A Ka-band Circularly Polarized Folded Reflectarray

In this paper, a high-gain circularly polarized folded reflectarray (CPFRA) centered at 37 GHz is developed for satellite and point-to-point communications. The proposed CPFRA is consisted of a circular polarization selective surface (CPSS) on the top, a broadband reflectarray panel on the bottom, and a broadband CP feed fulfilled using a meander-line circular polarizer and a linearly-polarized horn. The CPSS is designed based on the Pierrot structure, while the phasing element of the reflectarray is created by using a fan-shaped cross surrounded and coupled by a circular ring. The phasing element only requires a single layer which reduces the cost and complexity. In addition, the combination of the cross and ring enhances the resonance of the unit cell, which results in an improved bandwidth. The phase coverage of the unit cell is about 500°, while the reflection loss is maintained within 0.5 dB. The measured results show that the CPFRA can achieve a 3-dB gain bandwidth of 9.45%, an aperture efficiency of 30.6%, a 3-dB axial ratio bandwidth of 12.2%, and a peak gain of 26.8 dBic at the broadside direction.