Scattering from dielectric objects buried beneath random rough ground: Validating the semi-analytic mode matching algorithm with two-dimensional FDFD

A 2D finite difference frequency domain (FDFD) algorithm is used to verify new semi-analytic mode matching (SAMM) simulations of scattered fields resulting from plane waves incident on a random rough dielectric half-space containing a buried dielectric target. The SAMM algorithm uses moderately low-order modal superpositions of cylindrical waves, each of which satisfies the 2D-Helmholtz equation in its appropriate region (air, ground, or mine) and then matches all nonzero electric and magnetic field components at each interface by least squares fitting. For smooth ground, coordinate scattering centers (CSCs) are chosen at the mine center and at its image above the plane to model scattering. For random rough ground, additional CSCs are located within the rough layer. Excellent agreement between SD-FDFD and the two dimensional version of SAMM is observed, with 2D-SAMM being at least an order of magnitude faster; 3D-SAMM is estimated to be four orders of magnitude faster than SD-FDFD, with drastically reduced memory requirements