A wideband antenna is studied in this paper using a multi‐layer metasurface structure and implementing a periodic array for enhancing the gain. The performance of the multilayer antenna is improved by using a sub‐wavelength Fabry‐Perot cavity (FPC). The feeding and main radiation patches of the microstrip antenna are placed separately on two substrates, which are stacked on top of each other without an air‐gap in between. Two other substrates are placed within an optimized distance on top of the microstrip antenna. This structure, which has a double‐sided periodic array configuration, includes a capacitive artificial impedance surface (AIS) on one side, and an inductive partially reflective surface (PRS) on the other side of the substrates. Making use of this configuration increases the gain up to 18 dBi and widens the frequency bandwidth. Moreover, measurement results indicate a frequency range from 10.8 GHz to 15 GHz with an S11 less than −10 dB.