On the Calculation of Charge, Electrostatic Potential and Capacitance in Generalized Finite SAW Structures

Abstract

We present a method for the calculation of charge, electrostatic potential and capacitance for arbitrary, finite SAW-structures. Our method is applicable for one and two dimensional SAW-structures without any restrictions on the finger geometry and allocation. Analytical expressions for the charge and potential distribution are derived by using the method of moments and the relation between charge and potential spectral components. A semi-numer ical evaluation procedure with automatic error estimation has been devgloped. However, computation times are fairly small (several seconds on a medium scale computer), so that our technique is feasible for actual development-oriented SAW design. As a particular result the influence of the end-fingers of SAW transducers on the driving function for surface waves are discussed.