The evaluation of the input admittance of SAW interdigital transducers

Abstract

Using the moment‐method technique, the exact charge distribution on a finite interdigital array is obtained. Full account is taken of the coupling to bulk and surface modes. The moment‐method technique greatly simplifies the evaluation of the transducer input admittance. The frequency dependence of the input admittance is computed for a different number of electrode pairs, different metallization ratio, and different sequences. The electrostatic capacitance is proved to be 28% higher than the zero‐coupling capacitance for Y‐Z lithium niobate.