Fast computation of the impedance matrix for the periodic Method of Moments using a plane wave decomposition

Full-wave simulations of 2D periodic arrays using the Method of Moments (MoM) are investigated. A method based on plane wave decomposition is used to fill the MoM impedance matrix. For pair of basis and testing functions that are close to each other, a singular term is removed before extrapolating the value of the impedance matrix using a Taylor expansion. The two main advantages of this method are the easy computation of the derivative of the impedance matrix involved in the Taylor expansion and the fact that the singularity extraction can be performed once for all phase shifts between consecutive unit cells. The latter property proves to be useful when the Array Scanning Method (ASM) is to be used.