Spatially Multiplexed Non-vortex OAM Beams for Long-Range High Data Rate Communications

In this paper, it is shown that multiplexed orbital angular momentum (OAM) beams without a radiation null, referred to as non-vortex OAM beams, can be generated using a uniform circular array (UCA) with sequentially rotated antenna elements. An UCA, with N antenna elements, is formed by spatially multiplexing two N/2-element UCAs having the same array radius. The two N/2 -element arrays are independently excited and their antenna elements sequentially rotated, to result in several configurations, each generating multiplexed non-vortex OAM beams. This approach is demonstrated via CST Microwave Studio simulations using a UCA with 8 antenna elements, exploring all sixteen configurations of excitation phases and rotations. It is also shown that several configurations of excitation phases and rotations result in wideband circularly polarized beams, which are highly desired in communications applications. Such multiplexed non-vortex OAM beams can enable long-range and high data rate OAM communications, realizing their full potential in enhancing spectrum efficiency.