A Metal-Only Folded Reflectarray Antenna

This letter presents a metal-only folded reflectarray antenna, consisting of three components, namely a pyramidal feed horn, a lower reflectarray, and an upper polarizer, which are all made of metal. The lower reflectarray consisting of planar polarization rotation elements focuses the beam and twists the incoming wave polarization perpendicularly so that the reflection wave can pass through the upper polarizer. With the adjustment of geometrical size, four elements with an equal phase interval of 45° are achieved. In addition, along with their mirror counterparts, 3-bit phase shifting elements covering 0°, 45°, 90°, 135°, 180°, 225°, 270°, and 315° within 9–10.6 GHz can be realized. For validation, a metal-only folded reflectarray with 610 elements is built and tested. Based on experiment results, 1 dB gain bandwidth is 16% while the peak aperture efficiency is 45%. These promising properties together with the low-profile metal-only structure make the proposed design a great candidate for space applications.