Wei Wen Yue, Shi Yan, Wu Quan Wei, Meng Zan Kui, Liu Zhi Qi
Opt Express. 2021 Feb 1;29(3):3754-3763. doi: 10.1364/OE.414163.
In this paper, a composite planar spiral antenna consisting of an eight-arm equiangular spiral antenna and eight Archimedean spiral antennas has been designed to radiate electromagnetic wave carrying tunable angular momenta in a wide band. A tunable eight-way Wilkinson power divider network is used to offer three kinds of feeding modes for the equiangular spiral antenna, and thus the composite antenna can radiate the electromagnetic waves with angular momenta of the modes l=1, 2, and 3, respectively. The Archimedean spiral is introduced to improve the gain of the composite antenna in the case of the angular momentum of l=3. By analyzing axis ratio (AR) of the proposed antenna, the generated angular momentum of l=1 is spin angular momentum (SAM), and the angular momenta of both l=2 and 3 include SAM and orbital angular momentum (OAM). Simulated and measured results are given to demonstrate good performance including tunable modes, good purity and wide band.
本文设计了一种由八臂等角螺旋天线和八个阿基米德螺旋天线组成的复合平面螺旋天线，用于在宽频带内辐射携带可调角动量的电磁波。采用可调谐八路威尔金森功率分配器网络为等角螺旋天线提供三种馈电模式，从而使复合天线能够分别辐射角动量为l = 1、2和3模式的电磁波。引入阿基米德螺旋以在角动量为l = 3的情况下提高复合天线的增益。通过分析所提出天线的轴比（AR），产生的角动量l = 1为自旋角动量（SAM），l = 2和3的角动量都包括SAM和轨道角动量（OAM）。给出了仿真和测量结果，以证明其具有可调模式、良好纯度和宽频带等良好性能。
