Patent ID: 8242913

Claim:
An RFID tag communication apparatus comprising: a housing constituting an equipment shell including a bottom surface fixed in contact with a predetermined installation surface; an antenna provided at a distance h ranging from h 1 to h 2 from said bottom surface that transmits and receives information by wireless communication with an RFID tag including an IC circuit part that stores information and a tag antenna that transmits and receives information; and a radio frequency circuit including a carrier wave transmitting device that generates a carrier wave of a frequency fc for supplying power to said RFID tag, that transmits and receives information with said RFID tag; the frequency fc is set within a range of fo<fc<fm, in accordance with setting of the separation distance h, ranging from h 1 to h 2 , of the antenna from said bottom surface, under the conditions that fm is set for a resonance frequency of said antenna when said bottom surface is fixed in contact with said installation surface made of a metal, and fo is set for a resonance frequency of said antenna when said bottom surface is fixed in contact with said installation surface made of a non-metal or said bottom surface is separated from said installation surface resulting in a single unit state of said RFID tag communication apparatus, wherein: the frequency fc and the distance h are set to satisfy the correlation as: fc=(fo+fm)/2.