Patent ID: 8279133

Claim:
An antenna device comprising: an antenna element; and a printed circuit board on which the antenna element is mounted, wherein the antenna element includes: a base that is made of dielectric material and has substantially rectangular parallelepiped shape, said base includes a bottom surface and an opposing upper surface, the bottom surface facing the printed circuit board; an inductance adjustment pattern that is formed on the upper surface and a side surface of the base and has a substantially U-shape; a capacitance adjustment pattern that is formed on the upper surface of the base and is placed to face the inductance adjustment pattern via a gap with a predetermined width; first and second terminal electrodes that are provided at one end of the bottom surface of the base in a longitudinal direction of the base; and a third terminal electrode that is provided at the other end of the bottom surface in the longitudinal direction of the base, the printed circuit board includes: an insulating substrate; an antenna mounting region that is a substantially rectangular insulating region provided on a surface of the insulating substrate in contact with an edge of a side of the insulating substrate; a ground pattern that is formed on a surface of the insulating substrate so as to define three sides of the antenna mounting region excluding the side having the edge; a feed line that is led into the antenna mounting region along the edge; first to third lands that correspond to the first to third terminal electrodes, and are provided in the antenna mounting region; and a ground clearance region that is free of the inductance adjustment pattern, the capacitance adjustment pattern, and the ground pattern, and is formed on a bottom surface and an inner layer of the insulating substrate located immediately below the antenna mounting region, the antenna element is installed between a first side and a second side of the ground pattern that form two facing sides of the antenna mounting region, one end of the inductance adjustment pattern is connected to the feed line via the first terminal electrode and the first land, the other end of the inductance adjustment pattern is connected to the first side of the ground pattern on the side of the feed line via the second terminal electrode and the second land, wherein the first terminal electrode is closer to the edge than the second terminal electrode, and the third terminal electrode is connected to the second side of the ground pattern.