Fast and accurate algorithm for scattering from large-scale 2D dielectric ocean surfaces

The paper presents a fast and accurate algorithm for the direct method-of-moment (MoM) numerical simulation of radar scattering from two-dimensional (2D) randomly finite-conducting (dielectric) ocean surfaces. The proposed algorithm consists of three major components: the multi-grid (MG) algorithm, the iterative generalized conjugate residual (GCR) method with a novel preconditioning strategy, and a variation of the spectral acceleration scheme devised by D. Torrungrueng and J.T. Johnson (see J. Electromagnetic Waves & App., vol.15, p.1337-62, 2001) featuring an alternative strong-weak region partitioning. While the strong field-source interaction is implemented as usual in the physical space in terms of matrix-vector dot product, the integral form of the weak field-source interaction region is carried out in the wavenumber space. The efficiency of the proposed two-layered algorithm facilitates scattering calculations from 2D finitely conducting surfaces with a total number of unknowns up to a few millions. Presented numerical simulations are typically performed at X-band frequencies with 7 m/s wind speed and 20/spl deg/ grazing angle.