Scattering analysis of SAW asymmetrical resonators and delay lines

Analytical expressions for the transfer function and reflection coefficients of the surface acoustic wave (SAW) two-port asymmetrical resonator were obtained using the scattering matrix method. This resonator consists of two different interdigital transducers (IDTs) and reflectors located asymmetrically with respect to the centre of the resonator structure. Equations for the normalised amplitudes for forward and backward travelling SAWs in areas between the IDTs and reflectors have been written and solved. Numerical calculations of the above functions are possible by using the analytical expressions for the admittances and the scattering coefficients of the IDTs and the reflection coefficients of the reflectors. The analytical expressions obtained for the two-port asymmetrical resonator can also be used for the analysis and design of asymmetrical one-port resonators and delay lines.