Wireless energy transfer is the transfer of electromagnetic energy for power to do work via conduction, induction, or transmission without a physical connection. Electromagnetism is the physics of the electromagnetic field: a field, encompassing all of space, which exerts a force on those particles that possess the property of electric charge, and is in turn affected by the presence and motion of such particles. ... In physics, power (symbol: P) is the amount of work done per unit of time. ... Work (abbreviated W) is defined as the line integral of a scalar product of force and displacement vectors (see below). ... Electrical conduction is the movement of electrically charged particles through matter. ... Electromagnetic induction is the production of an electrical potential difference (or voltage) across a conductor situated in a changing magnetic flux. ...

Description

Wireless energy transfer, by definition, does not require a physical medium through which to flow. Anyone can demonstrate that energy can be transmitted without a direct physical connection by simply touching the ends of a wire, briefly, to the ends of a small battery. Hold the wire near a compass needle while you do this and you'll see the compass needle twitch. It takes energy to make something move, so you've transmitted energy wirelessly. The needle moves because the electric current which briefly flows through the wire generates a magnetic field which acts on the needle (see electromagnetic induction and magnetic field for more information). Compass in a wooden box A compass (or mariners compass) is a navigational instrument for finding directions on the earth. ... Electromagnetic induction is the production of an electrical potential difference (or voltage) across a conductor situated in a changing magnetic flux. ... Current flowing through a wire produces a magnetic field (B, labeled M here) around the wire. ...

Another, more dramatic demonstration of wireless energy uses a radio transmitter generating more than a few watts, such as an amateur radio transmitter. A Fluorescent lamp with no wires attached to it, held near the antenna, will glow when the transmitter is activated. Send "SOS" and the light blinks "SOS". The transmitted energy causes the gas inside the lamp to glow, like the northern lights. A compact fluorescent lamp with an integrated electronic ballast A fluorescent lamp is a type of lamp that uses electricity to excite mercury vapor in argon or neon gas, resulting in a plasma that produces short-wave ultraviolet light. ... Northern Lights is a common name for the polar aurorae in the northern hemisphere. ...

Once the basic principle is established, then the problem is to concentrate the energy of the transmission so that most of it is received where it can be converted into useful power. Think of a flashlight that lets you focus the light beam or spread it out so that it's very wide. If you wanted to shine the flashlight on a solar cell, you'd want the flashlight's beam to be tightly focussed to reduce the amount of energy which does not fall on the receiver and is lost. Primary energy is energy contained in raw fuels and any other forms of energy received by a system as input to the system. ...

Early systems (such as Tesla proposed) were incapable of such "focusing" of transmitted energy, because the necessary antenna size is impractically large at low frequencies (see extremely low frequency radio waves). Without focusing, much of the energy would be lost to the atmosphere. Tesla can refer to: Scientist and inventor Nikola Tesla The tesla, an SI unit named after Nikola Tesla. ... Extremely low frequency (ELF) is the band of radio frequencies from 3 to 30 Hz. ... Saturns atmosphere is made up of hydorgen, helium and methane ...

The advent of technology for much higher transmission frequencies (such as those used by microwave transmitters) created the possibility of "beaming" the energy through the use of directional antennas, such as the one invented by Hidetsugu Yagi. Lasers, which create a coherent and tightly "beamed" form of light energy, are even more appropriate. Microwave image of 3C353 galaxy at 8. ... Log-periodic dipole array A directional antenna is an antenna which transmits or receives maximum power in a particular direction. ... Hidetsugu Yagi (八木 秀次 Yagi Hidetsugu, January 28, 1886 - January 19, 1976) was a Japanese electrical scientist who wrote several important articles that led to the development of the Yagi antenna, which allows directional communication with electromagnetic waves. ... For alternative meanings see laser (disambiguation). ...

In most cases the cost of such solutions is much higher than simply using copper wire. Wireless energy transfer is therefore most applicable to situations where the energy receiver cannot be copper-tethered to the energy source — such as sending energy to an airplane or spacecraft, or another planet, or in the case of solar power satellites, from orbital satellites to a rectenna on Earth. A solar power satellite, or SPS, is a proposed satellite built in high Earth orbit that uses microwave power transmission to beam solar power to a very large antenna on Earth where it can be used in place of conventional power sources. ... A rectenna is a rectifying antenna, a special type of antenna that is used to directly convert microwave energy into DC electricity. ... Earth (often referred to as The Earth) is the third planet in the solar system in terms of distance from the Sun, and the fifth in order of size. ...

