Antenna apparatus, antenna device, and impedance tuning mechanism

An impedance tuning mechanism, comprising:

• a grounding layer;
• and
• an impedance tuning layer spaced apart from the grounding layer, wherein a projection region defined by orthogonally projecting the impedance tuning layer onto the grounding layer is located inside of an outer edge of the grounding layer;
• wherein the impedance tuning layer has at least one elongated slit recessed from an outer contour thereof to a center thereof, and the impedance tuning layer has a plurality of outer slits recessed from the outer contour toward the center, and wherein the outer slits are not in contact with the center of the impedance tuning layer.

An antenna device, comprising:

• an impedance tuning mechanism comprising:
• a grounding layer;
• and
• an impedance tuning layer spaced apart from the grounding layer, wherein a projection region defined by orthogonally projecting the impedance tuning layer onto the grounding layer is located inside of an outer edge of the grounding layer, wherein a slit is recessed in the impedance tuning layer, and the impedance tuning layer has a plurality of outer slits recessed from an outer contour of the impedance tuning layer toward a center of the impedance tuning layer, and wherein the outer slits are not in contact with the center of the impedance tuning layer;
• and
• an antenna mechanism disposed on the impedance tuning mechanism and configured to be applied to a center frequency, wherein a thickness of the impedance tuning mechanism is within a range from 0.4% to 25% of a wavelength corresponding to the center frequency.