A new broadband circularly polarized slot antenna using metasurface for C-band satellite communication application is proposed. The antenna has a size of 0. 46λ0× 0. 46λ0 and a thickness of 0. 06λ0（ λ0 is a free space wavelength with a frequency of 5. 25 GHz）. In the process of design

the working mechanism of metasurface circular polarization is analyzed by using equivalent circuit method

and the influencing factors of antenna circular polarization bandwidth are analyzed and the parameters scanning are carried out at the same time.The simulation results show that the relative bandwidth of the antenna is about 28. 6 %

the 3 d B axis ratio bandwidth is about 19 %

and the gain of the antenna is about 7. 9 d Bi in the impedance bandwidth. Radiation characteristics

radiation pattern and simulation results are given

which provide a new research direction for the research of broadband wireless communication.