology. In "pure Hertzian" wave (in Tesla's terminology) there is no induced current in the Earth, except on reflection region which is not essential for the discussion. In contrast to the latter, guided surface or ELF waves do not exist without current in the Earth crust. Having this in mind, we can conclude that there is a truth in Tesla's statements about specific behavior of low frequency, guided to the Earth waves. As regards correctness of his approach to the propagation theory based on outlined assumptions, more study is needed and we hope that it will be done in the future. [Marinčić, Aleksandar (1990). "Research of Nikola Tesla in Long Island Laboratory,” Energy and Development at the International Scientific Conference in Honor of the 130th Anniversary of the Birth of Nikola Tesla". The Tesla Journal, An International Review of the Sciences and the Humanities (Tesla Memorial Society, Inc.) (Numbers 6 & 7): 25-28. Retrieved 1 November 2015.]
Broadcasting and point-to-point wireless telecommunications
And would it also be necessary to provide for the high potentials of the order of which you have named in order to insure maximum direct currents and minimum electromagnetic wave radiation?
Tesla
No sir. The currents are proportionate to the potentials which are developed under otherwise equal conditions. If you have an antenna of a certain capacity charged to 100,000 volts, you will get a certain current; charged to 200,000 volts, twice the current. When I spoke of these enormous potentials, I was describing an industrial plant on a large scale because that was the most important application of these principles, but I have also pointed out in my patents that the same principles can be applied to telegraphy and other purposes.That is simply a question of how much power you want to transmit. [Cooper, Drury W., internal document of the law firm Kerr, Page & Cooper, New York City, 1916. (In Nikola Tesla On His Work With Alternating Currents and Their Application to Wireless Telegraphy, Telephony, and Transmission of Power, Leland I. Anderson, editor, Sun Publishing Company, 1992, p. 145.)]
As soon as completed, it will be possible for a business man in New York to dictate instructions, and have them instantly appear in type at his office in London or elsewhere. He will be able to call up, from his desk, and talk to any telephone subscriber on the globe, without any change whatever in the existing equipment. An inexpensive instrument, not bigger than a watch, will enable its bearer to hear anywhere, on sea or land, music or song, the speech of a political leader, the address of an eminent man of science, or the sermon of an eloquent clergyman, delivered in some other place, however distant. In the same manner any picture, character, drawing, or print can be transferred from one to another place. Millions of such instruments can be operated from but one plant of this kind [Wardenclyffe]. More important than this, however, will be the transmission of power, without wires, which will be shown on a scale large enough to carry conviction." [Massie, Walter W. and Charles R. Underhill, Wireless Telegraphy & Telephony, "The Future of the Wireless Art," 1908, pp. 67-71. (Reprinted in Tesla Said, edited by John Ratzlaff, Tesla Book Company, pp. 108-110.)]
Tesla did not break off his research in the field of radio after visiting Colorado Springs. Upon returning to New York on the 11th of January 1900 he took energetic steps to get backing for the implementation of a system of "World Telegraphy." He erected a building and an antenna on Long Island, and started fitting out a new laboratory. From his subsequent notes we learn that he intended to verify his ideas about resonance of the Earth's globe, referred to in a patent of 1900. [Marinčić, A., Nikola Tesla Colorado Springs Notes 1899-1900, Nolit, Belgrade, 1978.]
The first World System power plant can be put in operation in nine months. With this power plant it will be practical to attain electrical activities up to ten million horsepower and it is designed to serve for as many technical achievements as are possible without undue expense. Among these the following may be mentioned:
1. Interconnection of the existing telegraph exchanges of offices all over the World;
2. Establishment of a secret and non-interferable government telegraph service;
3. Interconnection of all the present telephone exchanges or offices all over the Globe;
4. Universal distribution of general news, by telegraph or telephone, in connection with the Press;
5. Establishment of a World System of intelligence transmission for exclusive private use;
6. Interconnection and operation of all stock tickers of the world;
7. Establishment of a world system of musical distribution, etc.;
8. Universal registration of time by cheap clocks indicating the time with astronomical precision and requiring no attention whatever;
9. Facsimile transmission of typed or handwritten characters, letters, checks, etc.;
10. Establishment of a universal marine service enabling navigators of all ships to steer perfectly without compass, to determine the exact location, hour and speed, to prevent collisions and disasters, etc.;
11. Inauguration of a system of world printing on land and sea;
12. Reproduction anywhere in the world of photographic pictures and all kinds of drawings or records.
Thus, more than forty years ago, Tesla planned to inaugurate every feature of modern radio, and several facilities which have not yet been developed. He was to continue, for another twenty years, to be the only "wireless" inventor who had yet visualized a broadcasting service. [O'Neill, John J., Prodigal Genius: The Life of Nikola Tesla, Ives Washburn, 1944.]
