Abstract: In this paper, a space-borne circularly polarized phased array antenna operating at X band is presented. The feeding probe and connector of the antenna element are integrated to eliminate solder joints, which can significantly improve the reliability of the array. At the same time, the metal cavity structure is loaded around the array elements, which reduces the mutual coupling between the adjacent elements, broadens the antenna beam, and improves the scanning gain of the array. The array is fabricated with a low-cost all-metal structure, which can realize the homogeneity of temperature and internal heat radiation of the phased array. The array itself has strong space resistance to radiation, and can also provide good radiation shielding for active devices inside the phased array. The active components and feeding network are designed using tile architecture, which provides the phased array with lightweight and low profile. The designed phased array antenna has a wide angle scanning capability of ±60° and a relative operating bandwidth of 4%.