W-band microstrip reflectarray with double-cross element for bandwidth improvement

A broadband microstrip reflectarray is designed with the proposed element at W-band. The element consists of two cross-shaped resonators. Based on the analysis on the resonance mechanism of the double-cross element, the reflection phase of the element is controlled to achieve broadband characteristics by adjusting the dimensions of the element. Using the proposed element, a reflectarray with diameter of 50 mm is designed at f₀ = 95 GHz. At f = f₀, the peak gain of 31.73 dBi is achieved with aperture efficiency of 66.1%. Also, 1-dB gain bandwidth of 15.9% is achieved at W-band.