Patent ID: 8866693

Claim:
An antenna device comprising: an antenna board comprising: a dielectric plate having a first surface and a second surface; an antenna pattern in or on the first surface of the dielectric plate; and a ground layer formed in or on the second surface of the dielectric plate; a metallic plate disposed facing the ground layer of the antenna board; and a plurality of metallic spacers connecting the ground layer of the antenna board to the metallic plate, wherein a feed pin is disposed through the ground layer and the dielectric plate to feed electric power or a signal to the antenna pattern; wherein the metallic plate and the ground layer are coupled and electrically connected through the plurality of metallic spacers; wherein a first conductor pattern is formed in a predetermined area including a connection point to the feed pin while separated from the ground layer in the ground-layer forming surface of the antenna board, a second conductor pattern is formed near the first conductor pattern while separated from first conductor pattern and the ground layer, wherein the first and second conductor patterns are connected in series through a capacitor; and wherein a coaxial cable is inserted in a gap between the antenna board and the metallic plate, and an inner conductor of the coaxial cable is connected to the second conductor pattern while an outer conductor of the coaxial cable is connected to the ground layer.