A Fast and Accurate Rational Fitting Model for Sommerfeld Integrals in Multilayered Planar Medium

This paper presents a fast evaluation technique for the spatial domain Green’s function in multilayered planar media via rational fitting. Different from the previous approaches first fitting the spectral domain Green’s function, the proposed method performs the fitting procedure purely in the spatial domain, hence the fitting accuracy is controllable. To minimize the number of samples evaluated by time-consuming numerical integration, an adaptive fitting procedure is designed. The superior performance of the proposed method compared with the conventional closed-form approximation method is verified through numerical studies.