Wireless charging coils generate an alternating electromagnetic field?used?to inductively transfer energy to other coils positioned parallel and in close proximity.?The energy?is used to charge batteries or run?the?device receiving the energy. ?The coils may be designed as receivers, transmitters or dual purpose having single or multiple coils and multiple layers of windings. They are rated by their inductance, self resonant frequency, saturation current and Q factor at a given frequency.