Efficient Synthesis of Ultrawideband Beam-Scanning Aperiodic Antenna Arrays Using Constraint-Reduced Iterative Convex Optimization

For synthesizing ultra-wideband (UWB) beam-scanning aperiodic antenna arrays under mutual coupling (MC) effects, the novel constraints-reduced iterative convex optimization (CRICO) method with a multi-step refined strategy is proposed. Firstly, two algorithms (CRICO-I and -II) are introduced to reduce the time cost of synthesizing UWB arrays by reasonably selecting the decreased sidelobe constraints. Specifically, the CRICO-I adaptively chooses the sidelobe region that corresponds to lobes with high peak level as the sidelobe constraint domain, and the CRICO-II selects the sidelobe region above a prescribed threshold level as the sidelobe constraint domain. Other sidelobe constraints outside the selected sidelobe constraint domain are removed. Additionally, a few refined steps are performed in which array layouts are successively optimized in each step, where the UWB array’s pattern is renewed by multiplying the array factor with currently updated element positions and the active element patterns (AEPs) obtained in the previous refined step. In such a way, the MC effect is incorporated into the synthesis process. Two examples of synthesizing UWB beam-scanning linear and planar arrays with different array sizes and beam-scanning ranges are conducted. Synthesis results validate the good efficiency and grating-lobes/sidelobes suppression performance of the proposed method for UWB beam-scanning aperiodic antenna array synthesis.