The Design Of Long Distance RFID Reader

Radio Frequency Identification (RFID) is one technology of Automatic Identification, which is used with alternative magnetic filed to realize contactless communication. In the last several years, the applied field of RFID technology has been extended surprisingly.The paper has designed one RFID Reader for TAGIT tag and I-CODE1 tag. The design of hardware include design of RF ReadAVrite module, design of MCU circuit, design of serial communication circuit, design of RF power amplifier (PA), design of RF signal processing circuit and antenna design. During those parts, the design of RF PA and antenna design are key parts. The PA circuit was able to amplify two signals with different type of modulation ASK and FSK. Both TAGIT tag and I-CODE1 tag are passive tags. Not only the antenna of reader has to send/receive RF signals, but also has to supply the power for tags. Based on the principal of transformer, one antenna was designed. The reader realized the function of using one antenna to send and receive RF signals. As for the signal received by the antenna, demodulator was designed to demodulate the signal modulated by subcarrier. To satisfy the RF RAV module's demands for input signal's strength and modulation depth, the signals modulated by the subcarrier was modulated to carrier of 13.56MHz. The design of software realized the function of controlling the RF RAV module to operate with the tags.The reader realized the function of operating with both TAGIT tag and I-CODE1 tag. The operating distance was about 70cm. The stability of the reader was proved by the actual applications.