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| Author: | Gao, Xinwei |
| Title: | Operation of Coupled RFID Tags |
| Publication type: | Master's thesis |
| Publication year: | 2015 |
| Pages: | vi + 48 Language: eng |
| Department/School: | Sähkötekniikan korkeakoulu |
| Main subject: | Radio Science and Engineering (S3012) |
| Supervisor: | Viikari, Ville |
| Instructor: | Holopainen, Jari |
| Electronic version URL: | http://urn.fi/URN:NBN:fi:aalto-201505192752 |
| Location: | P1 Ark Aalto 2843 | Archive |
| Keywords: | RFID coupling chip model operation impedance |
| Abstract (eng): | A typical RFID system works in the way that one RFID reader can interrogate one or more RFID tags. However, some lab experiments found tags' strange behavior when one reader is interrogating a bunch of identical coupled tags. During the interrogation process, when the transmitted power from the reader is continuously increasing, some tags first operate normally but suddenly stop responding at some moment. This is very likely due to the tag's chip failing to absorb the minimum threshold power to support tag operation at that moment. One possible explanation for this behavior is the combined effects of coupling between tag antennas and chip's inherent nonlinear impedance. The objective of this thesis is to test whether this hypothesis is correct or not. In order to reach the target, the main tasks in this thesis are to design appropriate antennas and model chip's nonlinear impedance. First, the appropriate antennas are designed and simulated in the EM simulator where coupling between antennas can be obtained in the form of S-parameters. Second, the chip model whose impedance varies with its absorbed power can be realized in the circuit simulator. Finally, the interrogation process between the reader and tags can be simulated with the chip model and S-parameters in the circuit simulator. Through monitoring the chip's absorbed power with the increasing transmitted power in the simulation, it is possible to find out whether the chip may stop operation during the process. According to the final simulation results, in some cases, when the transmitted power is continuously increasing, the status of chip's absorbed power is such that it increases in the beginning but begin to decrease at some point. Moreover, in some certain case, the chip's absorbed power even goes down to a level that is lower than the chip's minimum threshold power. Hence, the hypothesis is proved to be trustful and the target of this thesis is fulfilled. |
| ED: | 2015-05-24 |
INSSI record number: 51303
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