Development of Two-Dimensional Steerable Reflectarray With Liquid Crystal for Reconfigurable Intelligent Surface Applications
X. Li, Hiroyasu Sato, Hideo Fujikake, Qiang Chen
Abstract
In this article, a reconfigurable reflectarray (RA) system which can steer reflected beam at two dimensions based on liquid crystal (LC) technology at Ka band is proposed. In the RA system, an individually controlled RA unit is come up with and utilized to generate a <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$12\times12$ </tex-math></inline-formula> elements RA, a novelty bias network composed of metalized vias holes and driving lines are proposed and used to control each element independently, and a Ka band standard horn antenna is offset 20° at H-plane as the primary feed. The manufactured RA model is checked for the reconfigurability with bias voltage under the microscope, then the model is measured that a continuous phas-varying ability can be achieved. During the measurement of beam steering, far-field patterns at E-plane from 0° to 35° are measured; and scanning at H-plane can cover from 0° to 40°; for the special beam direction <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\varphi _{a}$ </tex-math></inline-formula> = 115°, <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\theta _{a}$ </tex-math></inline-formula> = 15°, a near-field measurement is used and proves that the 2-D beam scanning is possible. Then LC RA is applied as reconfigurable intelligent surface (RIS) in the simulated narrow street model, and the results show that it could indeed enhance the received power of electromagnetic waves. The innovation of this study is to propose a single controllable LC RA unit and a corresponding bias network composed of metallized vias and driving lines; thus, each element in RA can be controlled to change reflection coefficient and beam steering of greater freedom with LC technology is achieved, which is a potential RIS and provides a possible solution for the beam scanning property.