Alternative tonpilz and bender transducer designs

Abstract

Tonpilz transducer designs with half-wavelength water-sized radiating-pistons are commonly used in SONAR arrays. And here the tonpilz piston normally radiates in the broadside direction with reduced output as the array is steered to the end-fire direction. Bender transducer designs, used in low frequency applications, can take the form of a dipole transducer which, as a result of partial self-cancellation, can lead to a low source level output. We present two alternative transducer designs, which solve these problems. In the case of the tonpilz array, a cylindrical-shaped leveraged-transducer design with one-half water wavelength size and modal performance is proposed. This transducer is shown to operate in the first three modes allowing the formation of an element beam that may be steered in the general directions the array is steered, with full output in a single end-fire direction. In the case of the dipole transducer, advantage is taken of the strong near-field dipole acoustic pressure which is used to energize a nearby compliant parasitic resonator yielding a dominant monopole source of greater output. [Work supported in part by ONR.]