Abstract
Numerical analysis of truncated periodic structures by utilizing conventional method of moments (MoM) technique is challenging because the number of unknowns involved is often very large; hence, the computational cost is high. This letter presents a novel approach, based on the dipole moment (DM) method, for analyzing electromagnetic scattering from truncated periodic structures whose geometrical and/or material properties vary locally from those of a strictly doubly infinite periodic structure. The main advantage of using the DM method is that it provides convenient closed-form expressions for the scattered fields, facilitating the matrix computation in the context of the MoM much more efficiently than when the conventional Rao-Wilton-Glisson (RWG) type of basis functions are used for the same computation. Numerical results obtained by using the proposed approach are compared with those derived from a commercial MoM software package, and good agreement is found. The time advantage is clearly evident from this comparison.