Array Shading for a Broadband Constant-Directivity Transducer

摘要

This invention relates generally to acoustic transducers for underwater and ultrasonic applications and more particularly to a broadband directional transducer which provides a constant beamwidth that is independent of frequency over its bandwidth and which produces both an azimuthal pressure distribution that is independent of the distance from the transducer and a beam pattern that has no side lobes. A constant beamwidth transducer, that is, a transducer whose beam pattern is independent of frequency over a wide frequency range, is desirable for many applications in ultrasonics and underwater acoustics. Some examples of possible applications for such a transducer are: broadband echo ranging, high data rate communication, and nondestructive ultrasonic testing, medical diagnosis and materials research. Most directional acoustic transducers and arrays exhibit beam patterns which are frequency-dependent; for example, the beamwidth of a plane piston or line array decreases with increasing frequency. As a result, the spectral content of a transmitted or received signal varies with location in the beam.