Computation Of Slowness And Effective Permittivity Curves For Standard Saw Crystals

Abstract

The subject of this study is the development of software to provide for the computation of the slowness and effective permittivity functions for standard Surface Acoustic Wave (SAW) crystals. These two functions are very important in characterizing the physical properties of a substrate and their determination provides a foundation from which all further SAW device modelling can be undertaken. To achieve the goal, general wave propagation characteristics in the presence of boundaries are examined with particular emphasis on the case for piezoelectric crystals. The slowness and effective permittivity functions are presented only for the common SAW substrates supporting pure Rayleigh wave propagation. To affirm the validity of the software, the computed functions are compared with already published experimental data. Other parameters derived from the permittivity function are also compared to published results providing further justification for the validity of the software.