An antenna structure comprising: a metal frame body; a ground point; a first antenna branch coupled to a first side edge of the metal frame body, the first antenna branch comprising a first free end extending towards a middle of the metal frame body; a second antenna branch coupled to a second side edge of the metal frame body, the second antenna branch comprising a second free end extending towards the middle of the metal frame body; an antenna gap defined by the first free end and the second free end, wherein a first extension length of the first antenna branch is greater than a second extension length of the second antenna branch; and a feed point comprising a first end coupled to the ground point and a second end coupled to the first antenna branch; wherein the antenna structure further comprises: an extended antenna coupled to the first free end of the first antenna branch and separated from the second antenna branch by the antenna gap, wherein a length of the extended antenna is between one third of the extension length of the first antenna branch and one half of the extension length of the first antenna branch; the second end of the feed point is coupled to a third position on the first antenna branch, the third position is at a first length away from a connection of the first antenna branch and the metal frame body, and the first length is two thirds of a sum of the length of the extended antenna and the extension length of the first antenna branch; and a tuned circuit with one end grounded and another end coupled to a fourth position on the first antenna branch, wherein the fourth position is at a second length away from the connection of the first antenna branch and the metal frame body, and the second length is one third of the sum of the length of the extended antenna and the extension length of the first antenna branch. a metal frame body; a ground point; a first antenna branch coupled to a first side edge of the metal frame body, the first antenna branch comprising a first free end extending towards a middle of the metal frame body; a second antenna branch coupled to a second side edge of the metal frame body, the second antenna branch comprising a second free end extending towards the middle of the metal frame body; an antenna gap defined by the first free end and the second free end, wherein a first extension length of the first antenna branch is greater than a second extension length of the second antenna branch; and a feed point comprising a first end coupled to the ground point and a second end coupled to the first antenna branch; wherein the antenna structure further comprises: an extended antenna coupled to the first free end of the first antenna branch and separated from the second antenna branch by the antenna gap, wherein a length of the extended antenna is between one third of the extension length of the first antenna branch and one half of the extension length of the first antenna branch; the second end of the feed point is coupled to a third position on the first antenna branch, the third position is at a first length away from a connection of the first antenna branch and the metal frame body, and the first length is two thirds of a sum of the length of the extended antenna and the extension length of the first antenna branch; and a tuned circuit with one end grounded and another end coupled to a fourth position on the first antenna branch, wherein the fourth position is at a second length away from the connection of the first antenna branch and the metal frame body, and the second length is one third of the sum of the length of the extended antenna and the extension length of the first antenna branch. an extended antenna coupled to the first free end of the first antenna branch and separated from the second antenna branch by the antenna gap, wherein a length of the extended antenna is between one third of the extension length of the first antenna branch and one half of the extension length of the first antenna branch; the second end of the feed point is coupled to a third position on the first antenna branch, the third position is at a first length away from a connection of the first antenna branch and the metal frame body, and the first length is two thirds of a sum of the length of the extended antenna and the extension length of the first antenna branch; and a tuned circuit with one end grounded and another end coupled to a fourth position on the first antenna branch, wherein the fourth position is at a second length away from the connection of the first antenna branch and the metal frame body, and the second length is one third of the sum of the length of the extended antenna and the extension length of the first antenna branch.