Let's see if I understand this correctly. If you have radiation or electromagnetic waves going from your system, the energy is wasted?
Tesla
Absolutely wasted. From my circuit you can get either electromagnetic waves, 90 percent of electromagnetic waves if you like, and 10 percent in the current energy that passes through the earth. Or, you can reverse the process and get 10 percent of the energy in electromagnetic waves and 90 percent in energy of the current that passes through the earth.
It is just like this: I have invented a knife. The knife can cut with the sharp edge. I tell the man who applies my invention, you must cut with the sharp edge. I know perfectly well you can cut butter with the blunt edge, but my knife is not intended for this. You must not make the antenna give off 90 percent in electromagnetic and 10 percent in current waves, because the electromagnetic waves are lost by the time you are a few arcs around the planet, while the current travels to the uttermost distance of the globe and can be recovered.
This view, by the way, is now confirmed. Note, for instance, the mathematical treatise of Sommerfeld, who shows that my theory is correct, that I was right in my explanations of the phenomena, and that the profession was completely misled. This is the reason why these followers of mine in high frequency currents have made a mistake. They wanted to make high frequency alternators of 200,000 cycles with the idea that they would produce electromagnetic waves, 90 percent in electromagnetic waves and the rest in current energy. I only used low alternations, and I produced 90 percent in current energy and only 10 percent in electromagnetic waves, which are wasted, and that is why I got my results. [Cooper, Drury W., internal document of the law firm Kerr, Page & Cooper, New York City, 1916. (In Nikola Tesla On His Work With Alternating Currents and Their Application to Wireless Telegraphy, Telephony, and Transmission of Power, Leland I. Anderson, editor, Sun Publishing Company, 1992, p. 75.)]
Counsel
To illustrate your theory, I would like to know whether you consider that the radiation from any wireless station is wasted or conserved, or whether the effect produced by any of them today is due to this conductive action, so far as it is effective.
Tesla
Absolutely -- the effect at a distance is due to the current energy that flows through the surface layers of the earth. That has already been mathematically shown, really, by Sommerfeld. He agrees on this theory; but as far as I am concerned, that is positively demonstrated. For instance, take the Sayville antenna. Professor Zenneck took me out and gave me the particulars. I went over the calculations and found that at 36 kilowatts they were radiating 9 kilowatts in electromagnetic wave energy. They had, therefore, only 25 percent of the whole energy in these waves, and I told Professor Zenneck that this energy is of no effect -- that they produce, by the current, differences of potential in the earth, and these differences of potential are felt in Germany and affect the receiver. [Cooper, Drury W., internal document of the law firm Kerr, Page & Cooper, New York City, 1916. (In Nikola Tesla On His Work With Alternating Currents and Their Application to Wireless Telegraphy, Telephony, and Transmission of Power, Leland I. Anderson, editor, Sun Publishing Company, 1992, p. 133.)]
That communication without wires to any point of the globe is practicable with such apparatus would need no demonstration, but through a discovery which I made I obtained absolute certitude. Popularly explained, it is exactly this: When we raise the voice and hear an echo in reply, we know that the sound of the voice must have reached a distant wall, or boundary, and must have been reflected from the same. Exactly as the sound, so an electrical wave is reflected, and the same evidence which is afforded by an echo is offered by an electrical phenomenon known as a "stationary" wave — that is, a wave with fixed nodal and ventral regions. Instead of sending sound-vibrations toward a distant wall, I have sent electrical vibrations toward the remote boundaries of the earth, and instead of the wall the earth has replied. In place of an echo I have obtained a stationary electrical wave, a wave reflected from afar. [THE PROBLEM OF INCREASING HUMAN ENERGY, Century Magazine, June 1900]
The discovery of the stationary terrestrial waves, showing that, despite its vast extent, the entire planet can be thrown into resonant vibration like a little tuning fork; that electrical oscillations suited to its physical properties and dimensions pass through it unimpeded, in strict obedience to a simple mathematical law, has proved beyond the shadow of a doubt that the earth, considered as a channel for conveying electrical energy, even in such delicate and complex transmissions as human speech or musical composition, is infinitely superior to a wire or cable, however well designed. [Tesla, N., "Tuned Lightning," English Mechanic and World of Science, March 8, 1907, pp. 107, 108.]
