<P> 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 . In a theoretical analysis, 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 circuits tuned to the same frequency are within a fraction of a wavelength, their near fields (consisting of' evanescent waves') 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 . </P> <P> Apple Inc. applied for a patent on the technology in 2010, after WiPower did so in 2008 . </P> <P> In the past, the power source used on the JR Tokai SCMaglev car was generating with a gas turbine generator . In 2011, they succeeded in powering while driving (CWD: charge while driving) across a large gap by the JR Tokai proprietary 9.8 kHz phase synchronization technology developed based on technology similar to AGV's wireless power scheme . And the Japanese Ministry of Land, Infrastructure and Transportation evaluated the technology as all the problems for practical use were cleared . Construction of SCMaglev begin and commercial use will start in 2027 . </P> <P> Non-resonant coupled inductors, such as typical transformers, 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 . </P>

Highly resonant wireless power transfer safe efficient and over distance