In this work, based on the switchable polarization conversion metasurface (SPCM), the dual functions of high gain right-handed circularly polarized (RHCP) radiation and wideband 10 dB radar cross section (RCS) reduction stealth are achieved in one structure. As the key component to achieve good radiation and low RCS, the proposed SPCM unit consists of the asymmetrical Jerusalem Cross top layer and switchable metal plate bottom layer separated by an air space. Then the SPCMs are arranged in a chessboard configuration and placed above a patch array antenna with the sequentially rotated feeding network. When p-i-n diodes are on, low RCS is implemented by 180° (±37°) reflection phase differences between two neighboring SPCM cells. When p-i-ns are off, the chessboard SPCM provides a transmission window for highly directional RHCP wave radiation.