UHF RFID Reader Antenna Design Technology Research

Radio frequency identification (RFID) is a non-contact automatic identification technology, as compared with other means of identification, the technology has a high identification accuracy, speed, environmental adaptability, etc., in recent years has developed rapidly. RFID reader antenna is a key part of the RFID system, so its research and design have become hot in recent years. This paper, based on RFID technology used in the Electronic Toll Collection System (ETC), made a particular reader antenna research and design.This paper, starting with theoretical analysis, first introducing the basic principles of RFID technology, focusing on the RFID reader and the microstrip antenna as the RFID reader antenna has advantages. After making a more detailed study of the microstrip antenna related theories, including the definition of microstrip antennas, the typical structure, radiation theory and analysis methods.Then, this paper, based on theoretical analysis of circularly polarized microstrip antennas, designs a UHF RFID reader orthogonal-fed antenna, which uses 3dB branch coupler to feed rectangular microstrip antenna, thus motivating two equal amplitude and phase difference of 90°of the degenerate mode, consequently make the antenna produce circular polarization waves. After using ADS to simulate and optimize the antenna, its performance meets the design requirements.Finally, this paper, based on the analysis of a single-fed circularly polarized microstrip antenna theory, designs a new type of single-fed ultra-high frequency RFID reader antenna, which uses relative to the current widespread adoption of symmetrical isosceles triangle Cutaway easier processing of non-symmetric rectangular cutting angle to achieve the circular polarization, and through the coax to the antenna feed. Compared with the orthogonal-fed antenna, the antenna does not require a complex feed network to realize easy, simple process. As the deviations between the theoretical design and actual simulation, this paper makes further studies on its performance impact of antenna parameters, followed by the use of research results optimizing the antenna. The optimized antenna with good performance meet the ETC system on the RFID reader antenna requirements.