Piezoelectric rubber transducer : Part 3 One-dimensional constant beamwidth transducers.

Abstract

Most transducers and arrays show directional beam patterns which are frequency dependent. In this paper, transducers with a constant beamwidth in one-dimensional plane over a wide frequency range are studied both theoretically and experimentally. Some test transducers, curved rectangular and curved Hamming types with various values of curvature, are constructed from a flexible piezoelectric rubber sheet. It is shown that the rectangular type maintains a fairly constant beamwidth but the pattern is not desirable because of the appearance of large ripples in the main lobe, while the Hamming type has no ripples and the directivity is almost constant at all frequencies above a cut-off frequency.