Antenna device

An antenna device comprising:

• a supporting board;
• a planar first radiating plate having an electric feeding point formed on a first surface of the supporting board;
• a transmission line electrically connected to the electric feeding point formed on the first surface and extending up to one side of the supporting board;
• and
• a planar second radiating plate formed on a second surface of the supporting board,
• wherein each of the first radiating plate and the second radiating plate is formed in line symmetry with respect to a centerline of the transmission line and/or an extended line of the centerline when viewed in a thickness direction of the support board;
• a dielectric is formed respectively at both of two regions located on mutually opposite sides of the center line of the transmission line and the extended line of the center line when viewed in the thickness direction of the support board, on at least one of the first surface and the second surface;
• and
• a dielectric constant of each region is different from each other.