Diffraction minimization in SAW devices using wide aperture compensation

A relationship is outlined between the previously derived uniform asymptotic expansion (UAE) for surface acoustic waves on anisotropic substrates and the intuitive geometrical theory of diffraction (GTD). It is demonstrated that even for an anisotropic medium, the leading terms in the UAE have a direct interpretation in terms of the simple GTD. This model allows a physical explanation of the mechanism of ;wide aperture diffraction minimization', a simple technique that allows an almost complete elimination of diffractive effects in SAW devices by merely increasing the aperture of the unapodized transducer by a calculable amount. These techniques are illustrated with both theoretical and experimental results.