The measuring of standing waveforms from the electrical storms throughout July [1899] confirmed what he had suspected, namely, that the earth had a resonant frequency and could therefore be used as a carrier wave to transmit his signals. [Seifer, Marc (1996). "Ch. 27. Thor's Emmissary". Wizard: The Life and Times of Nikola Tesla, Biography of a Genius. Carol Publishing Group. p. 230. ISBN1-55972-329-7. Retrieved 10 November 2015.]
This problem was rendered extremely difficult, owing to the immense dimensions of the planet . . . but by gradual and continuous improvements of a generator of electrical oscillations . . . I finally succeeded in reaching electrical movements or rates of delivery of electrical energy not only approximately, but, as shown in comparative tests and measurements, actually surpassing those of lightning discharges . . . By the use of such a generator of stationary waves and receiving apparatus properly placed and adjusted in any other locality, however remote, it is practicable to transmit intelligible signals, or to control or actuate at will any one apparatus for many other important and valuable purposes. ["Tesla's Reply to Edison," English Mechanic and World of Science, July 14, 1905, p. 515, in Tesla Said, pp. 88-89, excerpted in Seifer, Marc (1996). "Ch. 27. Thor's Emmissary". Wizard: The Life and Times of Nikola Tesla, Biography of a Genius. Carol Publishing Group. p. 230. ISBN1-55972-329-7.]
This is certainly extraordinary for it shows more and more clearly that the earth behaves simply as an ordinary conductor and that it will be possible, with powerful apparatus, to produce the stationary waves which I have already observed in the displays of atmospheric electricity. [Marinčić, Aleksandar (1978). Nikola Tesla Colorado Springs Notes 1899–1900. Nolit. p. 103; July 24, 1899..]
Tesla's claim that his system is different from Hertz‘s is based on the fact that at low frequencies, and with small antenna in terms of wavelength, radiation of Hertzian type electromagnetic wave is small. Tesla's waves, if we are allowed to use such a name, are in fact surface waves in modern terminology. . . . In "pure Hertzian" wave (in Tesla's terminology) there is no induced current in the Earth, except on reflection region which is not essential for the discussion. In contrast to the latter, guided surface waves do not exist without current in the Earth crust. Having this in mind, we can conclude that there is a truth in Tesla's statements about specific behavior of low frequency, guided to the Earth waves. As regards correctness of his approach to the propagation theory based on outlined assumptions, more study is needed and we hope that it will be done in the future. [Marinčić, Aleksandar (1990). "Research of Nikola Tesla in Long Island Laboratory," Energy and Development at the International Scientific Conference in Honor of the 130th Anniversary of the Birth of Nikola Tesla". The Tesla Journal, An International Review of the Sciences and the Humanities (Numbers 6 & 7). Tesla Memorial Society, Inc.: 25-28. Retrieved 1 November 2015. {{cite journal}}: |issue= has extra text (help)]
The powerful electrical oscillations in the system E C D being communicated to the ground cause corresponding vibrations to be propagated to distant parts of the globe, whence they are reflected and by interference with the outgoing vibrations produce stationary waves the crests and hollows of which lie in parallel circles relatively to which the ground–plate E may be considered to be the pole. Stated otherwise, the terrestrial conductor is thrown into resonance with the oscillations impressed upon it just like a wire.
Three requirements seem to be essential to the establishment of the resonating condition.
First. The earth's diameter passing through the pole should be an odd multiple of the quarter wave length--that is, of the ratio between the velocity of light--and four times the frequency of the currents.
Second. It is necessary to employ oscillations in which the rate of radiation of energy into space in the form of hertzian or electromagnetic waves is very small . . . say smaller then twenty thousand per second, though shorter waves might be practicable. The lowest frequency would appear to be six per second, in which case there will be but one node, at or near the ground-plate.
Third. Irrespective of frequency the wave or wave-train should continue for a certain interval of time, estimated to be not less then one-twelfth or probably 0.08484 of a second [11.78 Hz] and which is taken in passing to and returning from the region diametrically opposite the pole. [ART OF TRANSMITTING ELECTRICAL ENERGY THROUGH THE NATURAL MEDIUMS, May 16, 1900, U.S. Patent No. 787,412, Apr. 18, 1905.]
