An antenna includes a substrate, a radiation element, a feeding element, a connection element, and a matching circuit. The substrate includes a first side and a second side. The first side includes a short point and a grounding point. The radiation element includes a first radiator, a second radiator, and a first metal arm. The first radiator and the second radiator are parallel to the first side. The first metal arm is coupled to a joint of the first radiator and the second radiator. The feeding element is coupled between the first metal arm and the grounding point. The connection element is coupled between the first metal arm and the short point. The matching circuit includes a second metal arm and a matching element. The second metal arm extends from the first metal arm. The matching element is coupled to the second metal arm.