Broadband Folded Reflectarray Antenna Using Single-Layer Cross-Polarization Conversion Subwavelength Elements

A broadband folded reflectarray antenna (FRA) is presented employing a novel single-layer cross-polarization conversion (CPC) subwavelength element in this letter. The proposed element has a very simple structure and consists of only a square ring resonator loaded with two splits, thereby realizing easy fabrication with low cost. By varying the length of the ring and mirroring the element, a 360° phase change range is achieved with low losses at the center frequency. These characteristics make the proposed configuration unique, as most of the reported FRA elements rely on complex and multilayer structures to realize the broadband CPC. Furthermore, an FRA using the proposed elements is designed and measured at 22 GHz. A good agreement between the simulated and measured results is obtained. The measured results demonstrate that the proposed FRA realizes a 1 dB gain bandwidth of 20.9% and a maximum aperture efficiency of 47.8%.