Abstract: This paper focuses on the structure design requirements of large detection aperture in operational state and folded structure with compact size in transportation state for radar antenna. As a result, a deployable array antenna with a large fold-to-deploy ratio and light weight is proposed. The deployable array antenna consists of two main components, the deployment mechanism and the flexible thin-film antenna. The deployment mechanism adopts the configuration of serial four-bar linkage, and achieves a fold-to-deploy ratio of 19:1. After deployment, the linkage mechanism automatically "locks-in" and form a triangular truss structure, which ensures the structural stiffness of the mechanism. The flexible thin-film antenna is composed of patch elements, support foam, and a thin-film reflector, with a surface density as low as 0.98 kg/m². Structural rigidity and strength characteristics of the presented deployable antenna in its operational state were analyzed using finite element simulation method. The results indicate that the deployable antenna well satisfies the surface precision and structural strength requirements under a 5-level natural wind environment.