On RFID Multi-Frequency Antenna And Antenna Array

Radio frequency identification (RFID) technology has been increasingly concerned as one of the key technology with the raid development of the internet of things (IoT) science. As a key component of RFID system, antenna plays an important role in determining the system performance. So far, Research on the RFID antenna mostly focuses on the tag antenna. Compared to the mature research results on low frequency and high frequency band, meanwhile, because of the fundamental difference of the design principle, the research on RFID tag antenna in ultra high frequency (UHF) and microwave band need further exploration. At present, the environmental factors which affect antenna performance and the structure size of the antenna is the main research content of the RFID tag at home and abroad. What’s more, the structure size affects the multi frequency and broadband characteristics.The main research in this paper is on multi frequency characteristics study and performance index enhancing of tag antenna, impedance matching is included. In terms of numerous advantages of microstrip antenna such as light weight, thin profile, small size, much study in this paper is based on microstrip antenna. Two models of RFID dual frequency microstrip antenna in microwave frequency band, which achieve1.9GHz/2.45GHz and2.45GHz/5.32GHz working frequency, is designed in this paper. The coaxial feed and coplanar waveguide feed is used in each model. These two models both meet the standards IEEE802.11b/g and IEEE802.11a and their maximum gain is3.9dBi, which14.7%-26%higher than the printed antenna designed under the same frequency band. What’s more, the test results in the parameters of the antenna under the different media interference are showed out. Besides, this paper introduces the design idea of antenna array in order to improve the antenna gain and read-write distance. A1×4element uniform linear array is designed with the maximum gain up to8.55dBi. In terms of the impedance matching, the equal power transmission model for single antenna and antenna matching network model for antenna array are proposed. Furthermore, the mutual coupling of antenna array is discussed in this paper and the modified mutual coupling compensation model is present.