Surface wave to bulk wave conversion in SAW reflectors on strong coupling substrates

Abstract

Reflective structures consisting of arrays of single or interconnected metallic strips exhibit surface to bulk wave conversion at frequencies above a certain threshold frequency. The resulting attenuation of the reflected SAW-signal due to bulk wave losses is of concern, if either very low loss (VLL) filters have to be built, or if a well defined, potentially small amount of reflectivity is desired. In contrast to traditional simulation methods for reflectors, we employ a self-consistent approach based on the Green's function formalism. Its main advantage is the fact that the finite extent of the grating as well as surface wave-bulk wave interaction are both taken into account accurately. We discuss the bulk wave conversion properties of open, shorted and mixed (so called open-shorted) finite reflectors made of strips in strictly periodic or chirped arrangement, and the design of bulk wave conversion gratings