A Novel Microstrip Rectangular-Patch/Ring- Combination Reflectarray Element and Its Application

In this letter, a novel single-layer microstrip reflectarray element composed of a rectangular patch and a rectangular ring is presented. Ansoft HFSS and CST Microwave Studio, two different kinds of electromagnetic simulation softwares, are used to analyze the reflect phase for the designed element. To validate the proposed design and evaluate its performances, a parametric study is carried out. For the optimal parametrics, the proposed structure offers a slope value of 40deg/mm, while the phase range is in excess of 450deg. Then, a prime-focus 45-element microstrip reflectarray with the proposed element is designed and measured. The highest measured gain is about 20 dBi with 1 dBi drop within 30% bandwidth at the center frequency of 10 GHz.