Linear motion sensor using the Doppler effect with magnetostatic waves

Abstract

Observation of the Doppler shift of magnetostatic waves and a new linear velocity and position sensor based on this effect are reported. The sensor consists of a magnetostatic surface-wave delay line in which one transducer is allowed to move along the direction of propagation. Position and velocity are indicated by the phase and Doppler shift of the transmitted signal, respectively. These effects are much larger than would be observed with ordinary electromagnetic waves at the same frequency owing to the shorter wavelengths of magnetostatic waves.