Electromagnetic Wave Scattering Analysis From 2-D Periodic Rough Surfaces Using Complex Images Technique

The integral equation technique, in combination with the method of moments, is widely used for treating the electromagnetic scattering from periodic rough surfaces. This method, however, requires the computation of a kernel (a periodic Green's function) that consists of a slowly converging infinite series of conventional Green's functions. To accelerate the convergence of this series, different methods have been proposed in literature. In this paper, we use a complex image (CI) technique to find a closed-form expression for the periodic Green's function, which is then used to analyze the electromagnetic scattering from arbitrary periodic rough surfaces. The resulting CI Green's function consists of a finite number of terms corresponding to real and complex sources. Moreover, the CI Green's function in the Hankel form (evanescent waves) is used if the observation and source points are close. In the far-field region, the series in the plane-wave form (propagating Floquet modes) caused by the extraction of poles are sufficient and necessary. The results indicate that the presented CI Green's function leads to numerical efficiency yet having a rather high level of accuracy.