Analysis of Composite Scattering from a Target Above/Below a Dielectric Rough Surface using Higher Order Basis Functions

In this paper, the validity of four types of higher order basis functions for analyzing the 3D EM scattering from the target and dielectric rough surface is investigated. Although the higher order basis functions can reduce the number of unknowns significantly, the iterative solution time may increase with the order of the basis because the matrix condition numbers deteriorates with the basis order increase. This may be relative to: (a) The truncation of the dielectric rough surface and the interaction between the object and the rough surface; (b) the properties of the basis functions adopted. In this paper, a variety of models including a rough surface only, an object above or below the rough surface are investigated with different higher order basis functions. The program is based on the Poggio-Miller-Chang-Harrington-Wu-Tsai (PMCHW) integral equations. The multilevel fast multipole algorithm (MLFMA) and flexible generalized minimal residual (FGMRES) techniques are used to further accelerate the iteration solution.