Design of Single-Layer Circularly Polarized Reflectarray With Efficient Beam Scanning

Abstract

This letter presents the design of wideband, low-cost, single-layer, ultrathin, beam-scanning circularly polarized reflectarray (CP-RA) antenna with high-radiation characteristics. To obtain efficient single and multiple CP beams, a subwavelength unit cell based on Pancharatnam–Berry (PB) geometrical phase was used to increase the beam scanning efficiency. PB unit cell with periodicity of 0.28 λ o and ultrathin thickness of 0.11 λ o is used to achieve the required phase correction across the reflectarray aperture to produce a collimated right-hand circularly polarized (RHCP) beam in the desired direction. The unit cell has three plasmonic resonances and the proposed CP-RA consists of 43 × 43 PB unit cells and occupies an area of 215 × 215 mm2. Both simulation and experimental results show that the proposed CP-RA produces RHCP pencil-beam in the desired direction with a 1 dB gain bandwidth (BW) of 24.5% from 17 to 24.5 GHz, 3 dB gain BW of 46.15% from 15 to 24 GHz, peak aperture efficiency of 49.93%, 3 dB axial ratio (AR) of 46.15%. Furthermore, a beam scanning with 70° (±35°) scanning angle is achieved with gain scanning loss of less than 3 dB and beam squint of less than 1.3° within the whole frequency band and for all scanning angles.