Ultra-wideband underwater acoustic transducer with a gradient impedance matching layer

In complex marine environments, high-efficiency, wideband and high-frequency transducers can improve the imaging resolution of sonar systems and there is an urgent need for the detection and identification of seafloor landforms. The bandwidth expansion of the traditional transducer is usually achieved by using a single or multiple uniformly matching layers, but it cannot meet the ultra-wideband performance requirement of the transducer in water because it fails to achieve an optimal acoustic impedance transition. Based on theoretical analysis of sound transmission, analytical calculation, and finite element simulation, an acoustic gradient impedance matching layer transducer is studied. We propose an acoustic gradient impedance matching layer material that largely compensates for this shortcoming. This gradient matching layer material has the characteristic that the acoustic impedance decreases in the direction of thickness according to an exponential law z(x)=z1e2αx. It is implemented by filling the specific binary mixture into the conical cavities structure produced by 3D accurately printing. Experimental testing results show that the transducer's transmitting voltage response bandwidth (−3dB) reaches 110%.