An antenna structure includes a dielectric substrate, a first radiation element, a second radiation element, a third radiation element, a fourth radiation element, a fifth radiation element, and a sixth radiation element. The dielectric substrate has an upper surface and a lower surface. The first radiation element, the second radiation element, the fourth radiation element, and the fifth radiation element are disposed on the upper surface of the dielectric substrate. The third radiation element and the sixth radiation element are disposed on the lower surface of the dielectric substrate. A positive feeding point is positioned at an end of the first radiation element. A negative feeding point is positioned at an end of the fourth radiation element. The third radiation element couples the first radiation element to the second radiation element. The sixth radiation element couples the fourth radiation element to the fifth radiation element.