基于超表面单元的高性能2D波束扫描圆极化方向图可重构天线阵列
High-Performance 2D Beam Scanning Circularly Polarized Pattern Reconfigurable Antenna Array Based on Metasurface Element
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摘要: 本文提出了一种新型的高性能2D方向图可重构圆极化天线阵列，其具备宽角度与角域宽轴比波束扫描特性。宽轴比是指在宽角度扫描范围下轴比低于3 dB。该设计通过在圆极化天线B的对角位置引入一个1比特圆极化超表面天线A，实现了2D方向图可重构功能。1比特天线A加载了两个PIN二极管以实现0°与180°之间的相位切换。由于结构差异，天线A与B之间存在90°的相位差。因此，通过控制天线A，可使A与B之间的相位差在90°至-90°之间切换，相应辐射方向图随之在P模式与N模式间转换。基于天线A与B的对角布置方式，在xoz与yoz平面同时引入了相位差，从而实现了2D方向图可重构。所设计的2D方向图可重构圆极化天线仅需两个PIN二极管，结构简洁且成本低廉。此外，通过在地板刻蚀缝隙，有效增强了单元的轴比特性。将提出的2D方向图可重构圆极化天线组成4×4阵列后，该阵列在xoz和yoz平面可实现-60°至60°的扫描范围，增益变化为2.58 dBi，副瓣电平优于7.94 dB。在±60°扫描范围内，xoz和yoz平面的波束扫描轴比均在3 dB左右。最后加工制作了4×4方向图可重构圆极化天线阵列进行验证，测试结果与仿真结果吻合良好。Abstract: This paper presents a novel 2D pattern reconfigurable circularly polarized antenna, which features wide-angle and angle domain wide axial-ratio (AR) scanning characteristics. Wide AR means that the AR is less than 3 dB in the wide angle scanning range. By introducing a 1-bit circularly polarized antenna A at the diagonal position of circularly polarized antenna B, the 2D pattern reconfigurable circularly polarized antenna can be achieved. The 1-bit antenna A is loaded with two PIN diodes to achieve phase switching between 0° and 180°. Due to the structural difference, there is a 90° phase difference between antenna A and B. Consequently, by controlling antenna A, the phase difference between antenna A and B is switched from 90° to -90°. The corresponding radiation pattern is switched from P-mode to N-mode. Owing to the diagonal placement of antennas A and B, a phase difference is introduced in both the xoz and yoz planes, thereby enabling the 2D pattern reconfigurablility. The designed 2D pattern reconfigurable circularly polarized antenna only requires two PIN diodes, making it a simple and low-cost design. Moreover, by etching slots on the ground plane, the AR characteristics of the unit cell are enhanced. The proposed 2D pattern reconfigurable circularly polarized antenna is arranged into a 4×4 array. The array has a scanning range of -60° to 60° in the xoz and yoz planes, with a gain variation of 2.58 dBi and a sidelobe level greater than 7.94 dB. An AR of less than 3 dB is achieved for beam scanning in the xoz and yoz planes from -60° to 60°. A 4×4 pattern reconfigurable circularly polarized antenna array is fabricated for verification. The measured results are in good agreement with the simulation results.
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