Millimeter-wave Reflectarray for Beam-Steering Applications

In this paper, we describe the development of a millimeter-wave reflectarray intended for use in a millimeter-wave identification or imaging applications. Design, simulations, and millimeter-wave near-field measurements of the reflectarray are presented. An in-house genetic algorithm is used in determining the required phase shift by the reflectarray elements. The elements are realized in a lithographic process and are based on a conductor-backed coplanar waveguide patch antennas with a phase shifter attached to them. Prior the fabrication, the element is optimized based on full-wave simulations. Static 120-GHz offset-fed reflectarrays preceding the active ones have been fabricated and characterized at millimeter-wave near-field measurement range. With these prototypes, the feasibility of both the genetic algorithm and the fabrication process is proven successful, although in some part some iteration will still be required. The measured beam patterns of the reflectarray are in line with theoretical predictions given by the genetic algorithm when unidealities of the reflectarrays are taken into account.