L-shaped slot coupling-fed low-profile broadband circularly polarized patch antenna with metasurface

Metasurface-based circularly polarized (CP) patch antenna with broadband property is proposed and analyzed in this paper. L-shaped slot coupling method is adopted to feed a 4 × 4 equally divided patch antenna (EDPA). By optimizing the geometry of the feeding structure, broad CP bandwidth is achieved which is much wider than the patch-truncated type. One prototype is fabricated for verification and the results show that the proposed antenna has a wide impedance bandwidth, which is 55.4% ranging from 4.66 to 8.23 GHz (S11 < −10 dB). The 3-dB AR bandwidth is 23.6% from 5.6 to 7.1 GHz, among which a good right-handed circularly polarized radiation is obtained. Furthermore, the gain variation is small (7.3–8.1 dBic).