Design and realization of directivity adjustable ring transducer

In this paper, a directional segmented ring transmitting transducer, which can radiate sound waves in any horizontal region, has been developed. First, we introduce the structure of the segmented ring transducer and the characteristics of its radiation sound field, investigate the transmitting beam pattern control method based on the modal synthesis, and propose orthogonal beam pattern functions to adjust steering angles. Then, the threedimensional finite element model of the segmented ring transducer is established, and the amplitude and phase of sound pressure excited by the first three modes, respectively, are calculated as a function of the frequency. We can combine each mode to obtain the desired beam patterns, and simulate the transmitting beam patterns steering to different directions. Finally, we manufacture the segmented ring transducer and measure its transmitting directivity in an anechoic water tank, and the first three modes are also calibrated according to the measured sound pressure. The experimental results show that the beam pattern synthesized by the first two modes has a 3 dB down beam width of about 156 at 15 kHz after calibration, and the maximum source level is approximately 24 dB higher than the minimum. The -3 dB beam width synthesized by the first three modes is about 84 at 17 kHz after calibration. In addition, we also carry out the experimental test on the proposed beam control method, and the driving-voltage weighting vectors are designed to obtain good transmitting beam patterns steering to different angles.