Analysis And Design Of Microstrip Antenna For RFID Reader

Radio Frequency Identification (RFID) has been one of the most popular automatically intelligent identification technologies in the recent years, which can identify the target and exchange useful digital information via non-contact radio frequency communication between RFID readers and Tags. Compared with other identification technology, RFID has higher precision, faster identification speed and stronger ability to adapt the un-constant environments. Nowadays, UHF and microwave frequency band RFID technology develops rapidly. RFID reader antenna is a key part of the system, so it's very important to do some research on them.In this paper, the RFID Reader antenna which works in microwave S-band is analyzed, first, some basic knowledge of RFID is introduced, and the importance of the RFID reader antenna design is simply present. Then the advantages of using micro-strip patch antenna to design RFID antenna are analyzed and researched, for its advantages micro-strip patch antenna is used to design the RFID reader antenna.Second, the single patch antenna which uses in portable or hand-held reader is studied, the form of its polarization and the substrate material is discussed, after that a coaxial feed circular polarization single micro-strip patch antenna is designed for the hand-held reader, simulation results show that this antenna has excellent performance, it has good radiation direction and the half power beam width is greater than 70°, the impedance bandwidth is about 200Mhz and the circular polarization axis ratio bandwidth is about 40Mhz, the gain is around 7.5dB. The antenna's structure is simple and easy to manufacture, it's very suitable for single RFID reader antenna.Third, for the high-gain RFID reader antenna is needed more and more, the micro-strip antenna array is introduced to design the high-gain RFID reader antenna. A four circular polarization patch array is present, simulation results show that its performance is good ,the gain is about 13dB,impedance bandwidth is around 70Mhz and the circular polarization axial ratio bandwidth is about 50Mhz, half-power beam width is about 25. This antenna can be used in some special places (narrow coverage, far distance and high-gain requirement places).Finally some problems of using array antenna for RFID reader antenna are discussed in this paper.