A Study of Non-contact Coupling Measurement Framework for Passive RFID Tag Antennas

• Main Authors: Wei-Jyun Li, 黎威均
• Other Authors: none
• Format: Others
• Language: zh-TW
• Published: 2012
• Online Access: http://ndltd.ncl.edu.tw/handle/18801031413559849390

碩士 === 國立雲林科技大學 === 電機工程系碩士班 === 100 === This thesis proposes a low-cost and fast non-contact coupling measurement method for evaluating the operating frequencies of passive Ultra High Frequency radio frequency identification (UHF RFID) tags during mass production. This thesis employs a self-designed excitation antenna and an in-house measurement platform to carry out the non-contact coupling measurement for RFID tags of several different frequencies. In the measurement, the RFID tag under test has to be placed near the excitation antenna that is connected to a vector network analyzer (VAN). From the measured results shown on the VNA, one can estimate the operating frequency and bandwidth of the tag under test. On the other hand, a circuit model corresponding to the power transfer between the excitation antenna and the tag was employed to characterize the coupling coefficient and the equivalent impedance of the chip-absent tag antenna. From these extracted data, the operating frequency and bandwidth of the chip-added tag for a chip with vendor-supplied input impedance can be computed accordingly. The measured results using the non-contact measurement system are found to agree reasonably well with the computed results using the above extracted data for the circuit model, and are also validated by the results measured using a commercial RFID measurement system available in Securitag Assembly Group (SAG) company. This implies that the non-contact measurement is reliable and valuable, and the circuit model is meaningful.