Abstract: A novel frequency spliced metasurface consisting of absorptive/transmissive frequency selective surface (ATFSS) and 1-bit polarization conversion metasurface (PCM) is proposed and applied in radar cross section (RCS) reduction for microstrip array antennas. In the low-frequency band, the ATFSS provides good transmission performance within the operating band of the antenna and reduces the RCS of the antenna by absorbing electromagnetic waves outside the band; in the high-frequency band, the RCS reduction bandwidth of the antenna continues to be broadened by the low scattering characteristics of the 1-bit polarization conversion metasurface. The entire frequency spliced metasurface exhibits an absorption-transmission-absorption-scattering frequency response. In addition, the array antenna loaded with frequency-spliced metasurfaces significantly increases the gain compared to a normal microstrip array antenna. Simulation and test results show that the antenna has an impedance bandwidth of 8.65-8.85 GHz and a peak gain of 15.16 dBi. An out-of-band single-site RCS reduction of more than 6 dB is achieved in the 3.8-21.5 GHz band.