The high integration of electronic devices has become increasingly demanding for miniaturized antennas, especially in systems for satellite communications and military radars, which also requires antennas with higher gains. In this paper, a high-gain array antenna is designed with small size. The unit is fed by a coupled microstrip line. The simulation results show that the reflection coefficient is less than -10 dB in the frequency range of 4.93 GHz - 5.05 GHz. Also, the gain at 5 GHz is 14.75 dBi and the aperture efficiency is 85.6%. It is only 1/15 the size of a conventional array antenna.