Antenna device and method of manufacturing the same

A method of manufacturing an antenna device, the method comprising:

• forming a first coil conductor on a base layer, the first coil conductor including a first large-diameter loop shaped conductor and a first small-diameter loop shaped conductor connected to a first end of the first large-diameter loop shaped conductor, wherein the first large-diameter loop shaped conductor has a larger diameter than the first small-diameter loop shaped conductor and the first large-diameter loop shaped conductor and the first small-diameter loop shaped conductor each comprise a single winding;
• punching a metal plate to form a second coil conductor including a second large-diameter loop shaped conductor and a second small-diameter loop shaped conductor connected to a first end of the second large-diameter loop shaped conductor, wherein the second large-diameter loop shaped conductor has a larger diameter than the second small-diameter loop shaped conductor;
• fixing the second coil conductor to the first coil conductor with an insulating adhesive layer interposed between the first coil conductor and the second coil conductor, such that the first large-diameter loop shaped conductor opposes the second large-diameter loop shaped conductor and the first small-diameter loop shaped conductor opposes the second small-diameter loop shaped conductor;
• and
• disposing a power supply coil connected to an RFIC element on the base layer within an opening of the first small-diameter loop shaped conductor and a coil opening of the second small-diameter loop shaped conductor.