US Patent 7906960 Inductive position sensor

A position sensor having a transmitter coil with both an outer loop portion and an inner loop portion. A receiver coil is disposed in close proximity to the transmitter coil and the receiver coil includes a first loop and an oppositely wound second loop. The receiver coil generates an electrical output signal when the transmitter coil is excited due to the inductive coupling between the transmitter and receiver coils. A movable coupler element varies the inductive coupling between the transmitter coil and the loops of the receiver coil as a function of the position of the coupler element.