The semi-analytic mode matching (SAMM) algorithm for efficient computation of scattered near fields from 3D dielectric targets buried in lossy soil

The 3D semi-analytic mode matching (SAMM) algorithm is used to determine the nearfield scattering from spherical, prolate spheroidal and oblate spheroidal targets buried in lossy soil. Scattering is described by moderately low-order superpositions of spherical modes originating at user-specified coordinate scattering centers (CSCs); the mode coefficients are found numerically by least-squares fitting all boundary conditions at discrete points along the relevant interfaces. Spherical buried target scattering is modeled with CSCs located at the sphere center and its image in air; with the latter modeling reflections from the underside of the plane back towards the target. For prolate spheroids, additional CSCs along the major axis of the target are necessary, while for oblate spheroids, the additional CSCs lie in the equatorial plane of the target. For a favorable choice of CSCs and a careful selection of fitting points, the SAMM algorithm converges with increasing mode number.