Folded Path Microwave Acoustic Volume Wave Delay Lines.

摘要

For long time delays at frequencies above one gigahertz, volume waves have the advantage that the dominant loss mechanism, attenuation, is much lower than that of surface waves. The disadvantage of volume waves is that their faster velocity results in larger delay lines. This limitation has been circumvented by the implementation of novel folded path geometries. The first approach involves the generation of longitudinal waves with a ZnO transducer on one side of an yttrium aluminum garnet (YAG) prism, 23mm by 9mm by 4mm, and their detection on the opposite side. This delay line has a time delay of 13.5 microsec. The second approach consists of the generation of longitudinal waves in a YAG prism, their conversion to transverse waves by reflection from the sides of the prism, and their final reconversion back to longitudinal waves. The novel 28.3 microsec delay line 71mm by 9mm by 3mm, only requires the deposition of a single ZnO film. Folded delay lines are important for achieving long time delays with bandwidths in the gigahertz range. (Author)