History

As the wireless art developed during the turn of the 20th century, industry was looking toward a method of wireless energy transfer. At the St. Louis World's Fair (1904) a prize was offered for a successful attempt to drive an 0.1 Horsepower air-ship motor by energy transmitted through space at a distance of least 100ft. (The Electrician (London), September 1902, pages 814-815) SHP redirects here. ... Rotating magnetic field as a sum of magnetic vectors from 3 phase coils. ...

Hertz

A precursor of this technology can be found in the works of Heinrich Rudolf Hertz in the late nineteenth century. In 1888, Hertz experimented with pulsed power transmission at 500 megahertz. Heinrich Hertz Heinrich Rudolf Hertz (February 22, 1857 - January 1, 1894), was the German physicist and mechanician for whom the hertz, the SI unit, is named. ... Alternative meaning: Nineteenth Century (periodical) (18th century — 19th century — 20th century — more centuries) As a means of recording the passage of time, the 19th century was that century which lasted from 1801-1900 in the sense of the Gregorian calendar. ... 1888 (MDCCCLXXXVIII) is a leap year starting on Sunday (click on link for calendar) of the Gregorian calendar or a leap year starting on Tuesday of the Julian calendar. ...

Tesla

The development of wireless energy transfer began in earnest with the lectures and patents of the electrical engineer Nikola Tesla (and is described in his 1916 deposition on the history of wireless and radio technology). In experiments around 1899, Tesla was able to light lamps filled with gas (similar to neon) from over 25 miles away without using wires. Tesla used a high frequency current (Prodigal Genius, O'Neill; pg 193). During his experiments in Colorado, he lit ordinary incandescent lamps at 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 was at a distance of one-hundred feet from the primary circuit energized by the oscillator (Century Magazine, June 1900). This article or section is in need of attention from an expert on the subject. ... 1916 (MCMXVI) was a leap year starting on Saturday (link will take you to calendar). ... General Name, Symbol, Number neon, Ne, 10 Chemical series noble gases Group, Period, Block 18, 2, p Appearance colorless Atomic mass 20. ...

The construction of a global wireless energy distribution system centred on his Wardenclyffe Tower was started almost a century ago by Tesla but was abandoned due to a lack of investment funds. The Wardenclyffe facility was meant to be the start of a national (and later global) system of towers broadcasting power to users as electromagnetic waves. There is some evidence that Wardenclyffe might have used extremely low frequency signals combined with higher frequency signals. In practice, the transmitter electrically influences both the earth and the space above it. He made a point of describing the process as being essentially the same as passing electricity through a wire by conduction. Tesla believed that energy could be efficiently transmitted from the facility via longitudinal "non-Hertzian" (or non-Maxwellian) waves (ed. see waves in plasmas for examples). Powered by an industrial alternator, the tower was apparently intended to inject large amounts of energy into a natural Earth circuit, using the Earth-Ionosphere circuit as the transmission conduit. Tesla called his wireless technique the "disturbed charge of ground and air method." Wardenclyffe Tower located in Shoreham, Long Island, New York. ... Electromagnetic radiation can be conceptualized as a self propagating transverse oscillating wave of electric and magnetic fields. ... Extremely low frequency (ELF) is the band of radio frequencies from 3 to 30 Hz. ... Longitudinal waves, also referred to as compressional waves or pressure waves, are waves that have vibrations along or parallel to their direction of travel. ... A plasma is a quasineutral, electrically conductive fluid. ... Relationship of the atmosphere and ionosphere The ionosphere is the part of the atmosphere that is ionized by solar radiation. ...

