Design of a broadband single-layer reflectarray antenna using double hexagonal rings and a hexapole

This paper proposes a novel subwavelength single-layer reflectarray antenna unit cell operating in X-band, composed of double hexagonal rings and a hexapole. This new cell is not sensitive to TE and TM polarizations. Infinite array approach has been used to determine the reflection phase curve. The proposed element has more than 575 degrees linear phase range in 8.5-11 GHz frequency band by varying the radius of the outer ring. The scattering parameters of an infinite reflectarray using the proposed element are measured by the waveguide simulator which takes into account the effects of the mutual coupling. A 277-element center-fed reflectarray antenna using this cell is designed, fabricated and measured to verify the broadband property of the proposed element. The measurement results show about 27.5% 3-dB gain bandwidth and 22.8 dB maximum gain at 10 GHz, which is equivalent to about 32% aperture efficiency.