Broadband circularly polarized antenna using metasurface

A rectangular microstrip antenna over a metasurface is proposed for circularly polarized radiation across wide frequency range. The proposed antenna comprises a rectangular microstrip radiator, a metasurface with 7 × 7 unit cells, and a coaxial feed probe. The prototype antenna with an antenna volume of 78 mm × 60 mm × 4.8 mm achieves a circularly polarized bandwidth (3-dB axial ratio) of 19.5% (3.7GHz-4.5 GHz), VSWR ≤ 2 bandwidth of 34.2% (3.4 GHz-4.8 GHz) with maximum gain of 7.4dBic.