In various writings, Tesla explained that the Earth itself would behave as a resonant LC circuit that could be electrically excited at predescribed frequencies. However, Earth resonance would be of a very low frequency (about 7 Hz) which would utilize Schumann resonance. Alternatively, a surface or ground wave, similar to the Zenneck wave could have been utilized. Others believe that earth currents were to be utilized. According to Tesla, the planet's large cross-sectional area provides a low resistance path for the flow of earth currents. The greatest losses are apt to occur at the points where the transmitting and receiving stations are connected with the ground. This is why Tesla stated, The Tacoma Narrows Bridge (shown twisting) in Washington collapsed spectacularly, under moderate wind, in part because of resonance. ... The Schumann Resonance is a set of spectrum peaks in the ELF portion of the Earths electromagnetic field spectrum. ... // In physics, a surface wave is, for a mechanical wave, guided along the interface between two differing mediums. ... A telluric current is an electric current in the Earth (both land and sea). ...

"You see the underground work is one of the most expensive parts of the tower. In this system that I have invented it is necessary for the machine to get a grip of the earth, otherwise it cannot shake the earth. It has to have a grip on the earth so that the whole of this globe can quiver, and to do that it is necessary to carry out a very expensive construction." ["Nikola Tesla On His Work With Alternating Currents and Their Application to Wireless Telegraphy, Telephony and Transmission of Power", p. 203]

To close the circuit, in theory, a second path would be established between the plants' elevated high-voltage terminals through rarefied upper-level atmospheric strata. The connection would be made by electrostatic induction or conduction through plasma. Tesla firmly believed that Wardenclyffe would permit wireless transmission and reception across large distances with negligible losses. Electrostatic induction is a method by which an electrically charged object can be used to create an electrical charge in a second object, without contact between the two objects. ... Look up plasma in Wiktionary, the free dictionary. ...

Yagi

In Japan, Hidetsugu Yagi attempted wireless power transmission. In February 1926, Yagi and Uda published their first report on the wave projector directional antenna, later known as the yagi antenna. Yagi managed to demonstrate a proof of concept, but the engineering problems proved to be more onerous than conventional systems. [1] Hidetsugu Yagi (八木 秀次 Yagi Hidetsugu, January 28, 1886 - January 19, 1976) was a Japanese electrical scientist who wrote several important articles that led to the development of the Yagi antenna, which allows directional communication with electromagnetic waves. ... 1926 (MCMXXVI) was a common year starting on Friday (link will take you to calendar). ... A Yagi-Uda antenna. ...

Uses

The wireless transfer of energy is used in various devices, such as electric toothbrushes (to recharge their batteries), the transcutaneous energy transfer (TET) systems in artificial hearts like AbioCor and most notably in mobile phones. Electric toothbrush An electric toothbrush is a toothbrush that uses electric power to move the brush head. ... An artificial heart is a device that is implanted into the body to replace the original biological heart. ... AbioCor is an artificial heart developed by the Massachusetts-based company AbioMed. ...

See also

• Distributed generation
• Electricity distribution
• Electricity market
• Electric power transmission
• HV-AC, High voltage alternating current
• Radiant energy
• Tesla effect
• Electrodynamic tethers

Distributed generation is a new trend in electric power generation. ... The examples and perspective in this article or section may not represent a worldwide view. ... Electricity markets have been and continue to be developed as a result of the deregulation of electricity utilities around the world. ... Transmission lines in Lund, Sweden Electric power transmission is one process in the delivery of electricity to consumers. ... In electrical engineering High voltage refers to a voltage which is high. ... City lights viewed in a motion blurred exposure. ... Radiant energy is the energy of electromagnetic waves. ... The Tesla effect (named in honor of Nikola Tesla) is a type of high field gradient between electrode plates for wireless energy transfer via electromagnetic induction. ... Artists conception of satellite with a tether Tether propulsion uses long, strong strings (known as tethers) to change the orbits of spacecraft. ...

