CASCADING FORMULAS FOR IDENTICAL TRANSDUCER P-MATRICES

Formulas are derived for the P-matrix of a cascade of identical acoust ic transducers, in terms of the P-matrix of one elementary transducer. The derivation makes no assumptions other than reciprocity and the va lidity of the P-matrix description. Consequently, the results are vali d for a wide range of cases, such as simple SAW gratings or group-type single-phase unidirectional transducers (SPUDT's), where each element is a transducer pills grating. The formulas are used to derive a gene ral relation for the directivity of a SPUDT in terms of the directivit y of one period.