High frequency package device with internal space having a resonant frequency offset from frequency used

A high frequency package device, comprising:

• a bottom plate;
• a plurality of side walls provided on the bottom plate to surround a space above the bottom plate;
• a lid to close an opening formed by the plurality of side walls and to form an internal space on the bottom plate together with the plurality of side walls;
• a dielectric plate arranged on the bottom plate in the internal space, having a smaller width than an inner surface of the lid;
• an input line to penetrate a first one of the plurality of side walls;
• an output line to penetrate a second one of the plurality of sidewalls;
• and
• a projection provided on the inner surface of the lid to form a region facing the dielectric plate and to have a surface area, facing the dielectric plate, where a distance between the projection and the bottom plate where the projection is provided is shorter than a distance between the lid and the bottom plate where the projection is not provided, the lid and the projection coupled to pass a current therebetween, wherein the inner surface of the lid extends further toward an inner surface of one of the plurality of side walls than does the projection extend to the inner surface of the one of the plurality of side walls, wherein the bottom plate, the plurality of side walls, the lid, and the projection are composed of metal material, and the lid and the projection are composed of the same metal material.