Optimal Phase-Matching Strategy for Beam Scanning of Sub-Arrayed Phased Arrays

The design of phased array antennas generating two functional beams is addressed here. The first/primary beam is fixed and it is generated at the element level (EL) through the complex (amplitude and phase) weighting coefficients, while the second/secondary one is synthesized at the subarray level by aggregating the array elements into nonoverlapped clusters and using additional phase shifters at the clusters outputs. Toward this end, the subarray configuration is determined by means of an ad hoc iterative method aimed at reducing the unavoidable quantization lobes, while the synthesis of the subarray phase coefficients; once the excitations at the EL have been set, is cast as a phase-matching problem whose analytic solution is optimal since it guarantees the minimum least-square error with respect to a reference phase distribution. A set of representative numerical results is reported and discussed to validate the proposed design approach and to point out its features and potentialities when addressing the synthesis of both pencil and shaped-beam power patterns.