A Novel Reader Design for UHF Passive RFID System
Date Issued
2007
Date
2007
Author(s)
Wu, Hsin-Hung
DOI
en-US
Abstract
In this thesis, we discuss the “fading effect” in the multipath environment and explain how it influences the RFID system. Then, we propose a novel reader architecture to solve this problem. We construct a measurement system and use two separate antennas to receive the backscattered field from the tag. After some signal processes, the combining method is used to combine these two branches. Finally, we use the coherent detection method to detect the resultant signals. Through this procedure, the readability will be increased and fading effect will be combated.
In addition, when there are many tags set closely, the mutual coupling effect will make the middle tag hard to be read. Consequently, we use four different arrangements: side-by-side, cross, stagger, and corner. The spacing is 3 cm. By this method, the mutual coupling effect can be reduced, and the readability of the middle tag can be increased.
Then, in order to analyze the actual waveform received by the reader, we set three tags parallel and use vector signal analyzer (VSA) to capture the communication signals between the reader and the tag. We use the coherent detection method to detect these signals, and it can get better performance than the incoherent detection method.
Subjects
射頻辨識
衰減效應
相互耦合
同調偵測
RFID
fading effect
mutual coupling
coherent detection
Type
thesis
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