Research And Design On UHF Anti-Mental RFID Tag Antennas

With the continuous development of commodity economy, the demand for electronic tags isgrowing rapidly. The performance of common dipole tag antennas tend to be greatly affected whenthey work on the metallic surface. It is mainly researched in this paper about how to design tagantennas that can work well in both free space and metallic environment is mainly researched.The microstrip antennas can work well on metallic surface since there is a metal ground planeon the bottom. Three different tag antenna designed in paper all have the structure of metal ground.It is confirmed that the antennas can work well when placed on metallic surface after simulation andmeasurement.The chips used in this thesis are named UHF Gen2STRAP of RI-UHF-STRAP-08series andthe reader supplied in the laboratory is named ALR-9611-CR.An inserted fed type microstrip tag antenna is designed at the beginning. The tag antenna hasthe structure of a conventional microstrip antenna. And the radiation part is connected to groundthrough a shorting cross-section. The magnitude of input impedance of the antenna is reduced bythe inserted fed structure.The impedance band width of the antenna is over40MHz, which coversthe working frequency band of the reader. And the maximum gain achieves-1.9dBi when placed onthe metal surface.The other antennas have no cross-section, which is an advantage compared to the microstripantenna. And this makes it easy to fabricate. The second antenna has a new structure. The radiationparts are two large rectangular metal patches and between them are the matching network and thepads for the chip. The band width of the antenna is over40MHz, which covers the workingfrequency band of the reader. And the maximum gain achieves-2.5dBi when placed on the metalsurface. The other is a ring-shaped tag antenna. The radiation part of the antenna is the ring and in itare the matching network and the pads for the chip. The band width of the antenna is over50MHz,which covers the working frequency band of the reader. And the maximum gain achieves1.2dBiwhen placed on the metal surface.