A Compact Broadband Circularly Polarized Metasurface Antenna

ABSTRACT This letter demonstrates a design method of wide circularly polarized (CP) antennas by combining two separated characteristic modes of metasurface and the resonant mode of the feeding structure. The modal bandwidth of the metasurface is extended through separating a pair of degenerate modes of a metasurface, and two separated characteristic modes are selected as the candidate modes. A slot‐coupled feeding structure with a 90° phase difference is employed to excite the metasurface, and then a wider axial ratio bandwidth (ARBW) can be attained by assembling the resonant modes of the metasurface and the feeding structure. The dimension of the proposed antenna is 0.93 λ 0 × 0.93 λ 0 × 0.067 λ 0 . The measurements indicate that the antenna achieves a −10‐dB impedance bandwidth of 3.98–6.36 GHz (46%), a 3‐dB ARBW of 4.3–6.3 GHz (37.7%), and a maximum realized gain of 6.24 dBi.