In response to objections raised by U.S. Patent Examiner G.C. Dean regarding these three requirements, Tesla’s attorneys responded,
These three requirements, as stated are in agreement with his numerous experimental observations. . . . We would point out that the specification does not deal with theories, but with facts which applicant has experimentally observed and demonstrated again and again, and in the commercial exploitation of which he is engaged. [Corum, J. F.; Corum, K. L.; Daum, J. F. X. (1987). Spherical Transmission Lines and Global Propagation, An Analysis of Tesla's Experimentally Determined Propagation Model. CPG Communications. p. 3n. {{cite book}}: |access-date= requires |url= (help)]
I also asked him if he is still at work on the project which he inaugurated in the '90's of transmitting power wirelessly anywhere on earth.  He is at work on it, he said, and it could be put into operation. . . . He at that time announced two principles which could be used in this project. In one the ionizing of the upper air would make it as good a conductor of electricity as a metal. In the other the power is transmitted by creating "standing waves" in the earth by charging the earth with a giant electrical oscillator that would make the earth vibrate electrically in the same way a bell vibrates mechanically when it is struck with a hammer. "I do not use the plan involving the conductivity of the upper strata of the air," he said, "but I use the conductivity of the earth itself, and in this I need no wires to send electrical energy to any part of the globe." [“Tesla Cosmic Ray Motor May Transmit Power 'Round’ Earth,” Brooklyn Eagle, July 10, 1932.]
1891: Tesla demonstrates wireless energy transmission by means of electrostatic induction using a high-tension induction coil before the American Institute of Electrical Engineers at Columbia College.[1]
1893: Tesla demonstrates the wireless illumination of phosphorescent lamps of his design at the World's Columbian Exposition in Chicago.[2]
1893: Tesla demonstrates wireless energy transmission before a meeting of the National Electric Light Association in St. Louis.[3][4]using a grounded resonance transformer transmitter and a grounded resonance transformer receiver.[5][6]
1894: Tesla lights incandescent lamps wirelessly at the 35 South Fifth Avenue laboratory in New York City by means of "electro-dynamic induction" or resonant inductive coupling.[7][8][9]
1897: Tesla demonstrates wireless energy transmission over a distance of about 48 kilometres (30 mi).[10][11][12] Files his first patent applications dealing specifically with wireless transmission.
1899: Tesla shifts wireless power transmission research to Colorado Springs and writes, "the inferiority of the induction method would appear immense as compared with the disturbed charge of ground and air method."[13]
1900: Tesla receives patents APPARATUS FOR TRANSMISSION OF ELECTRICAL ENERGY and SYSTEM OF TRANSMISSION OF ELECTRICAL ENERGY.
1901: Tesla begins construction of the Wardenclyffe power plant and tower, a wireless signal and power transmitter in Shoreham, New York based on his ideas of ground and atmospheric electrical conductivity.[14] He runs out of money before the project can be completed,[15] with investors opting to invest in Marconi's radio system.[16]
1914: Tesla receives patent APPARATUS FOR TRANSMITTING ELECTRICAL ENERGY, Jan. 18, 1902, U.S. Patent 1,119,732, Dec. 1, 1914.
1916: Tesla states, "In my [disturbed charge of ground and air] system, you should free yourself of the idea that there is [electromagnetic] radiation, that energy is radiated. It is not radiated; it is conserved."[17]
^"Experiments With Alternating Currents of Very High Frequency, and Their Application to Methods of Artificial Illumination," Columbia College, 1891.
^"Electricity at the Columbian Exposition" By John Patrick Barrett. 1894. Page 168–169.
^"On Light and Other High Frequency Phenomena, Franklin Institute, Philadelphia, February 1893, and National Electric Light Association, St. Louis, March 1893
^"Nikola Tesla, 1856 – 1943". IEEE History Center, IEEE, 2003. lecture-demonstration St. Louis.
^Cheney, Margaret, Tesla Man Out of Time, Prentice-Hall, 1981, 1983, ISBN: 0-743-21536-2, page 68.
^"Electricity at the Columbian Exposition" By John Patrick Barrett. 1894. Page 168–169.
^Seifer, Marc J. (October 18–20, 2006). "Nikola Tesla and John Jacob Astor". SIXTH INTERNATIONAL SYMPOSIUM NIKOLA TESLA. Belgrade, SASA, Serbia. {{cite journal}}: |access-date= requires |url= (help)
In 1899 Tesla moved his wireless transmission research to Colorado Springs, Colorado to work out data for the construction of Wardenclyffe, a commercial wireless telecommunications facility to be built on Eastern Long Island, New York.[1]
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.
"Tesla did not start working on Wardenclyffe until after Nov 1900, despite his (primary sourced) claims he intended that all along."
