witricity

[Sankaralingam Srirajabalaguru]

Introduction of witricity:
The ability to provide electrical energy to remote objects without wires using oscillating magnetic fields.
The term WiTricity was used for a project that took place at MIT, led by Prof. Marin Soljačić in 2007
WiTricity is based on strong coupling between electromagnetic resonant objects to transfer energy wirelessly between them. This differs from other methods like simple induction, microwaves, or air ionization.
The system consists of transmitters and receivers that contain magnetic loop antennas critically tuned to the same frequency

Due to operating in the electromagnetic near field, the receiving devices must be no more than about a quarter wavelength from the transmitter (which is a few meters at the frequency used by the example system). In their first paper, the group also simulated GHz dielectric resonators. The WiTricity devices are coupled almost entirely with magnetic fields (the electric fields are largely confined within capacitors inside the devices), which is argued to make them safer than resonant energy transfer using electric fields (most famously in Tesla coils, whose high electric fields allow them to be used as lightning generators), since most materials couple weakly to magnetic fields (Kurs, 2007)