Vortex Beam Generation Based on Plasma Reflect- Array Surface at Microwave Frequencies

Orbital angular momentum (OAM) is a promising feature of electromagnetic (EM) wave to increase the communication link capacity. It is possible to use the OAM over the whole spectrum from radio frequency to optic. EM waves would experience a vortex phase boundary while transmitting the data. According to the infinite number of vortex modes, there would be infinite data transmission in theory. Here, a plasma medium with a complex structure is exploited to construct the vortex phase plane at microwave frequencies. Plasma as the ionized gas transmits, reflects, and absorbs EM wave under some conditions. The ratio of plasma physical parameters with the impinging wave frequency presents the condition of wave interaction with the plasma medium. A reflector plane is realized with the help of multilayered low-pressure plasma. By radiation of a plane wave toward the reflector surface, vortex beams of several modes are realized. The controllability of plasma electron frequency makes it a reconfigurable reflect-array antenna for vortex beam generation. The design is based on the scattering theory of the dielectric plasma model for a vast frequency of 8-16 GHz. The proposed advanced EM structure to generate the vortex beams is simulated with a full-wave analysis that verifies the studied design.