Broadened bandwidth ultrasonic sensors via multi-resonant connection for high-accuracy discharge localization

Abstract Air-coupled ultrasonic sensors are widely used in source locating such as electrical discharge detection. However, their typical resonant structures can only respond to a narrow bandwidth stimulus and throw away information from other frequencies of ultrasonic sources deviating from its resonant frequency, leaving accuracy improvement a great challenge. Here we propose a multi-resonant structure that series connects four sensor units with successive resonant frequencies and packs together in one module. With this design, the bandwidth is broadened 2.8 times ranging from 20 kHz to 40 kHz while maintaining an average sensitivity of 45 dB. Then a sensor array composed of eight annular distributed modules is fabricated and tested by spatial locating of electrical discharge. As a result, the multi-resonant sensor array presents an accuracy of 92.5%-95% in the tested range, which is 58.82%∼ 81.82% higher than that of the single resonant sensor array. This finding provides a universal method for broadening the bandwidth for piezoelectric sensors for precise detecting and locating.