Accurate prediction of dispersion and attenuation of long metal strip SAW waveguides on anisotropic substrate

As a design tool for high-precision long broadband SAW (surface acoustic wave) delay lines, a computationally simple model for strip waveguides has been improved by inclusion of parametric fits to measured anisotropy, dispersion, and attenuation of Rayleigh wave propagation both on free and metallized surfaces of LiNbO₃. A heuristic approach was used to account for the effect of anisotropy in the case of an imaginary transverse propagation constant, and for the observed increased attenuation in waveguides compared to unbounded surfaces. The model does not rely on material properties as computed from fundamental material constants, and uses only one adjustable parameter which is not directly obtained from surface wave measurements. The phase nonlinearly can be predicted with an accuracy up to ±0.5°/μs over a relative bandwidth on the order of 50%