An improved wireless transmission system for transferring power over a distance. The system includes a transmitter generating a magnetic field and a receiver for inducing a voltage in response to the magnetic field. In various respects, the receiver is configured to be implanted in a body. The receiver may include a housing enclosing a receiving coil and associated electronic components, a covering around at least a portion of the housing, and at least two wires wrapped around the housing to form a plurality of turns. The covering may be formed of a ferrite material configured to both magnetically shield a respective portion of the internal volume of the housing and redirect incoming magnetic flux from the transmitter to improve efficiency. Methods of use are also provided.