Phase Quantized Metasurface Reflectors for X-band Laguerre Gaussian Vortex Beam Generation

Abstract

From last two decade, there is an exponential growth in consumption of available bandwidth in the radio frequency spectrum. To challenge this issue, improvement in channel capacity is getting huge research attention. Laguerre-Gaussian vortex beams are one of the solution to challenge so-called Multi-Input-Multi-Output (MIMO) technology. However, designing compact portable antennas to generate vortex beams at radio frequencies is still a challenge. We proposed two metasurface reflector models (Track and sector-wise distribution) based on 3-bit phase quantized meta-element analysis to generate fundamental Orbital Angular Momentum (OAM) vortex modes. A microstrip antenna is used as feeding element instead of conventional horn to reduce overall reflector size. Simulated E-field distribution clarifies the spatial vortex mode behavior at X-band. Experimental results of fabricated prototypes at 9.5 GHz, 10 GHz, and 10.5 GHz agrees with simulated far-fields which indicates a broadband characteristic.