Related patents

• U.S. Patent 649621, "Apparatus for Transmission of Electrical Energy".
• U.S. Patent 685953, "Apparatus for Utilizing Effects Transmitted from a Distance to a Receiving Device through Natural Media".
• U.S. Patent 685954, "Method of Utilizing Effects Transmitted through Natural Media".
• U.S. Patent 514168, "Means for Generating Electric Currents".
• U.S. Patent 593138, "Electrical Transformer".
• U.S. Patent 685955, "Apparatus for Utilizing Effects Transmitted From A Distance To A Receiving Device Through Natural Media".
• U.S. Patent 685956, "Apparatus for Utilizing Effects Transmitted through Natural Media".
• U.S. Patent 685957, "Apparatus for the Utilization of Radiant Energy".
• U.S. Patent 685958, "Method of Utilizing of Radiant Energy".
• U.S. Patent 787412, "Art of Transmitting Electrical Energy through the Natural Mediums".
• U.S. Patent 1119732 , "Apparatus for Transmitting Electrical Energy".
• U.S. Patent 1990977, "Energy transmission system".
• U.S. Patent 2415688, "Induction device".
• U.S. Patent 6798716, "System and method for wireless electrical power transmission ".
• U.S. Patent 6906495, "Contact-less power transfer".

External articles, references, and further reading

Nikola Tesla

• Margaret Cheney, "Tesla: Man Out of Time". Simon and Schuster, Oct 2, 2001. ISBN 0743215362
• Leland Anderson, ed., "Nikola Tesla On His Work With Alternating Currents And Their Application to Wireless Telegraphy, Telephony, and Transmission of Power". Twenty First Century Books, 1992. ISBN 1893817016.
• Nikola Tesla, "The True Wireless". Electrical Experimenter, May 1919
• Nikola Tesla, "The Transmission of Electric Energy Without Wires". Electrical World and Engineer, March 5, 1904.
• Toby Grotz, "Project Tesla: Wireless Transmission of Power; Resonating Planet Earth". Theoretical Electromagnetic Studies and Learning Association, Inc.
• Gary L. Peterson, "The Wireless Transmission of Electrical Energy". Feed Line No. 8.
• Nikola Tesla, "The Problem of Increasing Human Energy". Century Illustrated Magazine, June 1900.
• Nikola Tesla, "World System of Wireless Transmission of Energy"". Telegraph and Telegraph Age, October 16, 1927
• "Telsa: Life and legacy; Colorado Springs". PBS.
• "1931 Electric Pierce Arrow | Tesla FAQ No. 16". Twenty First Century Books.

Books, essays, and papers

• Thomas W. Benson, "Wireless Transmission of Power now Possible". Electrical experimenter, March 1920.
• Ahamid Aidinejad and James F. Corum, "The Transient Propagation of ELF Pulses in the Earth-Ionosphere Cavity".
• Toby Grotz, "Artificially Stimulated Resonance of the Earth's Schumann Cavity Waveguide". Proceedings of the Third International New Energy Technology Symposium/Exhibition, June 25th-28th, 1988.
• James O. McSpadden
  • "Collection of Power from Space, References".
  • "Wireless Power Transmission Demonstration".
• "Inverse Rectennas for Two-Way Wireless Power Transmission; Suitable rectennas under reverse bias can be made to act as transmitters". NASA's Jet Propulsion Laboratory, Pasadena, California.
• PlanetAnalog, "Cutting the Last Wire, True wireless devices require untethered power distribution". 13 December 2005.
• "Radiant Energy -- Wireless Transformer of High Power Lines?". PES Network, Inc., 2005.

Other history

• Frank E. Little, James O. McSpadden, Kai Chang, and Nobuyuki Kaya, "Toward space solar power: Wireless energy transmission experiments past, present and future". AIP Conference Proceedings, January 15, 1998, Volume 420, Issue 1, pp. 1225-1233.
• Lewis Coe, "Wireless Radio: A History". McFarland & Company, Jul 1, 1996. ISBN 0786402598
• W. C. Brown,
  • "The history of wireless power transmission". Solar Energy, Vol. 56, No. 1, pp. 3-21, 1996.
  • "The History of Power Transmission by Radio Waves". IEEE Transactions on Microwave Theory and Techniques, 1984.

Toby Grotz is an electrical engineer. ... PBS re-directs here; for alternate uses see PBS (disambiguation) PBS logo The Public Broadcasting Service (PBS) is a non-profit public broadcasting television service with 349 member TV stations in the United States. ...

External links

• Project Tesla
• History of Microwave Power Transmission before 1980
• The SHARP's DC-to-DC power transmission system