The basic methods and limitations of traditional C-band antennas are described, a mocrostrip type sinking cavity airborne C-band antenna is proposed. The antenna solves the influence of traditional non-conformal airborne antenna on aircraft air load by conformal method, and improves the environmental adaptability of the antenna. Based on the analysis and comparison of different design method of C-band antenna, an implementation method of airborne antenna with good performance and strong adaptability to the environment is proposed and verified. The simulation data are basically consistent with the measured results. The antenna can realize omnidirectional radiation, and the gain of antenna is ≥0 dBi in the effective working frequency band and the Angel of pitch is 45°~90°and the azimuth is -180°~180°.