Unidirectional Underwater-Sound Pressure-Gradient Transducer

Results are presented for the design, construction, and calibration of an experimental, low‐frequency, pressure‐gradient, underwater sound transducer that utilizes a liquid‐filled, acoustic phase‐shift network to obtain a unidirectional (cardioid) directivity response over a prescribed frequency range. A solution for satisfying a number of analytical relationships, which are known to exist among certain physical parameters of the device, its environment, and the acoustic phase‐shift network, is outlined. Design specifications defining the over‐all physical configuration of the transducer, the acoustic phase‐shift network parameters, and the piezoceramic pressure‐gradient element, are given. Presentation of experimental data, in the form of azimuth directivity responses, demonstrates that a unidirectional (cardioid) response was achieved consistently between 4000 and 6000 Hz. Front‐to‐back discriminations ranging between 15 and 27 dB were recorded over the upper half of the frequency range (5000–6000 Hz), ...