A C/Ka dual frequency dual layer circularly polarized reflectarray antenna with microstrip ring elements

This paper reports a dual frequency dual layer circularly polarized reffectarray operating, in the C and Ka bands. A 0.5-m right-hand circularly polarized planar refiectarray antenna is designed using microstrip ring elements of variable rotations to achieve a cophasal beam at broadside. The microstrip ring elements are more compact than the traditional rellectarray elements and can minimize blockage for the multilayer multifirequency applications. The highest efficiencies measured are 46% at 7.3 GHz and 38% at 31.75 GHz. The tested cross-polarization levels are -21 dB at 7.3 GHz and -29.2 dB at 31.75 GHz at the broadside direction. The tested results show that the designed ring element is suitable for both the single and dual layer applications with good bandwidth and circularly polarized performance.