Abstract: A three-dimensional antenna includes an L-shaped grounding element and an L-shaped radiating element. The grounding and radiating elements are arranged in a U shape. The grounding element includes a first grounding segment, a second grounding segment extending from the first grounding segment, and a short-circuit point disposed at the second grounding segment. The radiating element includes a first radiating segment opposite to the first grounding segment, a second radiating segment extending from the first radiating segment and adjacent to the second grounding segment, a feeding point disposed at the second radiating segment, and two radiator arms being able to generate respective resonant frequencies.