^High Frequency Oscillators for Electrotherapeutic and Other Purposes (delivered before the American Electro-Therapeutic Association, Buffalo, September 13, 1898).
^Cooper, Drury W., internal document of the law firm Kerr, Page & Cooper, New York City, 1916
Nikola Tesla conducted the first experiments in wireless power transfer at the turn of the 20th century. From 1891 to 1898 he experimented with transmission of electrical energy using his radio frequencyresonant transformer called the Tesla coil, which produces high voltage, high frequency alternating currents.[1][2] With this basic resonance transformer design concept he was able to transfer power over short distances without interconnecting wires by means of resonant magnetic inductive coupling.[3][4] The transformer's primary LC circuit acted as a transmitter. The transformer's secondary LC circuit was tuned to the primary LC circuit's resonant frequency and acted as a receiver. The Tesla coil transformer itself could be configured as a wireless transmitter and used to transfer power by capacitive inductive coupling. While demonstrating this technology during lectures before the American Institute of Electrical Engineers in 1891, the Institution of Electrical Engineers in 1892, and at the 1893 Columbian Exposition in Chicago he was able to wirelessly power lamps from across the stage and throughout the hall.[5][6][7]
In 1899 Tesla shifted his wireless transmission research to Colorado Springs, Colorado to work out data for the construction of Wardenclyffe, a commercial wireless telecommunications facility to be built on Eastern Long Island, New York.[8] At the Colorado Springs Experimental Station he assembled an enormous magnifying transmitter capable of producing voltages on the order of 10 megavolts. In one demonstration, using just the primary circuit energized to only one-twentieth of the oscillator's capacity, he was able to light three incandescent lamps at a distance of about one hundred feet.[9][10] Such resonant inductive coupling is now familiar technology used throughout electronics and is currently being widely applied to short-range wireless power systems.[2] The magnetic and capacitive induction coupling techniques applied by Tesla during his early demonstrations incorporate "near-field" effects,[2] so, as he discovered, they are not useful for transferring power over long distances.
"While in Colorado he wrote, "the inferiority of the induction method would appear immense as compared with the disturbed charge of ground and air method."[11]
Tesla's priority was the development of a wireless power distribution system that could transmit electrical energy directly into homes and factories, as proposed in his 1900 Century magazine article.[12][13][14] He claimed that it is possible to transmit energy on a worldwide scale, applying a method that involves electrical conduction through the earth and the periodic alteration of Earth's electrostatic charge.[15][16][17] In 1900 Tesla received the patents SYSTEM OF TRANSMISSION OF ELECTRICAL ENERGY and APPARATUS FOR TRANSMISSION OF ELECTRICAL ENERGY.[18][19] They describe two hypothetical wireless stations consisting of a large Tesla coil magnifying transmitter and a similar Tesla coil receiver with their two elevated air terminal electrodes suspended with balloons at an altitude of 30,000 feet (9,100 m), where the atmospheric pressure is lower.[20] Tesla believed atmospheric ionization would allow energy to be transmitted at high voltages (millions of volts) over long distances by electrical conduction. Another claim was that such a high elevation of the air terminal electrodes is not absolutely necessary.[21] By 1901 Tesla had come to believe the entire planet could made to act as a giant electrical resonator and that by driving current pulses into Earth at a harmonic of its fundamental resonant frequency using a grounded Tesla coil working against a relatively short elevated capacitive air terminal electrode, its natural electrostatic potential could be made to oscillate, and this alternating current could be received at any location with a Tesla coil receiver and similar capacitive air terminal electrode arrangement tuned to resonance with the transmitter.[22][23]
In 1901, Tesla began construction of a large high-voltage wireless energy transmission station, now called the Wardenclyffe Tower, at Shoreham, New York. Promoted to investors as a transatlantic radiotelephony station, it was also intended to demonstrate small-scale wireless power transfer as a prototype transmitter for a "World Wireless" system that was to broadcast both information and power worldwide.[13][24] By 1904 his investors had pulled out and the facility was never completed.
^Cite error: The named reference Shinohara was invoked but never defined (see the help page).
^ abcLee, C.K.; Zhong, W.X.; Hui, S.Y.R. (September 5, 2012). Recent Progress in Mid-Range Wireless Power Transfer(PDF). The 4th Annual IEEE Energy Conversion Congress and Exposition (ECCE 2012). Raleigh, North Carolina: Inst. of Electrical and Electronic Engineers. pp. 3819–3821. Retrieved November 4, 2014.
