|
|
| (One intermediate revision by one other user not shown) |
| Line 1: |
Line 1: |
| '''Resonant inductive coupling''' or '''electrodynamic induction''' is the [[Near and far field|near field]] [[wireless energy transfer|wireless transmission of electrical energy]] between two coils that are tuned to [[Electrical resonance|resonate]] at the same frequency. The equipment to do this is sometimes called a '''resonant''' or '''resonance transformer'''. While many transformers employ resonance, this type has a high [[Q factor#Electrical systems|''Q'']] and is often air cored to avoid 'iron' losses. The two coils may exist as a single piece of equipment or comprise two separate pieces of equipment.
| | These custom rubber bracelets are... <br><br>Custom plastic bracelets have been labeled as short-live fashion by most of the people. But these people have been proven by these custom silicone bracelets otherwise. These custom silicone bracelets were loved by the Lance Armstrong foundation and took the entire world by storm. They alone have sold more than 40 million bracelets worldwide! Imaging just how many that"s! That"s already about 6 per cent of the total population of just america. <br><br>These custom rubber bracelets are now the hottest development in promoting your cause, business o-r promoting your products and services. Now, you could have these rubber bracelets developed for your own function and for all occasions. They"re very tailor-made in the message, to the colors, to the fonts you"ll be using. You definintely will soon be standing out of the audience with these customized silicon bracelets. <br><br>Therefore, you are wondering the easiest way to whats of promoting your foundation. These custom rubber silicon bracelets of course. For extra information, please consider taking a gander at: [https://www.youtube.com/watch?v=CKxIYgo6iXs vibrating penis ring]. These custom silicone bracelets are highly personalized, and most of all they are inexpensive. That"s why bulk orders are no longer unique to large companies only. Today, even small organizations can purchase as many as 10,000 custom plastic bracelets or as low as 50 bracelets using their own design. <br><br>Custom silicone bracelets are a good way to promote your message to the general public since these custom silicone bracelets are very elegant and eye-catching. You will get the peoples interest easily by carrying or selling one of these simple. That"s why if you use these for fundraising, you dont have to fear because you know that your information will certainly be seen. <br><br>In summary, if you genuinely wish to promote your cause but dont have sufficient funds, then perhaps these custom plastic bracelets are the right promotional medium for you. So you may get the general publics attention quickly these custom silicone bracelets are highly personalized, inexpensive and decorative.. To explore additional info, please take a gander at: [https://www.youtube.com/watch?v=sRaqch238m4 magic massager]. Dig up new info on [https://www.youtube.com/watch?v=sRaqch238m4 best wand massager] by going to our lovely article directory.<br><br>If you have any thoughts relating to wherever and how to use [https://Rebelmouse.com/stereotypedglut12 health insurance company], you can make contact with us at the web-page. |
| | |
| Resonant transfer works by making a coil ''[[ringing (signal)|ring]]'' with an oscillating current. This generates an oscillating magnetic field. Because the coil is highly resonant, any energy placed in the coil dies away relatively slowly over very many cycles; but if a second coil is brought near it, the coil can pick up most of the energy before it is lost, even if it is some distance away. The fields used are predominately non-radiative, near field (sometimes called [[evanescent wave]]s), as all hardware is kept well within the 1/4 wavelength distance they radiate little energy from the transmitter to infinity.
| |
| | |
| One of the applications of the resonant transformer is for the [[CCFL inverter]]. Another application of the resonant transformer is to couple between stages of a [[superheterodyne receiver]], where the selectivity of the receiver is provided by tuned transformers in the intermediate-frequency amplifiers.<ref>{{cite book
| |
| | last = Carr
| |
| | first = Joseph
| |
| | title = Secrets of RF Circuit Design
| |
| | pages = 193–195
| |
| | isbn = 0-07-137067-6}}</ref> Resonant [[transformer]]s such as the [[Tesla coil]] can generate very high voltages with or without arcing, and are able to provide much higher current than electrostatic high-voltage generation machines such as the [[Van de Graaff generator]].<ref>{{cite book
| |
| | author = Abdel-Salam, M. ''et al.''
| |
| | title = High-Voltage Engineering: Theory and Practice
| |
| |pages=523–524
| |
| |isbn = 0-8247-4152-8}}</ref> Resonant energy transfer is the operating principle behind proposed short range wireless electricity systems such as [[WiTricity]] and systems that have already been deployed, such as passive [[RFID tag]]s and [[contactless smart card]]s.
