Abstract: In the paper, a phased array antenna based on circularly polarized microstrip patch antenna coupled by cross slotsis designed. Firstly, the microstrip patch antenna element is designed, and the relation between the performance and theparameters of the structure of antenna is analyzed. By use of a 90° coupler, the two feed lines feeding to the cross slots are fed byequal amplitude and 90° phase difference, and the two ports of the 90° coupler can get the dual circular signals with oppositeRotational Direction. Secondly, the antenna element is measured, and the results show that the antenna offers 16% bandwidthunder axis ratio <3dB and 17% impedance bandwidth under VSWR<1.5, and the beamwidth is more than 87°. Finally, theconformal phased array antenna with the 5×5 array is simulated and measured, and the results show that the phased array antennacan scan to 60°, which can used as conformal satellite communication antenna.