Research Of RFID Antenna For High Speed Object Identification

RFID (Radio Frequency Identification) is a sort of automatic identification technique which is advancing owing to the development of the large scale integrated circuit. The security of RFID technique is very high, and the environment adaptability is good. The influence of rain, snow, hail or dust on the RFID system is quit week, and it can operate in all weather. RFID system can wirelessly complete the automatic identification, tracking and management, therefore it has extensive application in the identification of high speed motional object. As the most important advantage of RFID system is non-contact identification, thus the key component is the antenna, which is performed as emit or receive device to realize data communication between the tag and the reader.Above all, the study status and trends in development of RFID antenna are summarized in this thesis. The basic composition and operational principle of RFID system are discussed systematically as well as the division of the fields of antenna and the coupled modes of energy capacity. And the operating frequency and typical application of RFID are investigated to determine basic antenna structure. RFID antennas we research operate at 915MHz, which belong to VHF, therefore microstrip patch antenna is adopted as base station antenna and various balanced dipole antennas are employed as tag antennas. Then, a brief introduction is given on the radiating principles of the microstrip antenna. Based on the theory of microstrip antenna, a feasible structure of the antenna is analyzed. After that, the general structures and design parameter of microstrip patch antennas are described, and methods to enhance the bandwidth are also discussed. The microstrip patch antennas are simulated and analyzed based on numerical method and optimal results are achieved. Antennas are feed by 50ohm coaxial cable and feed networks are unnecessary. And then, tag antennas are analyzed and designed, which include plate balanced dipole antenna, triangle balanced dipole antenna and inductively coupled feed meander-line antenna. Theory analysis and simulations are given and optimal results are achieved. Finally, the experimental samples are manufactured according to the design parameters. The experiment samples are tested and measured data is obtained.