^Cite error: The named reference Wheeler was invoked but never defined (see the help page).
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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.
^Cite error: The named reference Cheney was invoked but never defined (see the help page).
^Tesla was secretive about the distances he could transfer power. One of his few disclosures was in Tesla, Nikola (June 1900). "The Problem of Increasing Human Energy". Century Magazine. New York: The Century Co. The figure 7 caption reads:
"EXPERIMENT TO ILLUSTRATE AN INDUCTIVE EFFECT OF AN ELECTRICAL OSCILLATOR OF GREAT POWER – The photograph shows three ordinary incandescent lamps lighted to full candle-power by currents induced in a local loop consisting of a single wire forming a square of fifty feet each side, which includes the lamps, and which is at a distance of one hundred feet from the primary circuit energized by the oscillator. The loop likewise includes an electrical condenser, and is exactly attuned to the vibrations of the oscillator, which is worked at less than five percent of its total capacity."
Starting from two facts that the earth is a conductor insulated in space, and that a body cannot be charged without causing an equivalent displacement of electricity in the earth, I undertook to construct a machine suited for creating as large a displacement as possible of the earth's electricity.
^The Feynman Lectures on Physics, R.P. Feynman, R.B. Leighton, M. Sands, Addison-Wesley Publishing Co., 1964, Vol. 2, chapter 9.
^Cite error: The named reference US_Patent_645576 was invoked but never defined (see the help page).
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At that time I was absolutely sure that I could put up a commercial plant, if I could do nothing else but what I had done in my laboratory on Houston Street; but I had already calculated and found that I did not need great heights to apply this method. My patent says that I break down the atmosphere "at or near" the terminal. If my conducting atmosphere is 2 or 3 miles above the plant, I consider this very near the terminal as compared to the distance of my receiving terminal, which may be across the Pacific. That is simply an expression. I saw that I would be able to transmit power provided I could construct a certain apparatus -- and I have, as I will show you later. I have constructed and patented a form of apparatus which, with a moderate elevation of a few hundred feet, can break the air stratum down.
Hawkins makes no mention of any failure on the part of Tesla to perform experiments. Carlson refers only to Tesla’s not having demonstrated a completed system of global wireless telecommunications based upon the earth resonance principle while working at the Colorado Springs Experimental Station. It is noted that the Wardenclyffe facility was intended for this very purpose.
"There seems to be no evidence that he ever transmitted significant power beyond the short-range demonstrations above . . ."[1][2][3][4][5][6][7][8][9]
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This 300 foot figure is incorrect. The actual distance should appear as, 1938 feet, "far out in the field."[1]
"During his eight month stay at Colorado Springs Tesla carried out a series of experiments with his spark-discharge oscillator. . . . In September 1899 he succeeded in lighting a lamp of approximately 10 W "placed far out into the field," the exact distance from the ground plate being indicated in the Colorado Springs Notes, in the introductory comment for that month.""Sept. 9. Experiments to be made with st. waves. Exact distance measured to point from ground plate 1938 ft."[1]
"The only report of long-distance transmission by Tesla is a claim, not found in reliable sources, that in 1899 he wirelessly lit 200 light bulbs at a distance of 26 miles (42 km)."[1][2]
^Cite error: The named reference Cheney was invoked but never defined (see the help page).
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"There is no independent confirmation of this putative demonstration;"[1][2][3]
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The only known report of the long-distance transmission and reception of electrical energy by Tesla himself is a statement made to attorney Drury W. Cooper in 1916 that in 1899 he collected quantitative transmission-reception data at a distance of about 10 miles (16 km).[1][2]
^Cite error: The named reference Cooper_1916 was invoked but never defined (see the help page).
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There are four reports by others of Tesla having achieved long-distance wireless power transfer.
The first is the wireless operation of lamps and electric motors at a distance of 15 miles (24 km).[1]
The second is the wireless transfer of "power enough to light a lamp at 30 km [19 miles].[1]
^Eccles, W. H. (1943). "Dr. Nikola Tesla". Nature. 13 (II). London: 189. (Reprinted in W. H. Eccles (1961). Tribute to Nikola Tesla. Beograd: Nikola Tesla Museum. {{cite book}}: |access-date= requires |url= (help))
The third is an assertion by Tesla biographer John J. O'Neill,[1] said to be pieced together from "fragmentary material . . . in a number of publications,"[2] that in 1899 Tesla lit 200 incandescent lamps at a distance of 26 miles (42 km).[3][1] There is no independent confirmation of this demonstration.[3][1][4] Tesla did not mention it,[3] and it does not appear in his Colorado laboratory notes.[4][5]
^ abcCite error: The named reference Cheney_1981 was invoked but never defined (see the help page).
