A Dipole-Moment-Based Formulation for Numerically Efficient Analysis of Scattering From Truncated Periodic Structures

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.