Electronically Reconfigurable Binary Phase Liquid Crystal Reflectarray Metasurface at 108 GHz

Abstract

We have proposed a preliminary design and computation results of a 20 by 20 elements reconfigurable liquid crystal (LC) based binary phase reflectarray metasurface for applications in THz wireless communication. Specifically, we performed full-wave simulations and theoretical calculations on the far-field patterns of our proposed device, and we also developed optimisation routines for both the antenna unit cell design as well as far-field pattern synthesis algorithms. The LC used was modelled after Merck's model GT3-23001. At optimal operation frequency of 108 GHz, the phase difference between ON and OFF state is 177 degrees, and the reflection amplitudes of both states are 0.88. We were able to demonstrate 60 degrees of beam steering, which was achieved together with a (single beam) RCS of -5.8 dBm2, when the device dimension is 20mm by 20mm. The operational bandwidth is plus or minus 2 GHz from central frequency of 108 GHz.

Modified Gerchberg-Saxton Iterative Algorithm for Reflectarray Metasurface Multibeam Pattern Synthesis

“…The green box is the feed source, the blue square is the RIS surface, the purple patch is the individual antenna elements on the RIS, the black circle is the farfield or observational space, which is a semi-sphere enclosing the top of the RIS. [12], [13], as well as other groups' work on diode-based refletarrays [7], [8], optimization algorithms such as the GA and PSO are used. These traditional algorithms take much longer to converge due to their nature of selection from populations/swarms, which requires the generation of large numbers of calculations at each iteration.…”