Development of air-sound transducer pairs based on a lightweight acoustic matching layer structure

To overcome uneven stress distribution, limited transmission efficiency, and beam divergence commonly associated with potting in planar air-coupled transducers, a lightweight air-to-air acoustic transceiver incorporating a cavity-structured acoustic matching layer was developed. The operating behavior of the piezoelectric ceramic was analyzed first, and an electromechanical equivalent model was established based on the radial vibration mode of thin piezoelectric discs. Finite-element simulations were then performed to model the transducer and evaluate its vibration characteristics, harmonic response, and acoustic field distribution. The influence of matching-layer thickness was examined in detail, allowing appropriate structural dimensions and material parameters to be determined and providing a theoretical basis for subsequent experiments. During experimentation, the cavity-structured matching layer was fabricated, with measured acoustic impedance and acoustic attenuation coefficient of 0.1082 MRayl and 0.247 dB/mm, respectively. Experimental results show that the proposed cavity-structured transducer achieves a 2.06-fold increase in absolute bandwidth compared with planar designs, along with an approximately 1.5-fold improvement in received signal amplitude, a 25 dB reduction in two-way insertion loss (IL), and a measured directivity opening angle of 14°. These results indicate that the transducer with the proposed matching-layer configuration has strong potential for efficient, portable, and cost-effective air-coupled ultrasonic applications.