Patent ID: 7825810
Filing Date: 2010-11-02
Classification: G06K

Abstract:
1. A RFID tag read system for reading predetermined data from a RFID tag, said RFID tag radiating an answer wave as an electromagnetic wave when said RFID tag receives a question wave as an electromagnetic wave, said answer wave including said predetermined data, said RFID tag read system, comprising: a read device for outputting said question wave as a high-frequency current, and reading said predetermined data by demodulating said answer wave when said answer wave is inputted therein as a high-frequency current, an antenna system including first to third antennas for outputting said high-frequency current when said first to third antennas receive said electromagnetic wave, and radiating said electromagnetic wave when said high-frequency current is inputted therein, wherein said first antenna is connected to said read device via a first feeder wire, said second antenna is located such that radiation direction of said second antenna is made parallel and opposite to radiation direction of said first antenna, said third antenna is connected to said second antenna via a second feeder wire, each of said first, second and third antennas is an unidirectional antenna, and a fourth antenna for outputting said high-frequency current when said fourth antenna receives said electromagnetic wave, and radiating said electromagnetic wave when said high-fre-quency current is inputted therein, said fourth antenna being located such that radiation direction of said fourth antenna is made parallel and opposite to radiation direction of said third antenna, and further comprising either of: a first wave director for sharpening directivity of said electromagnetic waves by changing phases of said electromagnetic waves, said electromagnetic waves being transmitted/received by said first antenna and said second antenna, and a second wave director for sharpening directivity of said electromagnetic waves by changing phases of said electromagnetic waves, said electromagnetic waves being transmitted/received by said third antenna and said fourth antenna.