^Tesla, Nikola; Marincic, Aleksandar, Ed. (1977). Colorado Springs Notes, 1899-1900. Beograd, Yugoslavia: The Nikola Tesla Museum.{{cite book}}: CS1 maint: multiple names: authors list (link)
The fourth is the wireless transfer of sufficient power to light an incandescent lamp of approximately 10 W at a distance of 1,938 feet (591 m) from the magnifying transmitter's ground plate to the point of reception.[1]
"In the 110 years since Tesla's experiments, efforts using similar equipment have failed to achieve long distance power transmission,"[1][2][3][4]
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Over one-hundred years have passed since his original work and there is no documentation of the Tesla wireless system apparatus ever having been replicated, other than by Leyh and Kennan,[1] and no published reports exist of any attempt to achieve long distance wireless energy transfer by this means.[2][3][4][5]
^Cite error: The named reference Leyh-Kennan was invoked but never defined (see the help page).
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^"Dennis Papadopoulos interview". Tesla: Master of Lightning - companion site for 2000 PBS television documentary. PBS.org, US Public Broadcasting Service website. 2000. Retrieved November 19, 2014.[unreliable source?]
"Tesla's world power transmission scheme remains today what it was in Tesla's time, a fascinating dream."[1][2]
^Cite error: The named reference Tomar was invoked but never defined (see the help page).
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Modern demonstrations have validated the basic concept of Tesla's wireless energy transmission scheme over medium range distances[1]
^Cite error: The named reference Leyh-Kennan was invoked but never defined (see the help page).
and mathematical analysis suggest the feasibility of long distance wireless telecommunications by its means.[1][2][3][4][5]
^Corum, K. L., J. F. Corum, J. F. X. Daum, “Spherical Transmission Lines and Global Propagation, An Analysis of Tesla's Experimentally Determined Propagation Model," 1987.
^Corum, K. L. and J. F. Corum, "Nikola Tesla, Lightning Observations, and Stationary Waves," 1994.
^ Corum, K. L., J. F. Corum, and A. H. Aidinejad, "Atmospheric Fields, Tesla's Receivers and Regenerative Detectors," 1994.
^Corum, K. L. and J. 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.
^ Corum, K. L. and J. F. Corum, "The Schumann Cavity, J. J. Thomson's Spherical Resonators and the Gateway to Modern Physics, " 1996.
Many of the roots that nourished the work of the Hammond group and its contemporaries were recorded in our paper: the pioneering work of Wilson and Evans, Tesla, Shoemaker, in basic radiodynamics; of Edison, Fleming, De Forest in basic electronics; of Tesla and Fessenden leading to the development of basic intermediate frequency circuitry. [Espenschied, Lloyd (July 1959). "Comments on Discussion of A History of Some Foundations of Modern Radio-Electronic Technology"(PDF). Proceedings of the IRE (Vol. 47, No. 7): 1254, 1256. {{cite journal}}: |issue= has extra text (help)]
A review of recent experimental and analytical research into the sensitive detector circuits used by Tesla during his famous lightning observation experiments in Colorado Springs. Reconstructed models of Tesla's 1899 apparatus reveal an unanticipated level of sophistication (his coherer circuits include distributed high-Q helical resonators, RF feedback, primitive heterodyne and regeneration techniques). [Corum, Kenneth L.; Corum, James F.; Aidinejad, A. H. (1994). Nikola Tesla, Atmospheric Fields, Radio Receivers, and Regenerative Detectors Atmospheric Fields, Tesla's Receivers and Regenerative Detectors(PDF). p. 44. {{cite book}}: Cite has empty unknown parameters: |1= and |2= (help)CS1 maint: multiple names: authors list (link)
ref name="Anderson_1992"
Anderson, Leland I. (1992). In Nikola Tesla On His Work With Alternating Currents and Their Application to Wireless Telegraphy, Telephony, and Transmission of Power. Sun Publishing Company.
