A large part of the geometry of array antennas is often partially defined by finite translational symmetries. Applying the method of moments (MoM) with the Rao–Wilton–Glisson (RWG)-like element on an appropriately structured mesh to these arrays results in an impedance matrix where the main part exhibits a multilevel block Toeplitz structure. This article introduces a memory-efficient construction method that effectively represents and reuses impedance calculations. The proposed method, applicable to electrically connected elements, also accounts for all nonsymmetric parts of the array. The core idea involves nine distinct electrically connectable components from which the array can be assembled. The derived multilevel block Toeplitz matrix is further utilized by an in-house inverse solver to achieve faster and more memory-efficient MoM current vector calculations. We demonstrate the method by computing the far-field of a 32×32 array and the scattering parameters of two tightly coupled 9×9 arrays. This approach reduces the memory allocation from O(N2xN2y) to O(NxNy) , for an Nx×Ny array.