A broadband single-layer reflectarray antenna with split ring element

A broadband single-layer reflectarray comprising three-layer concentric split ring elements is proposed. The reflection phase is achieved by changing the flare angle of the inner and outer split rings. The resonance of the element is easily controlled by varying the relative relationships between the homomorphic patches. And the length of the split ring changes in the azimuth direction, which improves the utilization rate of unit space. The middle split ring acts as a parasitic structure with constant size, making the surface current distribution of the element more uniform to improve the element bandwidth. A reflectarray containing 256 elements is designed and tested. The measured results indicate that the peak gain is 25.3 dBi corresponding to the aperture efficiency of 42%. And the 1-dB gain bandwidth of the reflectarray of 21.7% is achieved.