FDTD Simulation of Very Large Domains Applied to Radar Propagation over the Ocean

A domain decomposition method for analyzing very large FDTD domains, tens of thousands of wavelengths long, is demonstrated by application to the problem of RADAR scattering in the maritime environment. Success depends on the elimination of artificial scattering from the “sky” boundary which is ensured by an ultra-high performance absorbing termination that eliminates this reflection at angles of incidence less than 0.03 degrees off grazing. The results are cross-validated against a parabolic equation (PE) method and surface integral equation method on a 1.7km sea surface problem, and to a PE method on propagation through an inhomogeneous atmosphere in a 4kmlong space, both at X-band. Further comparisons are made against boundary integral equation and PE methods from the literature in a 3.6km space containing an inhomogeneous atmosphere above a flat sea at S-band. Details of the method are given for the twodimensional problem (2D). Application to three-dimensions (3D) is demonstrated by comparing the 2D solution to the 3D solution of a sea-corridor 1.3m wide, 2.25m tall, by 110m long.