Integral-Equation Analysis of Scattering From Doubly Periodic Array of 3-D Conducting Objects

The integral-equation (IE) method formulated in the spatial domain is employed to calculate the scattering from the doubly periodic array of three-dimensional (3-D) perfect electric conductor (PEC) objects. The special testing and basis functions are proposed to handle the problem with non-zero normal components of currents at the boundary of one period. Moreover, a relationship between the scattering from the PEC screen and its complementary structure is established. In order to efficiently compute the matrix elements from the IE approach, an acceleration technique with the exponential convergence rate is applied to evaluate the doubly periodic Green´s function. The formulations in this technique are appropriately modified so that the new form facilitates numerical calculation for the general cases.