Recent Developments of Wideband and Multi-Band Dual-Circularly-Polarized Reflect-Arrays

The recent developments of dual-circularly-polarized (dual-CP) reflect-arrays (RAs) at microwave and millimeter-wave frequencies are reported. In the first part, dual-CP RAs with a wide operational bandwidth are described through several demonstrating examples. Two strategies are employed - one utilizing only Berry phase with two functional layers and the other exploiting both dynamic and Berry phases for dual-CP beamforming with a single functional layer. In the second part, by incorporating shared-aperture techniques into the RA cell alignment, dual-band dual-CP RA cell designs are described, which have four degrees of freedom in terms of reflective phase control. The designs are numerically validated by diffraction analysis of a linear gradient array of dual-band dual-CP RA cells, exhibiting reflective beam bending with both simultaneous polarization and frequency diversities.