激发涡旋电磁波的同相位馈电圆形天线阵设计

现有的线极化天线单元组成的圆形天线阵要激发涡旋电磁波,需对天线阵进行等相位差馈电,馈电网络结构较复杂。文中首先从理论上探讨利用圆极化天线单元组成的圆形天线阵产生涡旋电磁波的可能性,基于圆极化波传播特性,通过旋转圆极化天线单元而使相邻天线单元的远区辐射场产生相位差,导出圆形天线阵远场区的电磁辐射公式,论证圆极化的圆形天线阵在同相位馈电时能产生涡旋电磁波束。进而,以8 个天线单元构成的圆形天线阵为例进行仿真验证。结果表明,通过合理的天线单元角度分布替代移相器模块功能,只需使用相同相位的馈电端口就能产生l =0,±1,±2,±3 七种模式的轨道角动量,这种新型轨道角动量激发技术有效提升了馈电网络设计的灵活性。

Design of Circularly Polarized Circular Antenna Array with In-phase Feeder for Vortex Electromagnetic Wave

The vortex electromagnetic wave is usually generated by the circular antenna array composed of linearly polarized cells. And the feeder network becomes complex by the equiphase offset feeder. This paper theoretically demonstrates the possibility of vortex electromagnetic wave generated by the circular antenna array with circularly polarized cells. Based on the propagation characteristics of the circularly polarized wave, the electromagnetic radiation in the far field of the circular antenna array is calculated under the phase shift between the adjacent cells, by whirling the circularly polarized cells. Results prove that the vortex electromagnetic wave can be generated by the circularly polarized circular antenna array under the same phase. The simulated results also show that seven modes of orbital angular momentum, which marked as l =0, ±1, ±2,±3, can be generated by the feeder port with the same phase and adjusting the distribution degree of cells. The flexibility of feeder network could be effectively improved through this novel excitation technology of orbital angular momentum.