Broadband Electrical Matching Network for PZN-PT Single Crystal Underwater Acoustic Transducer

Broadband transducers have attracted much research attention due to their high data transmission efficiency, improved resolution, and ability to tackle multi-path propagation and shallow water reverberation. The present work proposed a new transformer – LC electrical matching network (EMN), which can significantly increase the bandwidth of an underwater transducer. Unlike the conventional impedance matching approach, the matching parameters based on impedance matching and broadband tuning are simultaneously considered in the proposed EMN. First, nonlinear regression fitting was used to approximate the impedance curve of the transducer and determine the parameters of the BVD model of the transducer. Then, in order to reduce the negative impacts of static capacitance C0 on the receiving sensitivity, a transformer was designed to adjust the phase at the parallel resonant frequency of the transducer and reduce the impedance of the transducer to the signal source. To further optimize the power factor of the transducer over a broad frequency range, a LC tuning circuit was introduced. Finite element analysis was also performed to verify the feasibility. Finally, a single-crystal transducer prototype was fabricated to verify the effectiveness of the proposed EMN. The results show that with EMN, the transducer’s transmitting voltage response is improved by 6.8 dB, the -6 dB bandwidth is enlarged by 23 kHz (about 12.5%), the receiving sensitivity decreased slightly at an acceptable range (about 2 dB), the peak insertion loss and its -6 dB fractional bandwidth are improved by 4 dB and about 14.1%, respectively, the power factor over the broadband was greater than 0.72.