Waveguide-type s.a.w. filter using energy focusing interdigital transducers

The paper deals with a surface-acoustic-wave filter using a ¿¿v/v-waveguide and energy focusing interdigital transducers. The losses and the frequency response of the filter were analysed theoretically and were compared with experimental results performed on yZ-LiNbO3. In addition, it is shown both experimentally and theoretically how the waveguide length affects filter performances. The use of a waveguide and energy focusing transducers is effective in s.a.w. filters in which the input and output transducers can be arbitrary-overlap weighted independently, and the insertion loss is comparable to that for conventional s.a.w. filters. The results obtained in the paper are also effectively used in designing many of the practical s.a.w. devices employing waveguides.