Design of a Broadband Single-Layer Linearly Polarized Reflectarray Using Four-Arm Spiral Elements

A single-layer broadband reflectarray antenna with four-arm spiral elements is presented. Large-range reflection phase has been obtained by varying the length of the arms. The effects of different incident angles on the four-arm element are studied first. Then, a 441-element offset-fed linearly polarized reflectarray is fabricated and measured. The measured results agree well with the simulated results. Measured results show the gain level of 28.35 dB with 1-dB gain bandwidth of 28.7% (12.41-16.31 GHz) and aperture efficiency of 60.2% at center frequency of 13.58 GHz.