Broadband Single-Layer Reflectarray Antenna Employing Circular Ring Elements Dented With Sectorial Slits

A broadband single-layer reflectarray antenna comprising circular ring elements dented with sectorial slits is presented. The sizes of circular rings are fixed and equal for all elements, while the variation of the reflected phase is obtained by varying the lengths of the sectorial slits dented within the circular rings. In this arrangement, the rapid geometric variations among the neighboring elements encountered in conventional reflectarray antennas can be prevented. The proposed element can yield a linear reflected phase together with a high reflected magnitude and important geometric parameters are examined to gain an insight into its broadband operation. Using the proposed unit cells, a 25̊ offset-fed reflectarray containing 529 elements with a grid periodicity of 0.3λ at 10 GHz, is designed, built, and tested. Experimental results indicate that the designed reflectarray antenna can realize a broad 30% 1-dB gain bandwidth with a 58.3% aperture efficiency. In addition, good sidelobe and cross-polarization levels in the ranges of 17.5 dB and 32 dB are also achieved at 10 GHz.