| |
| | |
| ==Resonant coupling==
| |
| [[File:Resonantpowertransfer.svg|thumb|350px|Basic transmitter and receiver circuits, Rs and Rr are the resistances and losses in the associated capacitors and inductors. Ls and Lr are coupled by small coupling coefficient, k, usually below 0.2]]
| |
| Non-resonant [[coupled inductors]], such as typical [[transformer]]s, work on the principle of a [[primary coil]] generating a [[magnetic field]] and a secondary coil subtending as much as possible of that field so that the power passing through the secondary is as close as possible to that of the primary. This requirement that the field be covered by the secondary results in very short range and usually requires a [[magnetic core]]. Over greater distances the non-resonant induction method is highly inefficient and wastes the vast majority of the energy in resistive losses of the primary coil.
| |
| | |
| Using resonance can help improve efficiency dramatically. If resonant coupling is used, each coil is capacitively loaded so as to form a tuned [[LC circuit]]. If the primary and secondary coils are resonant at a common frequency, it turns out that significant power may be transmitted between the coils over a range of a few times the coil diameters at reasonable efficiency.<ref>{{cite book|url=http://books.google.com/?id=Q_ltAAAAMAAJ&dq=%22Elementary+Lectures+on+Electric+Discharges,+Waves,+and+Impulses%22&printsec=frontcover |author=Steinmetz, Dr. Charles Proteus |title=Elementary Lectures on Electric Discharges, Waves, and Impulses, and Other Transients |edition=2nd|publisher=McGraw-Hill |year=1914}}</ref>
| |
| | |
| ===Coupling coefficient===
| |
| The coupling coefficient is the fraction of the flux of the primary that cuts the secondary coil, and is a function of the geometry of the system. The coupling coefficient, k, is between 0 and 1.
| |
| | |
| Systems are said to be tightly coupled, loosely coupled, critically coupled or overcoupled. Tight coupling is when the coupling coefficient is around 1 as with conventional iron-core transformers. Overcoupling is when the secondary coil is so close that it tends to collapse the primary's field, and critical coupling is when the transfer in the passband is optimal. Loose coupling is when the coils are distant from each other, so that most of the flux misses the secondary, in Tesla coils around 0.2 is used, and at greater distances, for example for inductive wireless power transmission, it may be lower than 0.01.
| |
| | |
| ===Energy transfer and efficiency===
| |
| The general principle is that if a given oscillating amount of energy (for example a pulse or a series of pulses) is placed into a primary coil which is capacitively loaded, the coil will 'ring', and form an oscillating magnetic field. The energy will transfer back and forth between the magnetic field in the inductor and the electric field across the capacitor at the resonant frequency. This oscillation will die away at a rate determined by the gain-bandwidth ([[Q factor|''Q'' factor]]), mainly due to resistive and radiative losses. However, provided the secondary coil cuts enough of the field that it absorbs more energy than is lost in each cycle of the primary, then most of the energy can still be transferred.
| |
| | |
| The primary coil forms a series [[RLC circuit]], and the ''Q'' factor for such a coil is:
| |
| | |
| :<math>
| |
| Q = \frac{1}{R} \sqrt{\frac{L}{C}} \,
| |
| </math>,
| |
| For R=10 ohm,C=1 micro farad and L=10 mH, Q is given as 10.
| |
| | |
| Because the ''Q'' factor can be very high, (experimentally around a thousand has been demonstrated<ref name=stronglycoupled>[http://www.sciencemag.org/cgi/content/abstract/1143254 Wireless Power Transfer via Strongly Coupled Magnetic Resonances André Kurs, Aristeidis Karalis, Robert Moffatt, J. D. Joannopoulos, Peter Fisher, Marin Soljacic]</ref> with air [[magnetic core|cored]] coils) only a small percentage of the field has to be coupled from one coil to the other to achieve high efficiency, even though the field dies quickly with distance from a coil, the primary and secondary can be several diameters apart.
| |
| | |
| It can be shown that a figure of merit for the efficiency is:<ref name="WitrityWhitePaper">[http://www.witricity.com/pdfs/highly-resonant-power-transfer-kesler-witricity-2013.pdf WiTricity White Paper- Highly Resonant Wireless Power Transfer: Safe, Efficient, and Over Distance- Highly Resonant Wireless Power Transfer: Safe, Efficient, and Over Distance 2013 Morris Kesler]</ref>
| |
| | |
| :<math>U = k \sqrt{Q_1 Q_2}</math>
| |
| | |
| Where Q<sub>1</sub> and Q<sub>2</sub> is the Q factor of the source and receiver coils.
