Wideband circularly polarized antenna using uniform and non-uniform metasurfaces

Abstract This paper presents a circularly polarized (CP) antenna employing both uniform and non-uniform metasurfaces to achieve wideband characteristics. The proposed antenna consists of a dual-feed CP antenna as the source element, a 4 $\times$ 4 metasurface lattice as the superstrate, and a sequential feed network. Initially, the performance of the antenna is analyzed using a uniform metasurface. Subsequently, by adjusting the size of the inner unit cells, the uniform metasurface is transformed into a non-uniform configuration. The proposed design with a uniform metasurface achieves a $-$ 10 dB impedance bandwidth ranging from 5.21 to 6.47 GHz (21.57%) and a 3-dB axial ratio bandwidth from 3.96 to 6.67 GHz (50.9%). The use of a non-uniform metasurface significantly improves the overall antenna performance, achieving a $-$ 10 dB impedance bandwidth and 3-dB AR bandwidth of 4.98 to 7.45 GHz (40%) and 2 to 7.26 GHz (113%), respectively. The optimized design with a non-uniform metasurface is fabricated and tested. Overall size of the antenna is 40 $\times$ 40 $\times$ 3.4 mm $^3$ (0.72 $\times$ 0.72 $\times$ 0.062 $\lambda_{0}^3$ ), where $\lambda_{0}$ represents effective wavelength at an operating frequency of 5.5 GHz. The simulated and measured results of the proposed antenna are found to be in good agreement.