Multiband antenna

A multiband antenna includes a ground plane, a dielectric substrate and a radiating metal portion. The dielectric substrate is located at one side edge of the ground plane. The radiating metal portion is disposed on one surface of the dielectric substrate and includes a first metal portion and a second metal portion. The first metal portion is substantially of an L-shape. One end of the first metal portion is adjacent to the side edge of the ground plane and is the antenna's feeding point connected to a signal source, and the other end of the first metal portion is an open end. The second metal portion comprises a U-shape portion. The second metal portion includes a first open end and a second open end, which are respectively located on two opposite sides of the open end of the first metal portion. The first open end has a first coupling gap between the first open end and the open end of the first metal portion, and the second open end has a second coupling gap between the second open end and the open end of the first metal portion. The second metal portion is further short-circuited to the ground plane by a shorting metal line.