An air-coupled piezoelectric transducer with a hollow polymer microsphere filled epoxy resin matching layer

A thickness mode air-coupled piezoelectric transducer is manufactured based on an equivalent circuit theoretical model,concerning both the influence of acoustic impedance and attenuation coefficient.Hollow polymer microsphere filled epoxy resin is chosen as the acoustic matching material.Impedance matching circuit and parameter optimization design is given.The central frequency is 51 kHz,-6 dB relative bandwidth is 25.4% and the two-way insertion loss is-27 dB.The result indicates that the new transducer with a low attenuation coefficient closed-pore single matching layer design not only ensures a high sensitivity but also simplifies the structure of the transducer,bringing a new solution for the air-coupled piezoelectric transducer design.