An antenna device includes a first dielectric substrate made of a high dielectric coefficient material, a plurality of first contact pads fastened on a periphery of a top surface of the first dielectric substrate, a plurality of second dielectric substrates made of the high dielectric coefficient material, and a plurality of Yagi-Uda antennae respectively disposed on top surfaces of the second dielectric substrates. The second dielectric substrates are fastened on the first dielectric substrate. Each of the Yagi-Uda antennae has a drive, and a plurality of directors disposed in an outside position of the drive and spaced from an outer side of the drive. The directors are shorter than the drive, and the directors are arranged along a direction of being gradually away from the drive and gradually become shorter. An inner side of the drive defines a signal feed point.