Enhancing the Robustness of the Discrete Complex Image Method for Planar Multilayered Media

A simple method is described that enhances the robustness of the discrete complex image method (DCIM) for Green functions in planar multilayered media. The standard DCIM can fail in the large-p range, where p is the horizontal distance between the source and field-points - even if the guided waves are extracted prior to the complex image approximation. This can occur, in particular, when a significant lateral wave component is present. In the improved method, the spectral kernels are sampled close to the branch point, thus better capturing the lateral wave contribution to the spectrum. As a result, the applicability of the DCIM is extended to larger p values.