Numerical simulation of scattering from object embedded in a medium with randomly rough boundary

An FD-TD algorithm is used to compute the scattering from objects embedded in a homogeneous medium with a rough top boundary. The rough top boundary is modeled as a randomly rough surface with Gaussian correlation function and height distribution. A three dimensional randomly rough surface with specified correlation length and height standard deviation is generated on the computer. To reduce computation, the volume of grids above the rough boundary (observation region) is chosen to be small. A near-to-far field transformation is utilized to determine the far-zone scattered field due to the rough boundary and the object underneath. Possible errors near the edge of the surface are suppressed by the absorbing boundary condition and by introducing a windowing function. The far-field scattering patterns of a cylindrical-shaped object embedded in a medium with rough top boundary are generated and presented in this paper