The Hybrid EPILE + PO Combined with the Adaptive Cross Approximation to Study the Electromagnetic Scattering from two 3D Scatterers

Calculating the RCS (Radar Cross Section) of two 3D scatterers (target above a rough surface) needs to numerically solve a set of integral equations involving a large number of unknowns. Such large applications in remote sensing cannot be solved easily with a conventional Method of Moments (MoM) by using a direct LU inversion. Thus, hybridization between the E-PILE (Extended Propagation-Inside-Layer Expansion) and the Physical Optics approximation (PO) reduces significantly the memory requirements and CPU time. The resulting method called E-PILE + PO. In this work, we take advantage of the rank-deficient nature of the coupling matrices, corresponding to scatterer 1 and scatterer 2 interactions, to further reduce the complexity of the method by using the ACA (Adaptive Cross Approximation). The ACA algorithm permits to strongly compress the coupling matrices without a loss of accuracy and the memory requirement is then strongly reduced. The proposed method is then applied for a scenario of a square plate located above sea-like two-dimensional rough surface.