An antenna of reduced size but of multiple functions according to manual adjustment includes a side frame made of metallic material, a feeding portion, and a moving module. The side frame defines first and second gaps each passing through the side frame to form at least one radiating portion. The feeding portion can feed current to either of the radiating portions. The metallic and movable moving module including an extending portion is movable relative to the side frame. In a first position, the extending portion is not connected to any radiating portion, and when moved to a second position, the extending portion is connected to one of the radiating portions.