Study Of RFID Reader In UHF Band

As an automatic identification technique without touching, radio-frequency identification (RFID) technology use radio waves carrying information stored about the identified object or commands to identify objects via space coupling. Compared with other identification technologies, RFID technology used for identification has many advantages. Thanks to the rapid development of electronic techniques and manufacturing technology, the RFID applications based on the wireless and radar techniques emerge rapidly, which will be found very useful in many fields, and has the huge development and potential. As a vital and integral part of RFID system, RFID reader has received much attention, and their design is very urgent and significant, the research and development of RFID reader is of practical value for the RFID system.According to the Type B protocol of ISO 18000-6, the reader of RFID system for the UHF frequency was researched and designed on the foundation of a detailed analysis on the relative theory and technology for UHF RFID. Firstly, fundamental technology of the whole RFID system is expatiated, detailed depiction from the two sides of electromagnetism and communications science. Moreover, the basic principles of the system and its various components be introduced and analyzed, and on this basis to meet the actual requirements of design, and systemic plan also be made. The interference of transmitting and receive channel issue is analyzed and research, and then a novel technology based on RPC is proposed to improve the isolation between TX and RX. By thoroughly discussing the reader's receiving method, zero-IF directly receiving technique with four channels are proposed to increase the sensitivity of reader, eliminate the existence of ambiguity points, and besides, specific circuits are designed for all parts of the reader, which are then produced and debugged. In addition, the antenna array design of the RFID reader is investigated. Via a lot of tests and experiments, the VSWR of this antenna array is below 1.4 and gain is 16dB approximately in 860-960MHz.