A High-Efficiency Quasi-4-bit Reconfigurable Metasurface Antenna for Continuous Beam Steering With a Simple Bias Circuit

This communication proposes a quasi-4-bit reconfigurable metasurface antenna (RMA) to realize continuous beam steering along with high aperture efficiency using a simple 1-bit bias circuit. Combining eight types of unit cells, a quasi-4-bit RMA capable of controlling 16 phase states using the same bias circuit as a 1-bit RMA is introduced. To enable continuous beam steering with high quantization efficiency, the RMA is designed based on a design algorithm combining the least-square method (LSM) and the genetic algorithm (GA). By adopting this design approach, the proposed RMA attained better quantization efficiency than a 1-bit RMA within the optimized steering range. To validate the design, a quasi-4-bit reflective RMA (RRMA) was fabricated, and its performance was measured for the −30° to 30° range in the E-plane. Compared with a 1-bit RRMA, the proposed RRMA improved the simulated and measured aperture efficiencies by 24.2% and 12.7%, respectively.