Dipole directivity patterns in simple and cost-efficient piezoelectric vector hydrophones: Modeling and testing

• A simple and low-cost piezoelectric vector hydrophone is reported. • This device uses a piezoelectric circular plate with different clamped conditions. • Simulation models and experimental results of vector hydrophones are presented. • The design of the hydrophone facilities its application in marine environments. • This hydrophone can be used to detect hydroacoustic signals in marine ecosystems. Vector hydrophones enable the acquisition of underwater acoustic signals for monitoring aquatic fauna and supporting marine ecosystem protection. However, conventional underwater acoustic technologies often involve complex structural designs, challenging component integration, high fabrication costs, and demanding signal-processing requirements, which limit their cost-effectiveness. To address these challenges, we propose a low-cost and simple vector hydrophone based on a piezoelectric diaphragm structure of commercial lead zirconate titanate (PZT) film. The hydrophone design enables the easy integration of its main components, simplifying the measurement system for underwater acoustic signals. In addition, the proposed hydrophone features a simple piezoelectric cantilever structure, enabling its use and portability in various marine scenarios. The resonance frequencies and directivity patterns of the hydrophone structure are modeled using finite element method simulations. Also, the hydrophone performance is measured within a calibration tank.. The fabricated hydrophone exhibits a resonant frequency near 8 kHz and a sensitivity of −200 dB (re 1 V/µPa), together with a well-defined figure-of-eight directivity pattern. The dipole directivity pattern of the hydrophone at resonance achieves 22 dB difference between normal and perpendicular sound incidence. Thus, the reported vector hydrophone has potential applications for underwater acoustic signal sensing in marine ecosystems, without requiring sophisticated and expensive components.