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

A domain decomposition method for analyzing very large finite-difference time domains, tens of thousands of wavelengths long, is demonstrated by the 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 a surface integral equation method on a 1.7 km sea surface problem, and to a PE method on propagation through an inhomogeneous atmosphere in a 4 km-long space, both at X-band. Further comparisons are made against boundary integral equation and PE methods from the literature in a 3.6 km space containing an inhomogeneous atmosphere above a flat sea at S-band. Details of the method are given for the 2-D problem. Application to 3-D is demonstrated by comparing the 2-D solution with the 3-D solution of a sea corridor 1.3 m wide, 2.25 m tall, by 110 m long.