The Hybrid EPILE plus 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.