Metasurface-based circularly polarized patch array antenna using sequential phase feed

This paper describes a low-profile broadband 2×2 metasurface-based circularly polarized (CP) array antenna using a sequentially rotated series-parallel feed. The single element is a truncated corner square patch sandwiched between the ground plane and the metasurface of a lattice of 4×4 metal plates. These antennas are incorporated with the feeding network to achieve broadband operation. The 2×2 metasurface-based array antenna with an overall size of 64 mm × 64 mm × 2.34 mm (~1.17λ₀ × 1.17λ₀ × 0.043λ₀ at 5.5 GHz) has a |S₁₁| <; -10 dB bandwidth of 4.56-6.98 GHz (41.94%) and 3-dB axial ratio bandwidth of 4.67-6.39 GHz (31.1%). The array antenna yields a broadside left-hand CP radiation with a peak gain of 11.6 dBic, a 3-dB gain bandwidth of 4.67-6.36 GHz (30.6%), and a radiation efficiency of > 88%.