A novel tightly coupled dipole array antenna with high power and broadband is proposed in this paper. On the basis of conventional tightly coupled dipole array antennas, and by adopting an all-metal structure design, an integrated design of antenna matching layer and sealing layer, and a method of adjusting the antenna structure, a high-power and broadband performance of such an array antenna is obtained. The simulation results show that the standing wave ratio of the array antenna is less than 2 at the broadside in the range of 0.8-4.0 GHz. And the power capacity of an element antenna reaches 0.12 MW within the size of 16 mm × 32 mm in the space full of SF₆ at one atmospheric pressure. Moreover, the power capacity of the 10×10 array antenna composed of 100 elements can reach 12 MW within the size of 320 mm × 640 mm in the space full of SF₆ at one atmospheric pressure. In addition, the array antenna can achieve a wide-angle scan of 45°. The proposed array antenna provides a solution for high-power microwave broadband antennas to achieve a broadband, large-angle scanning, compact, miniaturized, and low-profile performance.