Patent ID: 7561112

Claim:
A composite antenna device comprising: a ground board; an unbalanced antenna including a first feeding point electrically coupled with the ground board, a first radiator having a first end and a second end, the first end of the first radiator being connected with the first feeding point, and a load conductor having a first end, a second end, and a connection point where the load conductor is connected with the second end of the first radiator, the load conductor intersects a straight line which also passes through the first feeding point and which is perpendicular to the ground board; a balanced antenna including a second feeding point electrically isolated from the first feeding point, a second radiator connected with the second feeding point, and a third radiator connected with the second feeding point, wherein the load conductor of the unbalanced antenna includes a first portion and a second portion, the first portion of the load conductor being provided between the first end of the load conductor and the connection point, the second portion being provided between the second end of the load conductor and the connection point, and wherein an impedance Z 11 of the first portion of the load conductor, a mutual impedance Z 12 of the second radiator to the first portion of the load conductor, a mutual impedance Z 21 of the first portion of the load conductor to the second radiator, an impedance Z 22 of the second radiator, an impedance Z 33 of the second portion of the load conductor, a mutual impedance Z 34 of the third radiator to the second portion of the load conductor, a mutual impedance Z 43 of the second portion of the load conductor to the third radiator, and an impedance Z 44 of the third radiator satisfy the relation of ( Z ⁢ ⁢ 11 Z ⁢ ⁢ 12 Z ⁢ ⁢ 21 Z ⁢ ⁢ 22 ) = ( Z ⁢ ⁢ 33 Z ⁢ ⁢ 34 Z ⁢ ⁢ 43 Z ⁢ ⁢ 44 ) .