Improvement of sensitivities of concentric single-layer elements for the design of reflectarrays using split double-ring

In this paper, a broadband single-layer microstrip reflectarray element composed of a split double ring patch printed on composite substrate of low-cost, lossy materials FR4 and foam is presented and compared with the double square ring patch. The analyses are performed using the CST Microwave Studio software package. The proposed structure offers a slope value of 60°/mm, while the phase range is 450°. The 1 dB drop gain bandwidth of 19.5% over the frequency range of 12.4 GHz -15.1 GHz.