An antenna comprises a main body and a cable connecting to the main body. The main body has a grounding portion, a cantilevered arm, a first connecting portion and a second connecting portion. The first connecting portion connects the grounding portion and the cantilevered arm. The first connecting portion is located at the upper side of the cantilevered arm and defines a first slot with the cantilevered arm. The second connecting portion connects the grounding portion and the cantilevered arm. The second connecting portion is located at the lower side of the cantilevered arm and defines a second slot with the cantilevered arm.