Theory for SAW Grooved Reflector Arrays

The reflection and bulk-wave loss characteristics of a SAW grooved reflector array are treated using an approach which integrates field theory with the theory of two-mode coupling well-known in the area of optical gratings. The present treatment offers the following distinct advantages over the previously reported equivalent network approach: i) it derives the array characteristics directly in terms of the material constants of the substrate; ii) it provides quantitative information on the power loss resulting from bulk-wave radiation; and iii) it can readily and accurately accommodate changes in groove profile or height among the individual array elements, making this approach amenable for use in the design of tapered arrays. Computed SAW scattering characteristics of a uniform reflector array comprised of a varying number of trapezoidal (but almost rectangular) grooves are presented.