Scattering of surface acoustic waves by a system of topographical irregularities comparable to a wavelength

Scattering of surface acoustic waves (SAWs) in a reflective delay line, which is a Y+128°-cut lithium niobate substrate with aluminum interdigital transducers and reflecting structures located on its surface, is investigated by the finite-element method. The effects of scattering of SAW RF pulses by various surface irregularities are investigated in order to determine the topological parameters that minimize the loss of the SAW energy caused by the bulk-mode radiation into the substrate. The dependences of the energy coefficients of reflection and absorption of SAW RF pulses on the height and width of the reflecting irregularities whose dimensions are comparable to a wavelength have been determined.