Effects of Impedance Loading on RFID Detection
Date Issued
2006
Date
2006
Author(s)
Chi-Ya-Lo
DOI
en-US
Abstract
With the increasing applications of automatic procedures, the researches on the RFID system will become more indispensable. In this thesis, the main purpose is to discuss the effects of impedance loading on a RFID system and its detection ability. We use an equation to explain the effects of impedance loading on the backscattered field, which is contributed by the residual mode component and the antenna mode component. We also discuss how to use the method of moments to calculate the backscattered field. In addition, we found that the tag scattering antenna’s properties are related to the effects of impedance loading, such as polarization, antenna gain, and antenna’s radiation pattern. In a RFID system, we use two loading values as the two states of backscatter modulation. The main purpose of RFID detection is to differentiate between the loading states. As a result, the larger the modulation level difference is, the better the detection performance is. We have found that two loadings with opposite reflection coefficients can give the maximum variation of the backscattered field. We also found that the coherent detection method can perform better than the incoherent detection method on RFID detection. If the channel of a RFID system is in a multipath environment, the signals received will suffer severe fading.
Subjects
天線形式部份
後向散射場
阻抗負載
殘餘形式部份
Antenna mode component
Backscattered field
Impedance loading
Residual mode component
Type
thesis
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