Probability model of the multipath delays in radar echoes of scatters above 3-D surfaces

In the radar imaging of the object above three-dimensional (3-D) ocean surface, the multipath scattering brings in artifacts which can be reckoned as the distorted and shifted replicas of the direct-path scatters. As it is the propagation delays that play an important role in the understanding of these artifacts, this paper proposes a probability model of the multipath delays for the scatters above the 3-D ocean surface. As the premise, the surface is endowed with the Kirchhoff approximation, as well as a probability density function of the elevations and slopes. The probability model is then deduced and is validated by the electromagnetic computation results. In addition, the influence of relevant parameters is analyzed using the Monte Carlo techniques.