Focal Plane Array-Fed Shaped-Beam Transmitarray With Small-Gain Ripple and Low Sidelobe Level

A novel shaped-beam transmitarray antenna fed by a focal plane array is proposed. It features small gain ripple and low sidelobe level. Unlike the traditional shaped-beam transmitarray designed by phase-only optimization, the proposed one is put forward based on the superposition principle. An array is used as the feed. When the feed elements are excited, orthogonal beams pointing at different angles are generated. Then the expected beam can be shaped by adding up these orthogonal beams with appropriate weights. Specifically, the selection criteria for the number, the angles, and the weights of these orthogonal beams are provided. Several squared-flattop beams and a flattop-cosecant squared beam are designed for validation.