Multi-frequency transmission/reception apparatus

摘要

The invention provides a multi-frequency transducer capable of obtaining desired directivity regardless of frequencies. Parallelepiped-shaped transducer elements ( 1 ) are used as transducer elements and a plurality of such transducer elements ( 1 ) are arranged in an array. The transducer elements ( 1 ) are caused to resonate using a resonant frequency in fundamental vibration mode and a resonant frequency in harmonic vibration mode determined by the dimensions (A, B) of a short edge ( 1 a) and a long edge ( 1 b) perpendicular to a longitudinal edge ( 1 c) of each transducer element ( 1 ) to transmit and receive at multiple frequencies. The angle of directivity (theta) of the transducer elements is controlled by the dimension (C) of the longitudinal edge which is set to a value which does not affect resonance in either the fundamental vibration mode or the harmonic vibration mode.