In this paper, Aperture-coupled microstrip array antenna was designed and manufactured for satellite communication at Ka-Band. We analyzed a microstrip radiation element and designed power divider using $lambda$g/4 transformer and T-junction power divider. A manufactured Aperture-coupled $2 imes2$ microstrip array antenna has a resonant frequency of 20 GHz. The experimental results are as followings : resonant frequency of 19.62 GHz, VSWR 1.0692, return loss -29.61 dB, Bandwidth 1.76 GHz and -3 dB beamwidth $42^{circ}$.