A contactless electromagnetic sensor (1) for determining a radial position of a rotor comprises a transducer (100) that comprises one or more coils. Excitation circuitry is connected to the transducer to energize the transducer. Processing circuitry derives at least one position signal indicative of a radial position of the rotor based on the transducer signals. In order to enable simplified compensation for disturbance signals resulting from target imperfections, the coils have a sensitivity to a target material that varies sinusoidally along the circumferential direction. |