US Patent 12009609 Antenna device

An antenna device includes: a ground plate made of a conductor with a flat plate shape; an opposing conductive plate made of another conductor with a flat plate shape, arranged to space apart from the ground plate by a predetermined distance, and having a power supply point electrically connected to a power supply line; a short-circuit portion electrically connecting the opposing conductive plate and the ground plate; and a radio wave shield body for shielding a propagation of an electric field, which is arranged on an upper side of the opposing conductive plate and is made of a conductor or a dielectric material. Parallel resonance at a predetermined target frequency is generated by an inductance provided in the short-circuit portion and a capacitance between the ground plate and the opposing conductive plate.