Design and fabrication of a multimode ring vector hydrophone

Typical underwater acoustic sensors can measure the magnitude of an incoming sound wave but cannot identify the direction. In this paper, a new simple method for detecting the direction of a sound wave with a piezoelectric ring hydrophone is proposed. This method divides the piezoceramic ring of the hydrophone into eight elements and distinguishes the direction of the sound wave by combining the output voltages of the elements in a particular manner. The validity of the design method was confirmed through the fabrication of an experimental prototype of the ring hydrophone with the proposed structure and a comparison of its performance with the design results. The method allows the ring vector hydrophone to operate over a very wide frequency range without being restricted to its structural resonant frequencies.