Influence of the quarter wave matching layers on the response of bar transducers

Matching layers are widely used today for large area transducers and medical arrays. Geometrical and mechanical characteristics of these layers are usually chosen with the help of the 1D design formalism. However, it doesn't take into account of lateral waves propagation in the layer which could damage radiation pattern of the transducer. The Finite Element Model, with the help of the ATILA code, permits to take this kind of phenomenon into account. In this paper, the influence of mechanical and geometrical characteristics of the matching layer on appearance of lateral modes is examined. This study is concluded by the definition of a choice criterium guaranteeing no lateral mode in the bandwidth of the transducer.