Abstract: A numerical finite-difference time-domain(FDTD) approach for electromagnetic scattering from a dielectric target over randomly rough surface is developed in a three dimensional model.The rough surface is truncated in the simulation by using periodic surface extension.One period of rough surface is related to the surface correlation length.Generation of incident waves upon a rough surface is presented.Numerical model of a target on/above a rough surface is designed.Polarized bistatic scattering from the target and rough surface is obtained based on numerical distribution of near fields.A comparison of three-dimensional and conventional two-dimensional models is made.It shows that the back scattering from a rough surface is significantly enhanced due to the target on/above the rough surface.

Key words: 3-D target/rough surface, bistatic scattering, FDTD, periodic boundary condition