Abstract: Stacked patch, aperture-coupled feeding are used to enhance the bandwidth of a dual-polarized microstrip antenna at Ku. Cavity in the substrate can effectively reduce antenna cost, but also to achieve a low equivalent dielectric constant. By using the unit designed, a 4-element array antenna is fabricated. Simulation results show that the relative impedance bandwidth of two ports( VSWR<2) is 20.5% and 20.1%. Respectively, and isolation degree is higher than 31dB, and the Cross-Polarization is better than -41dB and -46dB.