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

      • 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(axial-ratio, AR)波束扫描特性。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°~90°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xozyoz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AR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xozyoz平面可实现-60°~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,xozyoz平面的波束扫描AR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。所提出的方向图可重构设计方法能够大幅简化阵列复杂度,为方向图可重构天线阵列的实际应用提供了绝佳的起点。

         

        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 reconfigurability. 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. The proposed design methodology for pattern reconfigurable subarray is of significant importance, particularly due to its ability to greatly simplify the complexity of the array, providing an excellent starting point for the practical application of pattern reconfigurable antenna arrays.

         

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