An end-capped lead zirconate titanate broadband hydrophone theoretical calculation and electroacoustic measurement for towed array applications

Abstract

Hydrophone transducers for towed array applications require low self-noise, small form factor and a linear frequency response below 50 kHz for general purpose long-range ocean sensing. The design specification for this hydrophone application has several aspects including acoustic sensitivity, frequency response, dissipation factor, and physical size. A comprehensive noise model informs filter design for pre-amplifiers after the piezoelectric element. Theoretical calculation of pressure to voltage conversion is made here by estimating the Free-Field Voltage Sensitivity (FFVS) using methods from R.A. Langevin and G.W. McMahon. Using these methods to achieve the desired design specification, we use two cylindrical ceramics with a split electrode poled in the radial direction with series stacked ceramics using end caps with air backing to increase sensitivity and reduce overall size. An experiment is carried out to measure the resonant modes using a simple impedance measuring circuit which then can be used to estimate FFVS linearity. These results are compared with theoretical calculation for hydrophone response of resonant modes and results from measurement circuit.