A Reflectarray based on Minkowski Ring Elements Backed by Frequency Selective Surface

In this paper, a novel subwavelength and FSS-backed reflectarray element is proposed. The element is composed of a Minkowski ring and a square ring. Due to its self-similar structure and unlimited space filling property, fractal element can achieve smaller element spacing and better phase performance. With the proposed reflectarray element, the element spacing is reduced to 0.38λ
₀
. The traditional metal ground plane is replaced by a frequency selective surface (FSS) that reflects the electromagnetic waves in the working frequency band and provides favorable conditions for smoother and linear reflection phase curve. A prototype with an aperture size of 220 mm × 220 mm is designed, fabricated and measured. The simulated results show that the antenna gain is 18.5 dBi at 5.8 GHz and a 15.7% 1-dB gain bandwidth is realized. Meanwhile, the simulated cross polarization and sidelobe level are -28.8 dB and -13.9 dB, respectively.