The Design Of Frequency Adaptive RFID Reader Based On The DDS Technology

Radio Frequency Identification (RFID) is one technology of automatic Identification, which is used with the radio signal to identify the items automatically and realize communication. It has many promising features such as large information capacity, long effective distance and is widely used in logistics management, traffic transportation, Industrial control and other area, etc. Now, it has been further researched about how to reduce the cost, improve efficiency and broadening the range of its application.It indicates by theory analysis and experiment result that the antenna radiation field can't maximize attainable energy when it transfers energy in the traditional RFID reader because of antenna cavity frequency disperse.Therefore, a method was systematically investigated in this paper. It is mainly researched to improve the coupling of antenna in the design of RFID system and put forward to using adaptive frequency mode based on the Direct digital synthesis (DDS) technology and searching automatically for cavity frequency. In the end, it is realized about the optimal match between RFID reader and RF card. It also eliminates the frequency error in the different readers and extends to the applications distance in the RFID system.In this paper, the analysis and design of the reader are elaborated emphatically, including the basic realized method and related hardware circuit and PCB antenna, and so on. Simultaneously, it is also described about the design of software and hardware based on test circuit concerning AD9851and MF RC500 chips.The experiment result indicates that the reader of this system has satisfied the demand of practical application and it has some characteristics such as security, reliability etc. It also provides a useful reference of the improvement RFID system.