Apodization of multilayer bulk-wave transducers

Recent experiments have demonstrated the use of superlattice transducers for bulk acoustic waves in the gigahertz frequency range. The transducers consisted of multilayers of ZnO or LiNbO/sub 3/ with alternating crystal orientations or polarizations. A procedure for calculating the electromechanical characteristics of general multilayer transducers in which the individual layers are anisotropic and piezoelectric and have arbitrary crystal orientation is described. The algorithm used is numerically stable and easily implemented for use on a personal computer using commercial software. A network model is also derived to provide both an approximate analysis of multilayer transducer performance and an insight into synthesis procedures. Examples are used to compare the two approaches and illustrate an initial design procedure for broadband transducers.<>