An acoustic-surface-wave multistrip coupler, formed into the shape of a U, may be used on materials of high electro-mechanical coupling coefficient to convert a bidirectional interdigital transducer into a unidirectional transducer with negligible loss of bandwidth. The U-shaped coupler by itself acts as a normal-incidence mirror, and can have a reflection loss of less than 2 dB over a 60% bandwidth. Both devices are constructed of evaporated aluminium by existing photolithographic techiques. No special polishing operations or extra electrical components are required.
No takes yet. Share an insight, caveat, or question.
Marshall et al. (1971) studied this question.