Fast Multilevel Physical Optics Algorithm for Far- and Near-Field Scattering Analysis of Very Large Targets

A fast algorithm based on the physical optics approximation for the evaluation of backscattered field from large scatterers in the near- and far-fields, over a range of aspect angles, frequencies, and radii is presented. The fast computational scheme employs a hierarchical decomposition of the scatterer into sub-domains, direct calculation of the scattered field on very sparse grids for the smallest domains, and multilevel phase/amplitude compensation-interpolation and aggregation scheme applied to increasingly dense grids for the evaluation of the total scattered field.