ref name="Kerr"
Cooper, Drury W. (1916). "Marconi Wireless Telegraph Company of America v. Atlantic Communication Company, et al., Pre-hearing Interview Transcript". Kerr, Page & Cooper, New York City. {{cite journal}}: Cite journal requires |journal= (help)
ref name="Cohen"
Cohen, Samuel D (Feb. 1917). "Dr. Nikola Tesla and His Achievements". The Electrical Experimenter: 712, 713, 777. {{cite journal}}: Check date values in: |date= (help)
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Espenschied, Lloyd (July 1959). "Comments on Discussion of A History of Some Foundations of Modern Radio-Electronic Technology"(PDF). Proceedings of the IRE (Vol. 47, No. 7): 1254, 1256. {{cite journal}}: |issue= has extra text (help)
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Corum, Kenneth L.; Corum, James F., Aidinejad, A. H. (1994). Nikola Tesla, Atmospheric Fields, Radio Receivers, and Regenerative Detectors Atmospheric Fields, Tesla's Receivers and Regenerative Detectors(PDF). CPG Communications. {{cite book}}: Cite has empty unknown parameters: |1= and |2= (help)CS1 maint: multiple names: authors list (link)
16. "short", "midrange", and "long range" are defined below 23. "Typically, an inductive coupled system can transmit roughly the diameter of the transmitter."(p. 4) "...mid-range is defined as somewhere between one and ten times the diameter of the transmitting coil."(p. 2) Baarman, David W.; Schwannecke, Joshua (December 2009). "White paper: Understanding Wireless Power" (PDF). Fulton Innovation. Retrieved January 3, 2015.
24. "...strongly coupled magnetic resonance can work over the mid-range distance, defined as several times the resonator size." Agbinya (2012) Wireless Power Transfer, p. 40
ref name="Corum_1987"
Corum, J. F.; Corum, K. L.; Daum, J. F. X. (1987). Spherical Transmission Lines and Global Propagation, An Analysis of Tesla's Experimentally Determined Propagation Model. CPG Communications. Retrieved 9 November 2015.
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Corum, J. F.; Corum, K. L. (1988). "Tesla Coils--An RF Power Processing Tutorial for Engineers". In Elswick, S. R. (ed.). Proceedings of the 1988 International Tesla Symposium. International Tesla Society. {{cite book}}: |access-date= requires |url= (help)
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Corum, J. F.; Corum, K. L. (1990). "100 Years of Cavity Resonator Development". In Elswick, S. R. (ed.). Proceedings of the 1990 International Tesla Symposium. International Tesla Society. {{cite book}}: |access-date= requires |url= (help)
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Corum, J. F.; Corum, K. L. (1990). "A Rediscovery of Tesla's RF Techniques". In Elswick, S. R. (ed.). Proceedings of the 1990 International Tesla Symposium. International Tesla Society. {{cite book}}: |access-date= requires |url= (help)
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Corum, J. F.; Corum, K. L. (1992). "Tesla and the Magnifying Transmitter". In Elswick, S. R. (ed.). Proceedings of the 1992 International Tesla Symposium. International Tesla Society. {{cite book}}: |access-date= requires |url= (help)
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Corum, J. F.; Corum, K. L.; Daum, J. F. X. (May 1992). "Tesla Coil Research"(PDF). Contractor Report ARCCD-CR-92006. AD-A28 2 289. AD-E402-343. Defense Technical Information Center. Retrieved 9 November 2015.
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Corum, Kenneth L.; Corum, James F. (1994). Nikola Tesla, Lightning Observations, and Stationary Waves. CPG Communications. {{cite book}}: Cite has empty unknown parameters: |1= and |2= (help)
ref name="Corum_1994b"
Corum, Kenneth L.; Corum, James F., Aidinejad, A. H. (1994). Nikola Tesla, Atmospheric Fields, Radio Receivers, and Regenerative Detectors Atmospheric Fields, Tesla's Receivers and Regenerative Detectors(PDF). CPG Communications. {{cite book}}: Cite has empty unknown parameters: |1= and |2= (help)CS1 maint: multiple names: authors list (link)
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Corum, Kenneth L.; Corum, James F. (1996). Nikola Tesla and the Diameter of the Earth: A Discussion of One of the Many Modes of Operation of the Wardenclyffe Tower. CPG Communications. {{cite book}}: Cite has empty unknown parameters: |1= and |2= (help)
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Corum, J. F.; Corum, K. L. "RF Coils, Helical Resonators and Voltage Magnification by Coherent Spatial Modes". TELSIKS 2001. 1 (5th International Conference on Telecommunications in Modern Satellite, Cable and Broadcasting Service). IEEE: 339–348. Retrieved 9 November 2015.
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Corum, J. F.; Corum, K. L. (September 2001). "RF Coils, Helical Resonators and Voltage Magnification by Coherent Spatial Modes"(PDF). Microwave Review. IEEE: 36–45. Retrieved 9 November 2015.
