Analysis Of UHF RFID Tag Antenna For Robustness

Radio frequency identification (RFID) is a rapidly developing technology which uses RF signals for automatic identification of objects. RFID system has been widely used in many areas, so the working environment is complicated and the types of target object are diverse. However, the tags always work in some specific environment, and they are very sensitive to the working environment, especially the UHF RFID tag antennas, which may result in that the tag can’t be working regularly. To overcome the environment’s influence, in this paper, I will research and design the UHF RFID robust tag antenna which can be applied to identify many various objects.The referred robust tag antenna mentioned in the related literature is mainly the microstrip antenna or the chipless antenna, but these existing antenna in the practical application has some restrict and shortcomings. So a new type of antenna is proposed in this paper, the proposed tag antenna works as a dipole in the free space, and when attached on the metal surface, has a good performance as a microstrip antenna using the metallic object surface as its ground plane, and I also do some design of the antenna to realize the antenna miniaturization. The innovative point of the proposed tag antenna is that it can work in two different cases with the same structure, but the shortcomings of the proposed antenna is that it can’t be working in the environment which containing water or some other liquid, so another robust RFID tag antenna composed by a dipole antenna and an electromagnetic radiation decoupler with significant advantages for the detection of metal and liquid is proposed in this paper, the dipole antenna can work in the free space or placed on some dielectric objects such as paper, glass and foam, and when attached on the metal surface, has a good performance combined with the decoupler, which can be a layer between the dipole tag and the metal objects surface. The second proposed tag antenna has a very flexible application and it shows the better robustness.In this paper, I do a lot of simulation and optimization for the proposed two tag antennas with HFSS. The experiment was carried out on the fabricated robust tag antennas get their impedance, both the simulation and experimental results match well. In addition, we measured the tag sensitivity and reading distance of the fabricated tags in an anechoic chamber in different cases, using a commercial measurement system, Tagformance Lite and the experimental results show that the tag antennas have a good reading distance. All the actual measurement results show that the proposed two tag antenna can work to identify different target objects with good robust characteristic.