A novel design for patch antenna, which can obtain low radar cross section (RCS) and high gain performance simultaneously, is proposed on the basis of metamaterial superstratum. The superstratum consists of two metallic layers with different patterns on both sides of a dielectric substrate. Low reflection and transmission are obtained from the upper surface which can absorb most of the incident wave to reduce the antenna RCS. The bottom surface, which has partial reflectivity, is used to construct a Fabry-Perot resonance cavity with the ground plane of the patch antenna to improve its directivity. Simulated and measured results show that the proposed antenna can achieve an obvious RCS reduction in a broad frequency band ranging from 2 to 14 GHz and the maximum reduction can reach 28.3 dB, and yet the gains of the antenna are all enhanced and some are even enhanced maximally by 4.3 dB in the working frequency band compared with the original antenna.