Abstract: An antenna structure includes a first ground element, a feeding element, a shorting element, a parasitic tuning element, a second ground element, a first parasitic element, a second parasitic element, and a dielectric substrate. The feeding element is coupled through the shorting element to the first ground element. The parasitic tuning element is coupled to the first ground element. The parasitic tuning element is at least partially surrounded by the feeding element, the shorting element, and the first ground element. The second ground element is adjacent to the feeding element. The first parasitic element and the second parasitic element are coupled to the second ground element. The feeding element, the shorting element, the parasitic tuning element, the first parasitic element, the second parasitic element, and at least one of the first ground element and the second ground element are disposed on the dielectric substrate.