| |
| | |
| And the maximum achievable efficiency is:<ref name="WitrityWhitePaper"/>
| |
| | |
| :<math>\eta_{opt} = \frac {U^2} {(1 + \sqrt{1 + U^2}) ^ 2}</math>
| |
| | |
| ===Power transfer===
| |
| Because the ''Q'' can be very high, even when low power is fed into the transmitter coil, a relatively intense field builds up over multiple cycles, which increases the power that can be received—at resonance far more power is in the oscillating field than is being fed into the coil, and the receiver coil receives a percentage of that.
| |
| | |
| ===Voltage gain===
| |
| The voltage gain of resonantly coupled coils is directly proportional to the square root of the ratio of secondary and primary inductances.
| |
| | |
| ===Transmitter coils and circuitry===
| |
| | |
| Unlike the multiple-layer secondary of a non-resonant transformer, coils for this purpose are often single layer [[solenoids]] (to minimise [[skin effect]] and give improved ''Q'') in parallel with a suitable [[capacitor]], or they may be other shapes such as wave-wound litz wire. Insulation is either absent, with spacers, or low [[permittivity]], low loss materials such as [[silk]] to minimise dielectric losses.
| |
| | |
| [[File:Cc colp2.svg|thumb|right|Colpitts oscillator. In resonant energy transfer the inductor would be the transmitter coil and capacitors are used to tune the circuit to a suitable frequency.]]
| |
| To progressively feed energy/power into the primary coil with each cycle, different circuits can be used. One circuit employs a [[Colpitts oscillator]].<ref name=stronglycoupled/>
| |
| | |
| In Tesla coils an intermittent switching system, a "circuit controller" or "break," is used to inject an impulsive signal into the primary coil; the secondary coil then rings and decays.
| |
| | |
| ===Receiver coils and circuitry===
| |
| [[File:RF-Smartcard.svg|thumb|right|The receiver of a smart card has a coil connected to a chip which provides capacitance to give resonance as well as regulators to provide a suitable voltage]]
| |
| The secondary receiver coils are similar designs to the primary sending coils. Running the secondary at the same resonant frequency as the primary ensures that the secondary has a low [[impedance (electrical)|impedance]] at the transmitter's frequency and that the energy is optimally absorbed.
| |
| [[File:Resonant inductive coupling experiment conducted by CT&T Laboratories, december 2012, 13 inch transmission distance.jpg|thumb|Example receiver coil. The coil is loaded with a capacitor and two LEDs. The coil and the capacitor form a series LC circuit which is tuned to a resonant frequency that matches the transmission coil located inside of the brown matt. Power is transmitted over a distance of thirteen inches.]]
| |
| To remove energy from the secondary coil, different methods can be used, the AC can be used directly or [[rectifier|rectified]] and a regulator circuit can be used to generate DC voltage.
| |
| | |
| ==History==
| |
| [[File:Original Tesla Coil.png|thumb|left|This advanced [[Magnifying Transmitter|Tesla coil]] was designed to implement [[Wireless energy transmission#Electrical conduction|wireless power]] by means of the ''disturbed charge of ground and air method.'']]
| |
| In 1894 [[Nikola Tesla]] used resonant inductive coupling, also known as "electro-dynamic induction" to wirelessly light up phosphorescent and incandescent lamps at the 35 South Fifth Avenue laboratory, and later at the 46 E. Houston Street laboratory in New York City.<ref name="INVENTIONS, RESEARCHES AND WRITINGS OF NIKOLA TESLA-1">{{cite web|url=http://www.tfcbooks.com/tesla/1891-05-20.htm |title=Experiments with Alternating Currents of Very High Frequency and Their Application to Methods of Artificial Illumination, AIEE, Columbia College, N.Y., May 20, 1891 |date=1891-06-20}}</ref><ref name="INVENTIONS, RESEARCHES AND WRITINGS OF NIKOLA TESLA-2">{{cite web|url=http://www.tfcbooks.com/tesla/1892-02-03.htm |title=Experiments with Alternate Currents of High Potential and High Frequency, IEE Address,' London, February 1892 |date=1892-02-00}}</ref><ref name="INVENTIONS, RESEARCHES AND WRITINGS OF NIKOLA TESLA-3">{{cite web|url=http://www.tfcbooks.com/tesla/1893-02-24.htm |title=On Light and Other High Frequency Phenomena, 'Franklin Institute,' Philadelphia, February 1893, and National Electric Light Association, St. Louis, March 1893 |date=1893-03-00}}</ref> In 1897 he patented a device<ref>{{US patent|593138}} Electrical Transformer</ref> called the high-voltage, resonance [[transformer]] or "[[Tesla coil]]." Transferring electrical energy from the primary coil to the secondary coil by resonant induction, a Tesla coil is capable of producing [[High voltage|very high voltages]] at [[high frequency]]. The improved design allowed for the safe production and utilization of high-potential electrical currents, "without serious liability of the destruction of the apparatus itself and danger to persons approaching or handling it."
