| With the development of the radio frequency integrated circuit (RFIC), contactless radio frequency identification (RFID) technology, as one of the fastest growing sectors of automatic identification procedures (Auto-ID), gains broad application in tracking assets in supply chain management. However, one of the largest challenges for the RFID industry is that the ultra high frequency (UHF) RFID transponder doesn't function well when it is applied to any conductive surface. In this dissertation, the communication principle of wireless transceivers is illustrated. As one fast-growing application field of wireless communication, the distinct operating principle of the RFID is clarified. The factors that limit the reading/writing distance of UHF RFID transponders are discussed in detail. Some potential solutions are proposed and verified. One nondestructive solution is to apply a metamaterial such as a frequency selective surface (FSS) or a mushroom-like electromagnetic bandgap (EBG) surface to block the transmission of electromagnetic waves from the RFID antenna to the metal ground and thus boost the antenna radiation efficiency. For this solution, a new design approach suppressing the TM wave but supporting the TE wave is demonstrated. Another low-cost solution is to use an inexpensive substrate material and obtain the most power-efficient antenna structure. More than six potentially patentable planar RFID transponder antennas were invented, designed and tested. Their compact size, low profile, low cost and superior performance paves the way for the RFID industry to expand their market share in the near future. |
