Provided is an ultra-wideband dipole antenna. In one embodiment, the antenna comprises a first outer sleeve, an intermediate sleeve surrounded by the first outer sleeve, a second outer sleeve above the first outer sleeve, a conductive interconnection interconnected the outer sleeves, and an inner coaxial conductor surrounded by the intermediate sleeve. A distance between the first outer sleeve and the intermediate sleeve can be changed for adjusting the generated capacitance for obtaining a required impedance matching in the resonance mode of an antenna operating bandwidth and an ultra-wideband characteristic. The antenna is particularly suitable for operating in a frequency range of 2.1 GHz to 11.7 GHz.