A new deep-submergence broadband multiport underwater sound transducer

The back radiation from a transducer is normally isolated from the front radiation in order to avoid cancellation due to the out-of-phase nature of the back radiation. However, this isolation is difficult to achieve if the transducer is broadband and operated under significant ambient pressure encountered in deep submergence applications. The multiport transducer (U.S. Patent 5,184,332) offers a solution to this problem by using free-flooded resonance chambers on both the front and back surfaces of the transducer. It will be shown that with these chambers the acoustic pressure cancellation is avoided and the pressure now adds at frequencies between the two resonance’s (which set the bandwidth of the system). A multiport design for a coaxial set of cylinders driven by the two surfaces of a piezoelectric ring transducer will be presented. Results from finite element and circuit analysis models will be presented and shown to agree with measured results on the model fabricated by Massa Products Corporation, Hingham, MA. [Work supported in part by an SBIR through NUWC, Newport, RI.]