Circular-Polarized Metal-Only Reflectarray With Multi-Slot Elements

A circular-polarized metal-only reflectarray operating at 20 GHz is reported in this article. The reflectarray uses a novel multi-slot element that supports both left-hand and right-hand circular polarization for applications such as satellite communication. The element maintains a full phase coverage of 360° for both polarizations over a wide bandwidth spanning from 18 to 24 GHz (30%). Moreover, the square slot of the element allows the antenna to maintain a low axial ratio (<; 2 dB) over a large bandwidth. As a result, the 3-dB axial ratio bandwidth far exceeds the 1 and 3 dB gain bandwidths. The maximum simulated loss introduced by the reflectarray element was 0.9 dB at 24 GHz. The measured gain of the fabricated 20λ
₀
diameter (300 mm) reflectarray was 31.4 dB with a 1 and 3 dB gain-bandwidth of 6.8% and 10.1%, respectively, for each polarization. Measurement results illustrate excellent agreement with simulation. This reflectarray, which supports both polarizations, has both a polarization diversity and an increased bandwidth for satellite applications.