Design And Implementation Of Passive UHF RFID Tags

Radio Frequency Identification (RFID), which is one of the most important technologiesof Internet of Things (IoT), is developing quickly in recent years. In UHF RFID systems, theread range is the most important characteristic. For passive UHF RFID systems, the readrange is determined by the EIRP of the reader, the read sensitivity of the tag chip, the gain ofthe tag antenna and the impedance match between the tag chip and tag antenna. So, the designof the tag antennas is critical to the performance of UHF RFID systems. In this thesis, thedesign and optimization method of passive UHF RFID tag based on dipole antenna is studiedin details. And the design of a RFID embedded holographic label is proposed.First, the basic principles for RFID tag design are studied. The theory of impedancematch and the measurement of antenna impedance are analyzed in details. For passive UHFRFID tags, the antenna impedance should be the conjugate to the chip impedance to achievemaximum power transfer. The antenna impedance could be calculated by electromagneticsimulation software and measured by vector network analyzer.Second, this thesis proposes a kind of design and optimization method of small UHFRFID tag based on dipole antenna. Dipole antennas, which are simple in structure and haveexcellent performance, are widely used in UHF RFID systems. Based on the basic principle ofdipole antenna and impedance matching method, a small dipole antenna is designed andoptimization is applied in its structure. Several prototypes are fabricated and the test resultsshow that the design and optimization method is effective.At last, this thesis proposes the design of a RFID embedded holographic label, based onthe design method of UHF RFID tags mountable on metal. The metal layer in holographiclabel seriously affects the performance of common UHF RFID tags. To overcome the effect ofthe metal layer, a kind of coplanar inverted F antenna is proposed for RFID tags, and theholographic labels are pasted onto the ground of the antenna. Several prototypes arefabricated and the test results show that the designed RFID embedded holographic label has agood read range.