An accelerated DFT-MoM for the analysis of large finite periodic antenna arrays

A novel approach which utilizes a discrete Fourier transform (DFT)-based preconditioner in an iterative moment method (MoM) solution of the governing integral equation for the electromagnetic (EM) problems of the radiation and scattering from large finite periodic antenna arrays is presented. The preconditioner is primarily constructed via the block-diagonal approximation of the transformed impedance matrix in the DFT domain, in which that matrix becomes sparse and nearly diagonal due to the properties of the DFT basis functions. The preconditioner in the original spatial domain is simply obtained by the inverse DFT. This preconditioner is shown to significantly improve the convergence rate of the iterative solution. Moreover, it is rather simple to implement and requires relatively small extra computational cost. The performance of the present approach is illustrated through numerical results.