A Wideband Circularly Polarized Metasurface Antenna Based on SIGW

A wideband circularly polarized (CP) metasurface (MTS) antenna based on substrate integrated gap waveguide (SIGW) is proposed in this paper. MTS is composed of four cross patches and a series of square patches. The characteristic mode theory is used to analyze the mode of the proposed antenna, and two characteristic modes with orthogonal and same direction current distribution are selected as the operating modes. Since both modes have wide bandwidth, the proposed MTS antenna can also achieve wide bandwidth. CP characteristics can be achieved by using a spoon-shaped feeding structure and a crossed-slot to excite two modes. Compared with the microstrip structure, the use of SIGW can better suppress the cross-polarization and back lobe of the radiation pattern. The simulation results show that -10 dB impedance bandwidth (IBW) of the antenna is 12.42 - 16.07 GHz (25.62%), 3 dB axial ratio bandwidth (ARBW) is 12.92 - 14.53 GHz (11.73%), and the peak gain is 12.9 dBic.