On the Use of Metallic Polarization Conversion Element With Continuous 360° Phase for High- Efficiency All-Metal Planar Folded Reflectarrays

In this letter, a high-efficiency planar all-metal folded reflectarray adopting polarization conversion element with a continuous 360° phase is proposed. It contains three parts, a bottom planar reflectarray for polarization conversion and beam focus, a top grid polarizer for selection of polarization, and a feed horn for illumination, which are all implemented by metal. By varying bottom reflectarray element's geometrical dimensions as well as mirroring its structure, a linear and continuous 360° phase span is achieved, leading to a good phase compensation accuracy when designing the array. For proof of concept, an all-metal low-profile folded reflectarray composed of 625 elements is developed. The results from experiments reveal that the proposed design exhibits a high aperture efficiency of 62.4% with 1 dB/3 dB gain bandwidth of 12%/22%, respectively. These favorable features along with the low-profile all-metal configuration make the design very suitable for various high-gain communication systems.