Numerical simulation of omnidirectional scattering from three-dimensional randomly rough dielectric surfaces

Three-dimensional randomly rough surface patches with a Gaussian correlation function and height distribution are generated on the computer. An FDTD algorithm with scattered field formulation is used to compute scattering from surface patches by numerically solving Maxwell´s equations for the scattered field using a central difference approximation for the space and time derivatives. To reduce computation, the volume of grids above the rough surface is chosen to be small. A transformation is used to convert the scattered fields into far zone fields for bistatic scattering coefficient calculations. Possible errors near the edge of the surface due to the use of a relatively small volume are suppressed by introducing a windowing function. The omnidirectional scattering patterns of the rough surfaces are generated for each incident direction. Good agreements are obtained between the results obtained by this method and those calculated by an Integral Equation Method (IEM) for bistatic scattering from randomly rough surfaces