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Don't think you are the only one who doesn't know all about wireless. Wireless is a very complex art and there are many things that those experienced have still to learn.
—A. Frederick Collins, The Radio Amateur's Hand Book –A Complete, Authentic and Informative Work on Wireless Telegraphy and Telephony (1922). These are the last two sentences of the book.


Alanson Sample with a wireless power transfer device, twice as efficient as Marin Soljacic's cylindrical version. Photo credit: Mauricio Freitas.
Youtube video Washington Uni. electrical engineering.

EPC eGaN® FET Application: Wireless Power Transfer


Published on Sep 20, 2012

Wireless power applications are gaining popularity in many commodity products. In this video EPC demonstrates how the superior switching capabilities of the eGaN FET make these gallium nitride power transistors an ideal alternative to the silicon MOSFET for wireless power transfer applications.

New Mexico Business Weekly

Intel, IDT team to develop wireless charging options

by Hunter Riley, NMBW Intern
Date: Wednesday, August 29, 2012
Wireless charging technology already exists with the use of platforms or docks, which use inductive coupling, utilizing coils to amplify the magnetic field that naturally moves a current through a wire. The difference with Intel and IDT’s resonance technology will be that you don’t need to have a platform or base with you to charge your device.
Retrieved by DonEMitchell 05:57, 11 December 2012 (MST) from

Wireless Power Transfer Coil Unit

TDK flat, spiral, multi-filament magnetic resonance coil. ©TDK
July 9, 2012
Development of Ultra-Thin Receiving Coil Unit for Wireless Power Transfer
Receiving coil unit employs a TDK proprietary flexible thin metal magnetic sheet, achieving an industry-leading thickness of only 0.57 mm. Development of a 0.50 mm type has also started.
TDK Corporation is proud to announce the development of a TDK wireless power transfer coil unit designed for Smartphones and other mobile devices. The receiving coil designed for integration in Smartphones and similar represents an industry-leading achievement, featuring a thickness of a mere 0.57 mm.
The development […] in fields such as magnetic materials technology and process technology, and involved the creation of a unique, extremely thin and flexible metal magnetic sheet. As a result, the coil unit not only is ultra thin and lightweight, it also is highly resistant to shock and therefore provides excellent reliability. Furthermore, in spite of its 0.57 mm profile, the coil's design minimizes the tendency towards rising resistance and achieves a power transfer efficiency that allows clearing the requirements of the WPC "Qi" standard. The low height of the unit is a key aspect for use in Smartphones. At this point, output current is on the order of 0.5 to 0.6 Amperes, but an even thinner 0.50 mm type with equal or better output current is already in development, with a view towards starting mass production in 2013.

Retrieved by DonEMitchell 17:35, 11 July 2012 (MDT) from

Scientists tweak wireless power transfer, Tesla nods happily in his grave

By Steve Dent posted May 16th 2012 11:14AM Source:

Wireless charging may be all the rage these days, but actually beaming electricity -- as sketched above by the man Tesla himself -- still has some snags. North Carolina State U researchers have found a way to possibly vanquish the biggest problem: the difficulty of exactly matching resonant frequencies to amplify current. If external factors like temperature change the tuning of a transmitter even slightly then power drops will occur, but circuitry developed by the NC State scientists would allow receivers to detect these changes and automatically re-tune themselves to match. This could make for more potent car and device charging in the future and, if they stretch the distances a bit, maybe we'll finally get the wire-free utopia Nikola dreamed up 120 years ago.

Retrieved by DonEMitchell 08:07, 20 May 2012 (MDT) from

Artificially structured metamaterials may boost wireless power transfer

March 13, 2012

Scientists calculate that a "perfect lens," a slab of artificial material engineered to focus electromagnetic fields in ways that natural materials can't, may increase the efficiency of some wireless power transfer systems.
Magnetic superlens-enchanced inductive coupling for wireless power transfer is accepted for publication in the Journal of Applied Physics.

Retrieved by DonEMitchell 16:49, 11 July 2012 (MDT) from News

Wireless power could cut cord for patients with implanted heart pumps

The experimental setup has a large transmission coil, at the right, connected to the building's electricity. At the left is the receiving coil, and near it is a smaller coil connected to a commercial heart pump sitting in a jar of fluid. Credit: University of Washington. Image linked from

July 12, 2011

Joshua Smith, a UW associate professor of computer science and electrical engineering who moved to the UW from Intel Research Seattle, has for the past six years been working on wireless power. The concept is a variation on inductive power, in which a transmitting coil sends out electromagnetic waves at a certain frequency and a receiving coil absorbs the energy and uses it to charge a battery. Electric toothbrush charging stations and cell phone charging pads use a similar system, except that in both those cases the tool has to actually touch the charger and be held in a fixed position.

Smith and colleagues at the UW and Intel devised an inductive system that adjusts the frequency and other parameters as the distance or orientation between the transmitter and receiver coils changes, allowing for flexible yet efficient wireless power over medium distances.

