Improvement of sensitivities of single-layer multiple ring elements for the design of reflectarrays

This paper analyzes several types of single layer phasing elements for their use in the design of reflectarrays. In this work, efforts focus on reducing the sensitivity of the design curves, improving the frequency response and behavior with manufacturing tolerances. Multiple concentric square rings with varying distance between rings and a hybrid phase element consisting of an external ring with an internal patch have shown improvements in the sensitivity. Finally, an evolutionary structure formed by patches which evolve into rings has been studied. This structure shows a phase range as wide as the concentric rings with a much lower sensitivity. All the analysis have been carried out using a tool based on CG-FFT.