World Wireless System

The World Wireless System was a turn of the 20th 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. He claimed this system would allow for "the transmission of electric energy without wires" on a global scale 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 he had convinced banker J. P. Morgan to finance construction of a wireless station (eventually sited at Wardenclyffe, Long Island, New York) based on his ideas intended to transmit messages across the Atlantic to England and to ships at sea. His decision to change the design to include wireless power transmission to better compete with Guglielmo Marconi's new radio based telegraph system was met with Morgan's refusal to fund the changes. The project 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. He would continue to elaborate to the press and in his writings for the next few decades on the system's capabilities and how it was superior to radio-based systems. Despite claims of having "carried on practical experiments in wireless transmission", 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.

History

Origins Tesla's ideas for a World Wireless system grew out of experiments beginning in the early 1890s after learning of Hertz's experiments with electromagnetic waves using induction coil transformers and spark gaps. He duplicated those experiments and then went on to improve Hertz's wireless transmitter, developing various alternator apparatus and his own high tension transformer, known as the Tesla coil. His primary interest in wireless phenomenon was as a power distribution system, early on pursuing wireless lighting. From 1891 on Tesla was delivering lectures including "Experiments with Alternate Currents of High Potential and High Frequency" in 1892 in London, England and in Paris, France and went on to demonstrate "wireless lighting" in 1893 including lighting Geissler tubes wirelessly.

One-wire transmission The first experiment was the operation of light and motive devices connected by a single wire to one terminal of a high frequency induction coil, performed during the 1891 New York City lecture at Columbia College. While a single terminal incandescent lamp connected to one of an induction coil's secondary terminals does not form a closed circuit "in the ordinary acceptance of the term" the circuit is closed in the sense that a return path is established back to the secondary by capacitive coupling or 'displacement current'. This is due to the lamp's filament or refractory button capacitance relative to the coil's free terminal and environment; the free terminal also has capacitance relative to the lamp and environment.

Wireless transmission The second result demonstrated how energy can be made to go through space without any connecting wires. The wireless energy transmission effect involves the creation of an electric field between two metal plates, each being connected to one terminal of an induction coil's secondary winding. A gas discharge tube was used as a means of detecting the presence of the transmitted energy. Some demonstrations involved lighting of two partially evacuated tubes in an alternating electrostatic field while held in the hand of the experimenter.

Development

While formulating his theories in the early 1890s Tesla discarded the idea of using radio waves. He did not necessarily believe that radio waves existed as theorized by Maxwell, and he agreed with what most physicists were saying at the time: that radio waves would travel in a straight line in the same way that visible light travels, limiting their use for long-range communication. (Radio waves do travel in a straight line, but this was many years before the discovery that the ionosphere would reflect certain radio waves making skywave communication of shortwave frequency bands possible over long distances.) He believed that transmitting electrical signals beyond a line-of-sight distance would require the use of planet Earth as a conducting medium to overcome this limitation. By the end of 1895, he made statements to the press about the possibility that "Earth's electrical charge can be disturbed, and thereby electrical waves can be efficiently transmitted to any distance without the use of cables or wires", and that the electrical waves can be used to transmit "intelligible signals" and "motive power." On April 11, 1896, he stated that "messages might be conducted to all parts of the globe simultaneously" using electric waves "propagated through the atmosphere and even the ether beyond." In September 1897 he applied for a patent on a wireless power transmission scheme consisting of transmitting power between two tethered balloons maintained at 30,000 feet, an altitude where he thought a conductive layer should exist. Between 1895 and 1898, he constructed a large resonance transformer in his New York City laboratory called a magnifying transmitter to test his earth conduction theories. In 1899 he carried out large scale experiments at Colorado Springs, Colorado. Based on his measurements there, he concluded that the Earth was "literally alive with electrical vibrations." He noted that lightning strikes indicate that the Earth is a large conductor with waves of energy traveling around it. He constructed a large magnifying transmitter measuring fifty-one feet (16 m) in diameter which could develop a working potential estimated at 3.5 million to 4 million volts and was capable of producing electrical discharges exceeding one hundred feet (30 m) in length. With it he tested earth conduction and lit incandescent electric lamps adjacent to his lab in demonstrations of wireless power transmission.

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