An antenna includes a dielectric substrate, a grounding plane, first and second grounding elements, and first and second radiating elements. The grounding plane is formed on the dielectric substrate. The first and second grounding elements are formed on the dielectric substrate, have a curved shape and a size that are identical, and are connected to the grounding plane. The first and second radiating elements are formed on the dielectric substrate, have a curved shape and a size that are identical, are operable in the same frequency range, and are connected to the first and second grounding elements, respectively.