An improved MoM-PO hybrid method for scattering from multiple 3-D objects above the 2-D random conducting rough surface

An improved hybrid scheme combining the method of moment (MoM) and the physical optic (PO) is first presented to investigate scattering from multiple 3-D conducting objects above the electrically large conducting rough surface. First, the composite model is constructed by dividing rough surface into PO area and multiple objects into MoM area, and each object is divided into different area further. Next, the electric current in PO area is obtained through the PO approximation and the electric current in MoM area is computed by MoM. The contribution of PO area is coupled into impedance matrix of MoM. Domain distribution method is introduced, by which electric field integral equations are established on the surface of each object in MoM area and solved at the same time. Vector-matrix multiplication between the objects and the rough surface is accelerated by fast far field approximation, working by reducing the interaction between source point and observation point. What's more, adaptive integral method is used to accelerate the MoM part, by which the computing complexity is reduced from O(M-2) to O(MlogM). Compared with traditional coupling MoM-PO, this improved hybrid method proves to be much faster and has the same accuracy. Numerical examples are presented to analyze the composite scattering from multiple objects above rough surface under different conditions.