Patent attributes
A system for wirelessly charging, via a medium, a device having a receiver coil comprises at least one relay configured to inductively transfer power to the receiver coil of the device and a transmitter configured to inductively transmit, to the at least one relay, power for charging the device. A joint resonance frequencies of a transmitter resonance circuit and a relay resonance circuit have a main resonance frequency (MRF). The transmitter is configured to operate at an operational frequency (OPF) from a range of OPFs. The range of OPFs is different than the MRF. The at least one relay comprises a second relay coil connected in series to the first relay coil. One side of the second relay coil faces the device and a second side of the second relay coil is covered by a relay ferrite layer. The second relay coil is smaller than the first relay coil.