The Effect of Curvature on the Performance and Readability of Passive UHF RFID Tags
D. D. Arumugam, D. W. Engels, M. H. Mickle
In this paper, the effect of curvature on the passive UHF RFID tag is studied. Maxwell’s equations are used to depict the typical curved passive tag and are used to study the theoretical limitations of a tag operating under curvatures at its normal axes. This theoretical framework is then used to analyze the typical tag for various curvatures. Here, the analysis is conducted to derive the effect of curvature on the optimal impedances for ASIC load matching, as well as gain. This analytical evaluation is also generalized to describe the shift in center frequency of the tag operation due to tag curvatures. The results derived from this theoretical study on commercially available passive UHF RFID tags are verified with experimental results. It is shown that the curvature of passive UHF RFID tags have a significant impact on the performance and readability at values of K > pi/lambda, and reaches a breakdown on conformity at curvature values of K = 4pi/lambda.
ACES Journal
2010
March
25
3
206 - 217
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