Abstract: There are two main factors limiting the wide-angle scanning capability of planar phased array antennas, viz., insufficient radiation projection of array elements in high-elevation regions and impedance mismatch occurring at large scan angles. The former can be addressed by designing wide-beam radiating elements, while the latter is difficult to eliminate and leads to rapid gain degradation or even scan blindness. To address this issue, a wide-angle impedance matching structure design method based on pixelated periodic structures is proposed to improve impedance mismatch during large-angle scanning and broaden the active impedance matching bandwidth of phased arrays. Specifically, two pixelated structures were implemented and compared for their wide-angle impedance matching performance using the internal multi-port method and non-dominated sorting genetic algorithm, based on negative electromagnetic parameter products and surface wave suppression mechanisms respectively. Both one-dimensional (1-D) and two-dimensional (2-D) wide-angle scanning phased array antenna design cases and corresponding simulation and experimental results are presented to validate the conclusions. The designed pixel matching layer is ultimately proven effective for improving active beam scanning performance in both 1-D and 2-D scanning, such as optimizing impedance matching or reducing gain fluctuations of scanned beams.