| |
| | |
| In the early 1960s resonant inductive wireless energy transfer was used successfully in implantable medical devices<ref>J. C. Schuder, “Powering an artificial heart: Birth of the inductively coupled-radio frequency system in 1960,” Artificial Organs, vol. 26, no. 11, pp. 909–915, 2002.</ref> including such devices as pacemakers and artificial hearts. While the early systems used a resonant receiver coil, later systems<ref>SCHWAN M. A. and P.R. Troyk, "High efficiency driver for transcutaneously coupled coils" IEEE Engineering in Medicine & Biology Society 11th Annual International Conference, November 1989, pp. 1403-1404.</ref> implemented resonant transmitter coils as well. These medical devices are designed for high efficiency using low power electronics while efficiently accommodating some misalignment and dynamic twisting of the coils. The separation between the coils in implantable applications is commonly less than 20 cm. Today resonant inductive energy transfer is regularly used for providing electric power in many commercially available medical implantable devices.<ref>{{cite web|url=http://www.cochlearamericas.com/Products/11.asp |title=What is a cochlear implant? |publisher=Cochlearamericas.com |date=2009-01-30 |accessdate=2009-06-04}}</ref>
| |
| | |
| Wireless electric energy transfer for experimentally powering electric automobiles and buses is a higher power application (>10 kW) of resonant inductive energy transfer. High power levels are required for rapid recharging and high energy transfer efficiency is required both for operational economy and to avoid negative environmental impact of the system. An experimental electrified roadway test track built circa 1990 achieved 80% energy efficiency while recharging the battery of a prototype bus at a specially equipped bus stop.<ref>Systems Control Technology, Inc, "Roadway Powered Electric Vehicle Project, Track Construction and Testing Program". UC Berkeley Path Program Technical Report: UCB-ITS-PRR-94-07, http://www.path.berkeley.edu/PATH/Publications/PDF/PRR/94/PRR-94-07.pdf</ref><ref>Shladover, S.E., “PATH at 20: History and Major Milestones”, Intelligent Transportation Systems Conference, 2006. ITSC '06. IEEE 2006, pages 1_22-1_29.</ref> The bus could be outfitted with a retractable receiving coil for greater coil clearance when moving. The gap between the transmit and receive coils was designed to be less than 10 cm when powered. In addition to buses the use of wireless transfer has been investigated for recharging electric automobiles in parking spots and garages as well.
| |
| | |
| Some of these wireless resonant inductive devices operate at low milliwatt power levels and are battery powered. Others operate at higher kilowatt power levels. Current implantable medical and road electrification device designs achieve more than 75% transfer efficiency at an operating distance between the transmit and receive coils of less than 10 cm.
