Light-Controlled Large-Scale Wirelessly Reconfigurable Microstrip Reflectarrays

Abstract

In this article, the concept and design of light-controlled large-scale wirelessly reconfigurable microstrip reflectarrays are proposed. Unlike conventional electrically reconfigurable microstrip reflectarray antennas (RAs) that control the aperture phase distribution by conducting wires for transmitting control signals, the proposed method utilizes light to control the ON- and OFF-state of the integrated positive-intrinsic-negative (p-i-n) diodes wirelessly and binaurally through light-sensitive resistance of photodiodes (PDs). The concept is validated by simulation first, where a 1 bit 32 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\times32$ </tex-math></inline-formula> wirelessly reconfigurable microstrip RA is designed at 10 GHz with a beam-steering range of ±60° for sidelobe levels < −10 dB, marking a record of 1024 elements with a tri-layer configuration. Experimentally, the light-control scheme is further validated by a smaller porotype of 256 elements, where a light-controlled beam steering from 30° to 45° is demonstrated. Compared with conventional wired reconfigurable microstrip RAs, the proposed method resolves the wire-routing complexity on the RA and offers a new possibility for further improving the maximum directivity, upper operating frequency, and the number of independently controllable polarizations of reconfigurable microstrip reflectarrays, paving the way for developing very-large reconfigurable intelligent surfaces (VRIS). Also, the proposed concept provides a new infrastructure for information exchange between light and microwaves.