Full-wave analysis of a large rectangular array of slots

Large, finite arrays are often studied in hypothesis of infinite structure, thus allowing the reduction of the numerical effort to that of a single periodic cell. Sometimes this approximation leads to reasonable results in predicting the input impedance of elements far out from the edges. However, for near edge elements it is visibly wrong. Furthermore, when wide beam angle scanning occurs, the effects of truncation can be relevant also for elements very far from the edges. A truncated Floquet waves (TFW) method has been presented, for predicting the distributions of the radiating currents, including those belonging to the edge elements of the array, while retaining a number of unknowns which is comparable with that occurring for the infinite array problem. This approach is based on the method of moments (MoM) solution of an integral equation in which the unknown function can be interpreted as due to the edge diffracted field excited by the Floquet waves of the infinite structure. In this paper, the formulation of the TFW method is applied to the 3D case of rectangular array of slots in an infinite ground-plane.