Reconfigurable Dual-Band Circularly Polarized Reflectarray With Small Frequency Ratio Incorporating Precoding Technology

This communication proposes a dual-band circularly polarized (CP) reflectarray design scheme based on precoding technology. Compared with traditional co - aperture arrays, this design allocates two circularly polarized elements to different frequency channels at 23 GHz and 26 GHz, respectively. This enables independent manipulation of dual-band beams, with the higher and lower bands boasting a mere frequency ratio of 1.13. By introducing the element sequential rotation technology and 1-bit active coding, the axial ratio (AR) bandwidth of the array is effectively improved, and the beam scanning ability is realized. To validate its performance, a 10 × 10 reflectarray prototype was simulated and fabricated. Experimental results demonstrate that the array achieves a beam scanning range of ±30° in the two-dimensional (2D) plane. At the 0° direction, the peak gains for the 23 GHz right-hand circularly polarized (RHCP) and 26 GHz left-hand circularly polarized (LHCP) beams are 18.12 dBic and 18.35 dBic, respectively. The 3-dB gain bandwidths are 7.8% (22.3 to 24.1 GHz) and 7% (25.0 to 26.8 GHz), while the 3-dB axial ratio bandwidths are 7.05% (22.15 to 23.77 GHz) and 5.85% (25.04 to 26.55 GHz). The aperture efficiencies are 13% @ 23 GHz and 10.85% @ 26 GHz, respectively.