| |
| | |
| In 1995, Professor John Boys and Prof Grant Covic, of [[The University of Auckland]] in New Zealand, developed systems to transfer large amounts of energy across small air gaps. {{Citation needed|date=November 2009}}
| |
| | |
| In 1998, RFID tags were patented that were powered in this way.<ref>[http://ww1.microchip.com/downloads/en/appnotes/00678b.pdf RFID Coil Design]</ref>
| |
| | |
| In November 2006, [[Marin Soljačić]] and other researchers at the [[Massachusetts Institute of Technology]] applied this near field behavior, well known in electromagnetic theory, the wireless power transmission concept based on strongly-coupled resonators.<ref name="MIT theory news">{{cite web | url = http://web.mit.edu/newsoffice/2006/wireless.html | title = Wireless electricity could power consumer, industrial electronics | publisher = [[MIT]] News | date = 2006-11-14}}</ref><ref name="MIT Physics World 1">{{cite web | url = http://physicsworld.com/cws/article/news/26422 | title = Gadget recharging goes wireless | publisher = Physics World | date = 2006-11-14}}</ref><ref name="MIT NewScientist 2006">{{cite web | url = http://www.newscientisttech.com/article/dn10575-evanescent-coupling-could-power-gadgets-wirelessly.html | title = 'Evanescent coupling' could power gadgets wirelessly | publisher = NewScientist.com news service | date = 2006-11-15}}</ref> In a theoretical analysis,<ref> | |
| {{cite journal | author = Aristeidis Karalis | coauthors = J.D. Joannopoulos, Marin Soljačić | title = Efficient wireless non-radiative mid-range energy transfer | journal = Annals of Physics | doi = 10.1016/j.aop.2007.04.017 | year = 2008 | volume = 323 | pages = 34–48 | quote = Published online: April 2007 | bibcode=2008AnPhy.323...34K|arxiv = physics/0611063 }}</ref> they demonstrate that, by designing electromagnetic resonators that suffer minimal loss due to radiation and absorption and have a near field with mid-range extent (namely a few times the resonator size), mid-range efficient wireless energy-transfer is possible. The reason is that, if two such [[resonant circuit]]s tuned to the same frequency are within a fraction of a wavelength, their near fields (consisting of '[[evanescent wave]]s') couple by means of [[evanescent wave coupling]]. Oscillating waves develop between the inductors, which can allow the energy to transfer from one object to the other within times much shorter than all loss times, which were designed to be long, and thus with the maximum possible energy-transfer efficiency. Since the resonant wavelength is much larger than the resonators, the field can circumvent extraneous objects in the vicinity and thus this mid-range energy-transfer scheme does not require line-of-sight. By utilizing in particular the magnetic field to achieve the coupling, this method can be safe, since magnetic fields interact weakly with living organisms.
| |
| | |
| [[Apple Inc.]] applied for a patent on the technology in 2010, after WiPower did so in 2008.<ref>[http://www.theregister.co.uk/2012/12/03/apple_charging_patent/ "Ready for ANOTHER patent war? Apple 'invents' wireless charging."]</ref>
| |
| | |
| ==Comparison with other technologies==
| |
| Compared to inductive transfer in conventional transformers, except when the coils are well within a diameter of each other, the efficiency is somewhat lower (around 80% at short range) whereas tightly coupled conventional transformers may achieve greater efficiency (around 90-95%) and for this reason it cannot be used where high energy transfer is required at greater distances.
| |
| | |
| However, compared to the costs associated with batteries, particularly non-rechargeable batteries, the costs of the batteries are hundreds of times higher. In situations where a source of power is available nearby, it can be a cheaper solution.<ref>{{cite web|url=http://www.ted.com/talks/eric_giler_demos_wireless_electricity.html |title=Eric Giler demos wireless electricity |accessdate=2009-09-13 |date=July 2009 |publisher=[[TED (conference)|TED]]}}</ref> In addition, whereas batteries need periodic maintenance and replacement, resonant energy transfer can be used instead. Batteries additionally generate pollution during their construction and their disposal which is largely avoided.
| |
| | |
| ==Regulations and safety==
| |
| Unlike mains-wired equipment, no direct electrical connection is needed and hence equipment can be sealed to minimize the possibility of electric shock.
| |
| | |
| Because the coupling is achieved using predominantly magnetic fields; the technology may be relatively safe. Safety standards and guidelines do exist in most countries for electromagnetic field exposures (e.g.<ref>http://www.icnirp.de/documents/emfgdl.pdf
| |
| ICNIRP Guidelines Guidelines for Limiting Exposure to Time-Varying ...</ref><ref>IEEE C95.1</ref>) Whether the system can meet the guidelines or the less stringent legal requirements depends on the delivered power and range from the transmitter.
| |
| | |
| Deployed systems already generate magnetic fields, for example [[induction cooker]]s and [[contactless smart card]] readers.
| |
| | |
| ==Uses==
| |
| *[[Contactless smart card]]
| |
| *High voltage (one million volt) sources for X-ray production<ref>[http://books.google.com/books?id=KQwAAAAAMBAJ&lpg=PA20&dq=%22resonant%20transformer%22&pg=PA20#v=onepage&q=%22resonant%20transformer%22&f=false]</ref>
| |
| *[[Tesla coil]]s
| |
| * Some Passports
| |
| | |
| ==See also==
| |
| {{div col|2}}
| |
| *[[eCoupled]] for particular implementations of this technology.
