Analysis of Backscattered Field of RFID Tag Antennas and Its Application in Metal-Mount Tags
Date Issued
2010
Date
2010
Author(s)
Ho, Tsung-Yen
Abstract
In this thesis, a simple method to extract the structure-mode and antenna-mode scattered fields of an antenna is proposed based on the antenna scattering formula derived by R. B. Green. The back-scattering properties of the microstrip patch antenna and the printed dipole antenna are characterized respectively using the proposed method. In addition, the physical interpretation of the antenna scattering formula is also verified. The structure-mode scattered field of an antenna depends only on its physical structure, while the antenna-mode scattered field is highly related to the radiation performance of the antenna, such as the gain. The proposed method would be of great help in the design of RFID tag antennas.
Additionally, a miniaturized patch antenna suitable for use in the metal-mount RFID tags is presented in this study. First of all, the antenna is analyzed using the Ansoft HFSS, and some parametric analyses on its impedance characteristics are performed. Given the input impedance value of a commercial RFID tag chip, the proposed antenna is properly designed to be conjugately matched to the tag chip. The back-scattering properties of the resulting antenna are then characterized using the above method. Finally, the read range of the proposed antenna is measured in the anechoic chamber. During the measurement, the antenna is integrated with a commercial RFID tag chip. For comparison, the same experimental setup is also employed to test a commercial RFID tag. The results show that the reading performance of the proposed antenna is not affected by the presence of the metallic object. Therefore, the proposed antenna may be used in the metal-mount RFID tags.
Subjects
RFID
Tag antenna
Backscattering
Structure mode
Antenna mode
Type
thesis
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