Equivalent four-port networks using force factors for SAW interdigital transducers

We have derived the equivalent four-port network of an N-pair of interdigital transducers (IDTs) using force factors. Since this four-port network is distinct enough in physical meaning and is of a concise structure, the equivalent network of the whole of the system of the SAW device can also be composed very easily with good visibility. On the other hand, we have derived the transfer matrix of this four-port network. Since the individual elements of the transfer matrix of the N-pair of an IDT are expressed in closed forms, the analysis of the performance of a SAW filter with a multi-electrode structure such as the interdigited interdigital transducer (IIDT) can be made with high efficiency