Design of phase shifters for a group type unidirectional transducer based on interaction analysis

A group-type unidirectional transducer (GUT) is useful for a low-loss surface acoustic wave (SAW) filter. The multiport network expressions for the GUT are presented, and interaction between the inphase and quadrature electrodes is studied analytically. The conditions for perfect unidirectivity are described. The design procedures of the phase shifters realizing perfect unidirectivity are shown both in series and parallel configurations for any geometrical phase except pi .<>