A Wideband 1.5-Bit Unit Cell for Reconfigurable Reflectarray Design

This paper presents a low-complexity, wideband unit cell design suitable for reconfigurable reflectarrays (RRAs). To overcome the challenges of high implementation complexity associated with high-bit quantization, and the performance degradation resulting from one-bit quantization, a 1.5-bit phase quantization approach is proposed. The developed unit cell can operate in multiple modes to realize reflection phase delay, resonance tuning, and true-time delay, controlled by two PIN diodes. By switching the states of these diodes, the unit cell provides four reflection states. Wideband operation is achieved by selecting appropriate states across the frequency range to ensure continuous phase coverage. To validate the proposed concept, a unit cell was designed and simulated. The simulation results demonstrate stable three-phase responses with low reflection amplitude variation under different incidence angles across the 13.4-19.2 GHz frequency band.