A High Efficiency Metasurface-Engineered Antenna for Multiplexing OAM Beam Generation

Abstract

Vortex electromagnetic (EM) beam carrying orbital angular momentum (OAM), is extremely potential to be applied in wireless communication systems to increase channel capacity, attributing to its extra freedom of degree of theoretical infinite orthogonal topological charges ( l ) [1] . However, in radiofrequency and microwave region, circular antenna array, as the common method to generate vortex beam with multiple OAM modes, its complex feeding network increases the difficulty of fabrication and integration [2] . Through adopting the ability of metasurface to accurately manipulate the EM properties, versatile OAM modes can be stimulated by metasurface-assisted antennas [3] . In this paper, a highly efficient metasurface-engineered antenna is proposed to generate vortex beam carrying five distinct integer and fractional OAM modes in microwave region, the mechanism schematic is shown in Figure 1a . The integer and fractional OAM with topological charge l =1, 1.5, 2, 2.5, 3 can be separately generated in total, where the combination of polarization states (left-handed circular polarization, LHCP; x-linearly polarization, x-LP; right-handed circular polarization, RHCP) of the transmitting antenna and receiving probe acts as the key to alter the output OAM modes.