Design And Analysis Of The Two UHF Band RFID Antennas

With the development of society, Internet of Things (IOT) has become an inevitable trend, and the RFID technology is advancing more and more rapidly. RFID system of ultra-high frequency(UHF) band has many unique features, such as the ability to read several labels at a time, long operating distance, high speed of communication, low cost, small size, high reliability&long lifetime, endurability for harsh outdoor conditions and etc. which enables the UHF automatic remote identification technology to extend to the application fields like modern logistics, e-commerce, traffic control, e-government and military administration and others, in the national economy. Hence, the development of UHF RFID system is the focus of current RFID systems development. In the UHF RFID system, the quality of the antenna is directly related to the performance of the system, so sound design of the UHF antenna is very important and necessary.This paper first describes the market size of RFID, its practical applications as well as the status quo of RFID technical standards at home. At present, the scale of China’s RFID industry ranks third in the world; and under the promotion from the release of the first RFID national standard-the Information Technology-Radio Frequency Identification-Air Interface Protocol at800/900MHz, domestic RFID industry will achieve further development. And then the operating features of the frequency and electromagnetic waves employed by RFID are introduced. RFID uses different frequencies to meet a variety of application requirements; and the wavelength varies with different frequency of the electromagnetic waves. Then the theory of antenna and antenna technology for RFID is introduced, including antenna classification, definition, characteristic parameters and principle of radiation and etc. In the Fourth Chapter, key design points of RFID antennas are introduced theoretically, as well as the detailed design process of two UHF RFID antennas and the identification test&analysis of these two original antennas and that of their packaged forms. And at the end of the paper is the summary.The prime task of this project is the Fourth Chapter-the design process of the UHF RFID antenna. Repeated optimization and simulation was carried out to realize the matching of the antenna and the chip and to achieve sound antenna gain, which enables the chip to acquire max signal intensity through the antenna so as to operate soundly on the follow-up jobs. The matching chips for these two UHF tag antennas designed are the third generation high performance ultra-high frequency chips made by Shanghai Quanray Electronics Co., Ltd, and the model of the chip is Qstar-2A. Optimal antenna dimensions were achieved at the premises of sound impedance matching and through the respective analysis and simulation for zig-zag dipole antenna, dipole antenna of inductive coupling, dipole antenna of capacitive coupling and dipole antenna of T-type matching network-different ways for impedance matching, using AnsoftHFSS (a high frequency simulation software). After the comparison and analysis of the simulation results, zig-zag dipole antenna and dipole antenna of inductive coupling of better effects were chosen for fabrication, and the impedance test for the original antennas were taken by vector network analyzer E5071C and that of the packaged forms by testing device NI PXI RFID respectively, to prove the performance of the antennas.