Efficient scattering analysis of PEC objects above halfspace over wide angular and frequency band

Abstract

In this paper, an efficient numerical approach is proposed for analyzing the scattering from PEC objects above a lossy half space over wide angular and frequency band. One of the principal tools for the analysis of scattering from targets located in half-space is the method of moments (MoM) and the half-space multilevel fast multipole algorithm (MLFMA). Since the surface current and the scattered field are functions of the incidence angle and frequency, it will cost lots of time for analysis of monostatic scattering over a wide frequency band. To reduce the computation time, an efficient numerical approach is proposed in this paper. The mixed potential integral equation (MPIE) for a general PEC object located above a lossy half space is first presented by using half space Green's functions. Then, the half-space MLFMA is utilized for the efficient matrix multiplication. An adaptive cross approximation (ACA) based method is used for fast analysis of the scattered field with multiple incident angles. Compared with solving linear equations at each angle repeatedly, the ACA method is able to greatly reduce the computation time. The geometric theory of diffraction (GTD) model based interpolation method is utilized for fast analysis of the scattered field over wide frequency band. By utilizing the GTD model parameters, the scattered field over a wide frequency band can be calculated approximately by MoM solutions at very fewer frequency sampling points. This means that plenty of time can be saved comparing with modeling at each frequency sampling points. Numerical examples are presented and analyzed to demonstrate the valid and efficiency of the proposed approach.