A dipole antenna includes a substrate, a first region and a second region, which is used for frequency with wavelength λ. The substrate is flat rectangular and insulating material, which has a substrate width W which is at least 2.5 mm and a substrate length L. The substrate width W, the substrate length L and the wavelength λ complies with the formula: L/W=λ(±10%). The first region and the second region is conducting material, the first region is disposed on the substrate and shifting to one side of the substrate, the second region is disposed on the substrate and shifting to another side of the substrate. Part of the first region is disposed adjacent to part of the second region and an adjacent region is formed between and a coupling effect is reduced.