Research On Chipless RFID Tag

Radio Frequency Identification (RFID) is a contactless data-communication technique, which uses RF waves for automatic identification. With the rapid development of wireless communication in recent years, RFID technology has been more widely used. RFID technology relies on RF waves for data transmission between the RFID tag and RFID reader. So that RFID is able to fulfill automated identification and non-line-of-sight identification in comparison to other identification technologies. Because of the incomparable price advantage when compared to the price of RFID tag with microcontroller, Chipless RFID tag has a good application prospect in the field of postal, electronic ticket, retail, document tracking, then become one of the research hotspots in RFID technologies.Focusing on the Chipless RFID tag system, analyze the design of Chipless RFID tag and reader antenna, the major contribution are summarized as follows:1. A frequency and amplitude hybrid coding Chipless RFID tag is presented in this paper. Designed an open-loop resonator with stubs which has variable quality factor, by changing the orientation of gap can achieve different intensity resonant response. Using the intensity and position of resonant response as a manner to code the data, design a 12 bits Chipless tag within a surface of 25mm* 100mm and the band from 3 to 3.9GHz.2. A novel Chipless tag based on dual-polarized resonators is proposed which encodes data into spectrum by using the characteristics of resonant response. The design realizes polarization multiplexing by using crossed folded wires to make two independent resonant response in the orthogonal directions, reaches 8 bits coding capacity within a compact surface of 15mm*30mm and the band from 3 to 4.5GHz.3. A technique of adjusting the working frequency band is presented in the chapter. Place the quarter-of-wavelength slot at different position of the circular disc antenna can achieve different intensity of resonant response, so that we can adjust the impedance matching frequency band by placing slots at the specific position. Based on this technique, design two reader antennas, one cover the both band of WLAN and UWB, the other antenna with a band notch at 5-6GHz.