波束扫描反射阵列天线偏焦特性

针对波束扫描反射阵列天线在大角度扫描时增益下降及方向图恶化等问题，提出通过馈源偏焦来改善反射阵列天线的扫描性能。采用方形贴片结构设计了一款工作在X频段的反射阵列天线。研究馈源在15°,30°,45°扫描角的纵向偏焦以及10°,20°和30°扫描角的横向偏焦对波束扫描反射阵列天线性能的影响。测试结果显示，在扫描角度较小时，横向偏焦引起波束指向的改变，波束宽度变化不大。减小馈源纵向偏焦尺寸，旁瓣电平减小，中心频率处的增益提高，尤其是在较大的扫描角度时效果更加明显，有利于提高波束扫描反射阵列天线的大角度扫描能力。

Defocus characteristics of beam scanning reflectarray antenna

Aiming at the problems of beam scanning reflectarray antennas such as gain reduction and pattern deterioration during large-angle scanning, a method is proposed to improve the scanning performance of the reflectarray by defocusing the feed. Without loss of generality, a reflectarray antenna that works in the X-band is designed with a square patch structure. The effects of longitudinal defocusing at 15°, 30°, and 45° scanning angles and lateral defocusing at 10°, 20°, and 30° scanning angles on the performance of beam scanning reflectarray antennas are studied. The measured results show that when the scanning angle is small, the lateral defocus causes the beam direction to change, and the beamwidth does not change much. When reducing the size of the longitudinal defocus of the feed, the sidelobe level is reduced, and the gain at the center frequency is improved. The larger the scanning angle is, the more obvious the effect becomes. This is beneficial to improve the large-angle scanning capability of the beam scanning reflective array antenna.