A Nested Facet Method of the Kirchhoff Approximation for Large-Scale Land Scattering

A nested facet method (NFM) of the Kirchhoff approximation (KA) is developed for land applications for signals of opportunity (SoOp) applications. This NFM follows the form of a tree data structure wherein a series of child facets are superimposed over the parent planar facet. The electric field of a parent facet is taken as the coherent sum of each child facet. The method is found to be flexible and efficient for use on consumer-grade computers, offering significant performance boosts compared to direct integration methods and is easily parallelizable. This solution to the Stratton-Chu integral can provide flexible scattering solutions in areas where analytical or statistics-based solutions may struggle to find an appropriate parameterization of the surface.