Retrieved by DonEMitchell 16:37, 11 July 2012 (MDT) from

Wireless power-transfer system demo

Uploaded October 2010
URL: News

Sony develops highly efficient wireless power transfer system based on magnetic resonance

October 2, 2009
Sony Corp. today announced the development of a highly efficient wireless power transfer system that eliminates the use of power cables from electronic products such as television sets. Using this system, up to 60 Watts of electrical energy can be transferred over a distance of 50cm (at an efficiency of approximately 80%, approximately 60% including rectifier). This new wireless power transfer system incorporates a form of contactless electrical energy transmission technology based on magnetic resonance. With magnetic resonance, electromagnetic energy is only transferred to recipient devices that share the identical resonant frequencies as the energy source, so energy transfer efficiency is maintained, even when misalignment occurs. Furthermore, even if there are metal objects located between the transmitter and receiver, no heat induction occurs. Sony has also drawn on its years of experience developing high radio frequency (RF) technologies for use in wireless communications and broadcast products to create a new rectifier that realizes both high speed and high efficiency. The new wireless power transfer system combines these technologies to realize a transfer efficiency of 60%, even when a rectifier is included. Sony has also developed passive extender units that are set to the same frequencies as the transmission and recipient devices, enabling the transfer distance to be extended from 50cm to 80cm (based on fundamental experiments conducted using components only) without any degradation in transfer efficiency.
Read more at: Science, Wireless

Video: WiTricity is back, promises wireless power within 18 months

By Vlad Savov, posted July 24th 2009 8:02AM

What started out as an MIT project two years ago has now progressed into a full-fledged company -- ladies and gentlemen, meet WiTricity Corp. Auntie Beeb (that's the BBC for you Yanks) has grabbed the firm's CEO Eric Giler to discuss some pretty aggressive plans for bringing wireless power to the masses. Yes, we're talking actual through-the-air wireless as opposed to something like Palm's Touchstone, which requires physical contact between charger and chargee. Based on magnetic induction, the magical technology is apparently mature enough to be deployed in the relatively near future, and if all goes to plan, "near future" could translate into "18 months from now." Also of note, Intel is hard at work developing the original concept, and if the parallel engineering of the same idea by two companies isn't enough to get your skepticism dialed down and your browser to the video past the break, what is?

Retrieved by DonEMitchell 08:07, 20 May 2012 (MDT) from

My window to the world
Mauricio Freitas Technology Reporter

Wireless Power shown at Intel Developer Forum 2008

By Mauricio Freitas, in Technology, posted: 22-Aug-2008 04:39

I am sitting through Day 3 keynotes and now it's the Research and Development keynote session with Justin Rattner. Lots of pictures to load later, but I wanted to post this one because I think it's the big thing out here: wireless power transmission.
Unlike those "wireless power" gimmicks shown at CES, which require special connectors and devices actually touch the power source, this one transmits power over the air - we are talking about 60 watts power over two feet, at 75% power efficiency.
Based on principles proposed by MIT physicists, Intel researchers have been working on a Wireless Resonant Energy Link (WREL).
WREL promises to deliver wireless power safely and efficiently. The technology relies on strongly coupled resonators. Intel says that with this technology enabled in a laptop, for example, batteries could be recharged when the laptop gets within several feet of the transmit resonator. Many engineering challenges remain, but the company's researchers hope to find a way to cut the last cord in mobile devices and someday enable wireless power in Intel-based platforms.

Retrieved by DonEMitchell 07:09, 20 May 2012 (MDT) from

IEEE Spectrum –inside tech talks
BLOGS // Tech Talk

Wireless energy

POSTED BY: Sally Adee / Thu, August 21, 2008

The New York Times reports today from the Intel Developers Forum that Intel is the latest to tantalize us with the promise of wireless power.
Wireless power! No more noodle soup under my desk where brutal Darwinian struggles unfold between the cell phone charger, the laptop charger, the digital camera charger, and the electric carving knife charger*, all jockeying for space on the power strip.
On Thursday, the chip maker plans to demonstrate the use of a magnetic field to broadcast up to 60 watts of power two to three feet. It says it can do that losing only 25 percent of the power in transmission.
Intel calls it WiTricity (wireless electricity) and it's built on the shoulders of MIT giant Marin Soljacic. Mauricio Freitas has cool pictures.

