Passive UHF (Ultra High Frequency) RFID (Radio Frequency Identification) is a promising technology for products tracking in logistics or routing packages in supply chain. However, passive UHF RFID tag suffers a lot when it is placed on conductive plane or water surface. Many designs like microstrip antenna and ferrite antenna have been used to solve this metal-water problem. But their use is limited by narrow bandwidth and low antenna gain. The Electromagnetic band gap (EBG) material which exhibits a unique forbidden band gap at certain frequency offers a potential solution to solve the problem of backside objects effects. In this thesis, we disclosed a new method using mushroom-like electromagnetic band gap (EBG) material to insulate the UHF RFID tag from backside objects, so that the...[ Read more ]

Passive UHF (Ultra High Frequency) RFID (Radio Frequency Identification) is a promising technology for products tracking in logistics or routing packages in supply chain. However, passive UHF RFID tag suffers a lot when it is placed on conductive plane or water surface. Many designs like microstrip antenna and ferrite antenna have been used to solve this metal-water problem. But their use is limited by narrow bandwidth and low antenna gain. The Electromagnetic band gap (EBG) material which exhibits a unique forbidden band gap at certain frequency offers a potential solution to solve the problem of backside objects effects. In this thesis, we disclosed a new method using mushroom-like electromagnetic band gap (EBG) material to insulate the UHF RFID tag from backside objects, so that the tag could work on water surface and even metal. The design of EBG material for UHF RFID which operates at 915 MHz was discussed in this thesis. An EBG tag on metal with a gain of 4 dBi was achieved in simulation and a prototype of 4.3 mm thick RFID on metal tag was measured in experiment. The simulation results showed that the RFID tag still could be read on EBG substrate with a good gain (~4dBi). The measurement results indicated that the read rang of RFID tag with EBG substrate could reach up to 4.5 meters on metal template.