Short Range Propagation Characteristics of UHF Frequency Band for Moving Vehicles RFID

摘要

In this paper, we describe the short range propagation characteristic of UHF RFID frequency band used for moving vehicles. To analyze the propagation characteristic of UHF RFID radio signals in short range radio propagation environment, we transmitted 910 MHz and 2.45 GHz continuous wave carrier signals using by several polarized antenna combinations. From the measurement analysis, it can be clearly seen that the UHF RFID signal can be encountered to multipath interference rays due to ground plane and the reader/antenna equipment booth. In addition, it was found that the multipath interference signals can be effectively removed by using a circularly polarized antenna. Especially, in case of NLOS environment, it was also found that circular polarization diversity method using the two branches of vertical and horizontal receiving antenna shows better fading reduction effect.