A wideband antenna includes a first radiator formed as a part of a metal frame for resonating a first signal component of a radio-frequency signal, a second radiator disposed within an area enclosed by the metal frame for resonating a second signal component of the radio-frequency signal, and a feed terminal electrically connected between the second radiator and a ground for feeding the radio-frequency signal, wherein there is a distance between the first and second radiators such that a coupling effect is induced between the first and second radiators, which allows the first signal component being fed from the second radiator into the first radiator via the coupling effect.