Conformal antenna structure(CAS), also called the smart skin antenna structure , is a kind of multifunctional structure with the integration of airborne antenn a and a composite sandwich structure. It possesses the functionalities of load- bearing, shapemaintaining, stealthy, and communication together. This study is focused on the mechanical tests on a broadband conformal antenna structure with the integ ration of a planar spiral antenna. In-plane compression test and three-point bending test are conducted. According with the test results, the broadband conformal antenna structure has a superior mechanical performance compared with the ordinar y composite sandwich structure. Its compressive stiffness and strength are 112% and 95% higher than the corresponding values of the normal composite sandwich panel, while its bending stiffness and strength increase by 26% and 17%, respectively. The typical failure modes under compression and bending are changed from skin-core debonding only to multiple bonding surface failure combined with local skin fracture and core crushing and fracture.