Self-consistent analysis of arbitrary 1D SAW transducers

We describe a self-consistent calculational method for the analysis of SAW transducers with arbitrary finger widths, such as EWC and DART SPUDTs. A Green´s function consisting of an electrostatic and a SAW-generating component is used to model the substrate; bulk-wave radiation and mass-loading effects are neglected. The geometry for the transducer is defined in terms of the electrical boundary conditions. The charge distribution on the electrodes is approximated via the well-known (1-x²)^-½-weighted Chebyshev polynomials. Only few degrees of freedom per electrode are needed to reach fair precision. For improved convergence, the method of moments is applied, yielding a system of linear equations to be solved for the coefficients of the charge distribution. The charge distribution is computed and the complete frequency-dependent P-matrix is extracted for arbitrary geometries. We present results for several uniform and SPUDT-type SAW-devices