Bulk wave radiation by group-type-unidirectional-transducers

Abstract

In the design of broadband low-loss group-type unidirectional transducers (GUDTs) the effect of bulk wave radiation must be considered. It influences the accurate design of the phasing network for the GUDT and increases the insertion loss. In addition, the zeros of the frequency response become less pronounced. The influence of the electrode structure of the GUDT on the cutoff frequency of bulk wave radiation is studied. The ratio of bulk wave radiation to surface wave radiation is calculated for a uniform interdigital transducer (IDT), as well as for an electrode structure of a GUDT on LiNbO/sub 3/-128rotYX, LiNbO/sub 3/-YZ, and quartz-STX. The effect of bulk wave radiation on the zeros of the frequency response is shown for several adjustments of the phasing network.<>