Retrieved by DonEMitchell 07:09, 20 May 2012 (MDT) from

Intel Moves to Free Gadgets of Their Recharging Cords

Published: August 20, 2008
SAN FRANCISCO — Intel has made progress in a technology that could lead to the wireless recharging of gadgets and the end of the power-cord spaghetti behind electronic devices.
It says it has increased the efficiency of a technique for wirelessly powering consumer gadgets and computers, a development that could allow a person to simply place a device on a desktop or countertop to power it. It could bring the consumer electronics industry a step closer to a world without wires.
On Thursday, the chip maker plans to demonstrate the use of a magnetic field to broadcast up to 60 watts of power two to three feet. It says it can do that losing only 25 percent of the power in transmission.
“Something like this technology could be embedded in tables and work surfaces,” said Justin Rattner, Intel’s chief technology officer, “so as soon as you put down an appropriately equipped device it would immediately begin drawing power.”
The presentation is part of the company’s Intel Developer Forum, a series of events here that the company uses to showcase new technologies in personal computing and related consumer technologies.
The research project, which is being led by Joshua R. Smith, an Intel researcher at a company laboratory in Seattle, builds on the work of the Massachusetts Institute of Technology physicist Marin Soljacic, who pioneered the idea of wirelessly transmitting power using resonant magnetic fields. The MIT group refers to the idea as WiTricity, a play on wireless and electricity. Both the M.I.T. group and the Intel researchers are exploring a phenomenon known as “resonant induction,” making it possible to transmit power several feet without wires.
Induction is already used to recharge electric toothbrushes, but that approach is limited by the need for the toothbrush to be placed in the base station.
The M.I.T. group has demonstrated efficiencies of 50 percent at ranges of several meters.
Intel is in the midst of an internal debate over whether the technology may also permit the shift to supercapacitors, which can be recharged far more quickly than today’s batteries. “In the future, your kitchen counters might do it,” Mr. Rattner said. “You’d just drop your espresso maker down on them and you would never have to plug it in.”
The Intel team describes its system as a “wireless resonant energy link,” and is experimenting with antennas less than two feet in diameter to remotely light a 60-watt light bulb.
In 2006, the M.I.T. researchers demonstrated that by sending electromagnetic waves around a waveguide it was possible to produce “evanescent” waves that could permit electricity to wirelessly tunnel to another waveguide “tuned” to the transmitting loop.
Several start-up firms , including WildCharge, based in Boulder, Colo., and WiPower, based in Altamonte Springs, Fla., have already announced related wireless charging technologies. But these demonstrations have required that the consumer gadgets touch the charging station.
The Intel researchers said they were thinking about designing a system that would make it possible to recharge a laptop computer without wires.
“From Intel’s position that seems like the thing to shoot for right now,” Mr. Smith said. The receiving antenna is about the size of something that could easily fit against the bottom of a conventional laptop computer. “It could be that cellphones and P.D.A.’s are even more compelling, but I think we are going to start with the laptop. It’s easy to dial down from laptops,” he said.
The researchers said that Intel could produce a prototype design and that it might contribute to products by developing chip sets for manufacturers. At Thursday’s research presentation, Mr. Smith plans to demonstrate an application using an electric field sensor — a natural capability of some fish — to give added dexterity to robotic arms and hands. He has designed a sensor system that makes it possible for a robot hand to gauge the size of an apple and then grasp it. The hand then carries the apple to an outstretched human hand. When it senses the hand, it drops the apple.
A version of this article appeared in print on August 21, 2008, on page C4 of the New York edition.
©New York Times, Inc.

Retrieved by DonEMitchell 08:20, 22 May 2012 (MDT) from


Misc. Gadgets, Wireless

MIT's wireless electricity demoed, dubbed WiTricity

By Ryan Block posted June 7th 2007 3:39PM

We always knew Tesla was right: MIT physics professor Marin Soljacic and his team of researchers behind the latest wireless electricity scheme have reportedly demoed their magnetically coupled resonator technology on a 60-watt lightbulb that wasn't plugged in. Of course, no technology should be without a name, and so they've dubbed it WiTricity. Apparently Soljacic thinks it's possible to commercialize WiTricity within the next few years, which would be totally amazing if it was powered by Steorn's humanity-saving infinite energy device. [Warning: subscription req'd for link]

Retrieved by DonEMitchell 10:09, 20 May 2012 (MDT) from

Goodbye wires!

MIT News Wireless power transfer over two-meter distance, from the coil on the left to the coil on the right, where it powers a 60W light bulb. Members of the team that performed the experiment are obstructing the direct line of sight between the coils; front row: Peter Fisher (left) and Robert Moffatt; second row: Marin Soljacic; third row: Andre Kurs (left), John Joannopoulos and Aristeidis Karalis. ;Photo / Aristeidis Karalis

MIT News

June 7, 2007
MIT team experimentally demonstrates wireless power transfer, potentially useful for powering laptops, cell phones without cords
Franklin Hadley, Institute for Soldier Nanotechnologies
A team from MIT's Department of Physics, Department of Electrical Engineering and Computer Science, and Institute for Soldier Nanotechnologies (ISN) has experimentally demonstrated an important step toward accomplishing this vision of the future.
The team members are Andre Kurs, Aristeidis Karalis, Robert Moffatt, Prof. Peter Fisher, and Prof. John Joannopoulos (Francis Wright Davis Chair and director of ISN), led by Prof. Marin Soljacic.
Realizing their recent theoretical prediction, they were able to light a 60W light bulb from a power source seven feet (more than two meters) away; there was no physical connection between the source and the appliance. The MIT team refers to its concept as "WiTricity" (as in wireless electricity). The work will be reported in the June 7 issue of Science Express, the advance online publication of the journal Science.


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Retrieved by DonEMitchell 23:21, 30 July 2012 (MDT) from