PURPOSE: To provide a sensor, with reliability and high accuracy, which contains a power supply/signal receiver physically separated from a signal generator.

CONSTITUTION: Power supply/signal receivers 58A-58D are provided with a solenoid coil, which generates a varying magnetic field, and a radiation detector, which receives modulated beam and generates an output signal modulated as a function of the beam. Signal generators 56A-56D comprise a relay coil, which is assigned in the varying magnetic field generated by the solenoid coil, a transducer circuit, which is connected to the relay coil to generate a modulated transducer signal generated with a detected parameter and supplied with power from the power supply/signal receiver, and a radiation source, which is connected to the transducer circuit to generate the modulated radiation beam and supplied with power from the power supply/signal receiver.