A Varactor-Based and Dual-Polarized Reconfigurable Reflectarray with 2-Bit Phase Resolution

A varactor-based 2-bit dual linear-polarized reconfigurable reflectarray (RRA) is presented, featuring a unit cell with a cross-shaped structure on the top layer and a ground plane on the bottom layer. Each unit cell includes two orthogonally arranged varactors, independently biased via bias vias to generate different reflection phase shifts. Four distinct phase states are used to achieve a 2-bit phase resolution. A 16 × 16 unit cell RRA is designed and analyzed, showing that it can achieve ±60º beam steering for both linear polarizations. The maximum gain is 16.65 dBi at broadside, with cross-polarization levels below -14 dB. As the beam scans away from broadside, the gain decreases approximately as cos(θ). Compared to a 1-bit configuration, the proposed 2-bit RRA shows improved performance in gain, sidelobe levels, and beam direction accuracy.