FAST ALL MODES (FAM) METHOD COMBINED WITH NMSP FOR EVALUATING SPATIAL DOMAIN LAYERED MEDIUM GREEN'S FUNCTIONS OF MODERATE THICKNESS

摘要

An efficient and novel approach, the fast all modes (FAM) method, was developed to locate all modes precisely on the entire complex plane for a single layered media. The modes include surface wave modes, leaky wave modes, and improper modes. For the case where the layer thickness is 1 wavelength, the pre-processing FAM requires 0.34 s for computing 500 mode locations of both TE and TM modes using a Pentium IV 3.2 GHz PC running Matlab. To justify our FAM method, we use the numerical modified steepest-descent path (NMSP) method to evaluate spatial domain Green's functions for mixed potentials GA and GV. The NMSP method computes the steepest descent integral with all the pole proximities extracted and replaced by incomplete error functions. The CPU per distance point based on the FAM/NMSP method takes less than 6 mss for all distance ranges. All computed results are accurate to within 0.2% of the conventional half space extraction method.