Design and Optimization of a Single-Layer Dual-band Circularly Polarized Reflectarray Antenna Producing Three Beams

This paper introduces a novel single-layer, dual-band circularly polarized reflectarray (RA) with the unique ability to generate three beams. Incorporated within the design approach are the variable rotation technique (VRT) and the element size variation technique (ESVT), both optimized to yield superior radiation performance. The fabricated prototype exhibits beams at elevation angles of 9° for right-hand circular polarization (RHCP), and 15° for left-hand circular polarization (LHCP) within the Ka-band (27.5-30.5 GHz). Moreover, in the K-band (18.7-20.2 GHz), an additional beam for RHCP can be generated at an elevation angle of 12°. A meticulous optimization process was conducted across all element configurations to minimize cross-polar reflection. Based on comprehensive simulation and precise measurement results, the reflect-array proves to suppress cross-polarization efficiently below 19.0 dB, while simultaneously attaining a 1-dB gain bandwidth exceeding 8.2% in both bands. These features enhance the application potential in wireless communication systems, particularly in dual-band and beam control scenarios.