Design of Wideband High-Efficiency Circularly Polarized Folded Reflectarray Antenna

This communication presents a wideband high-efficiency circularly polarized (CP) folded reflectarray antenna (FRA) based on the CP selective surface (CPSS). The proposed CPFRA is comprised of a simple CPSS on the top layer, a wideband reflectarray plane on the bottom layer, and a wideband planar CP antenna as the primary source. First, the simple CPSS based on the traditional Pierrot structure is designed. The CPSS can reflect one CP wave, while it can transmit its orthogonal CP wave. Then, a subwavelength element is used to design the wideband reflectarray, and a wideband planar CP microstrip patch array is selected as the feed. According to the ray tracing principle, the distance between the upper CPSS and the bottom planar reflectarray is reduced to half of the distance between the planar reflectarray and the imaginary feed approximately. At last, we design a wideband high-efficiency CPFRA. Measured results of the fabricated prototype reveal that its maximum gain at 10 GHz is 27.8 dBic, its 3 dB gain bandwidth is 15%, its 3 dB axial-ratio (AR) bandwidth is 23%, and its maximum aperture efficiency is about 45.4%. Good broadband and low-profile characteristics make the proposed CPFRA have potential value in some wireless communication system.