Patent ID: 8098211

Claim:
An antenna structure capable of implementing radio communication in two different frequency bands, a higher frequency band and a lower frequency band, the antenna structure comprising: a feed radiation electrode that is located on a surface associated with a circuit board and that functions as an antenna in accordance with a resonant operation, wherein one end of the feed radiation electrode serves as a feeding end and the other end of the feed radiation electrode serves as an open end, an electrical length from the feeding end to the open end of the feed radiation electrode is the same as an electrical length in which the feed radiation electrode performs a resonant operation at a resonant frequency set in the lower frequency band, and the feed radiation electrode has a loop shape such that the feed radiation electrode starts at the feeding end, extends in a forward direction that is directed away from the feeding end, turns around so as to extend in a backward direction that approaches the feeding end, passes through a feeding-end adjacent portion that is arranged adjacent to the feeding end with a gap therebetween, and reaches the open end, wherein the feeding-end adjacent portion and the feeding end of the feed radiation electrode are electrically connected with a shortcut path therebetween, the shortcut path being provided by a stub, wherein the stub includes a line-shaped central conductor and first and second line-shaped external conductors arranged so as to sandwich the central conductor on both sides of the central conductor with gaps therebetween, the central conductor and the external conductors are located on a board surface of the circuit board or on at least one surface of a base member provided on the circuit board, and a leading end of the central conductor and leading ends of each of the first and second external conductors are electrically connected; and wherein a rear end, which is opposite to the leading end, of the central conductor is electrically connected to the feeding end of the feed radiation electrode, and a rear end of the first and second external conductors is electrically connected to the feeding-end adjacent portion of the feed radiation electrode.