A Wideband Circular-Polarized Triangular Element Metasurface Antenna Design for C-Band Based on Characteristic Mode Analysis

Based on the characteristic mode theory, this paper proposes a low-profile metastructure circularly polarized broadband slot-coupled microstrip antenna. The metasurface is composed of 4*4 cut Angle metal patch, the antenna is fed by gap coupling, the floor gap is double trapezoidal connection. Based on the theory of characteristic mode, the function of degeneracy mode of square radiating patch is analyzed, and the degeneracy mode is separated effectively, which provides the mode basis for realizing circular polarization broadband performance. The size of the antenna is 0.67 λ×0.67 λ×0.043 λ, where λ is the free-space wavelength at 5.0 GHz. The simulation results show that the -10 dB impedance bandwidth is 29.8% for frequencies from 4.33 GHz to 5.82 GHz and the 3 dB axial ratio bandwidth is 17.8% for frequencies from 4.93 to 5.82 GHz. This antenna achieves good circularly polarised broadband performance and has excellent application prospects in areas such as satellite communications.