| |
| *[[Evanescent wave coupling]] essentially the same process at optical frequencies
| |
| *[[Inductance]]
| |
| *[[Microwave power transmission]] an alternative, much longer range way of transferring energy
| |
| *[[rfid|RFID]] some passive id tags are powered by radio frequency transmissions
| |
| *[[Ubeam]]<ref>[http://www.wirelesspowerplanet.com/news/young-entrepreneur-has-a-better-idea-now-what/#more-1907 Ubeam]</ref>
| |
| *[[Wardenclyffe tower]]
| |
| *[[Wireless Resonant Energy Link]] (WREL)
| |
| *[[WiTricity]]
| |
| {{div col end}}
| |
| | |
| ==References==
| |
| {{reflist}}
| |
| | |
| ==External links==
| |
| *[http://www.greencarreports.com/news/1087816_nyc-manhole-covers-to-hide-resonance-chargers-for-electric-cars NYC Manhole covers hide resonance chargers]
| |
| *[http://spectrum.ieee.org/green-tech/mass-transit/a-critical-look-at-wireless-power/0 IEEE Spectrum: A critical look at wireless power]
| |
| *[http://www.intel.com/pressroom/archive/releases/20080821comp.htm Intel: Cutting the Last Cord, Wireless Power]
| |
| *[http://news.yahoo.com/s/afp/20080821/ts_afp/usitinternetenergychipcompanyintel Yahoo News: Intel cuts electric cords with wireless power system]
| |
| *[http://news.bbc.co.uk/2/hi/technology/7575618.stm BBC News: An end to spaghetti power cables]
| |
| *[http://www.instructables.com/id/Wireless-Power-Transmission-Over-Short-Distances-U/ Instructables: wireless power]
| |
| *{{cite news | url = http://www.mit.edu/%7Esoljacic/wireless_power.html | title = Marin Soljačić (researcher team leader) home page on MIT}}
| |
| *{{cite news | url = http://news.bbc.co.uk/2/hi/technology/6725955.stm | title = Wireless energy promise powers up | author = Jonathan Fildes | publisher = [[BBC]] News | date = 2007-06-07}}
| |
| *{{cite news | url = http://www.sciam.com/article.cfm?articleid=07511C52-E7F2-99DF-3FA6ED2D7DC9AA20&chanId=sa025 | title = Wireless Energy Lights Bulb from Seven Feet Away | author = JR Minkel | publisher = [[Scientific American]] | date = 2007-06-07}}
| |
| *{{cite news | url = http://www.breitbart.com/article.php?id=paWirelessThur19Wirelesspower&show_article=1&catnum=0 | title = Breakthrough to a wireless (electricity) future (WiTricity) | publisher = The Press Association | date = 2007-06-07}}
| |
| *{{cite news | url = http://www.technewsworld.com/story/57757.html | title = MIT Wizards Zap Electricity Through the Air | author = Katherine Noyes | publisher = TechNewsWorld | date = 2007-06-08}}
| |
| *{{cite news | url = http://www.dailytech.com/MIT+Engineers+Unveil+Wireless+Power+System/article7632.htm | title = MIT Engineers Unveil Wireless Power System | author = Chris Peredun, Kristopher Kubicki | publisher = DailyTech | date = 2007-06-11}}
| |
| *{{cite news | url = http://www.sciencemag.org/cgi/data/1143254/DC1/1 | title = Supporting Online Material for Wireless Power Transfer via Strongly Coupled Magnetic Resonances | publisher = Science Magazine }}
| |
| *{{cite news | url = http://www.tfcbooks.com/articles/witricity.htm | title = Anticipating Witricity | author = Gary Peterson | publisher = 21st Century Books | date = 2008-08-06}}
| |
| * [http://www.mtt.org/awards/WCB's%20distinguished%20career.htm William C. Brown biography on the IEEE MTT-S website]
| |
| *{{cite news | url = http://thefutureofthings.com/news/5763/intel-s-wireless-power-technology-demonstrated.html | title = Intel’s Wireless Power Technology Demonstrated | author = Anuradha Menon | publisher = [[The Future of Things]] e-magazine| date = 2008-11-14}}
| |
| | |
| [[Category:Wireless energy transfer]]
| |
| [[Category:Transformers (electrical)]]
| |