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Publication type: Conference paper
Type of review: Peer review (abstract)
Title: Adaptive carrier supression for UHF RFID using digitally tunable capacitors
Authors: Küng, Roland
Koller, Marcel
DOI: 10.21256/zhaw-3333
Proceedings: Proceedings of the 43rd European Microwave Conference
Conference details: 2013 European Microwave Conference, Nuremberg, Germany, 6-10 October 2013
Issue Date: 2013
Publisher / Ed. Institution: IEEE
ISBN: 978-2-87487-031-6
Language: English
Subjects: RFID; Reader; UHF; Suppression
Subject (DDC): 004: Computer science
Abstract: In UHF (Ultra High Frequency) RFID (Radio Frequency Identification) systems Rx (Receiver) is usually isolated from Tx (Transmitter) by a circulator or a directional coupler. Since tags become more sensitive in order to improve reading distance, the relatively poor isolation of 20dB – 30dB limits the tag to reader link. A way to improve a directional coupler’s isolation is to mismatch the unused port to generate a carrier cancelling signal. In this paper an impedance network using digitally tunable capacitors is proposed. The advantage of this solution is that changes in the system – like antenna characteristics or cable length - can be recalibrated at any time by a controller. Finally an isolation of minimum 47dB for any antenna characteristic (minimum return loss of 18dB) and any cable length was reached. Also an algorithm was implemented on a simple MSP430 controller to find the optimum impedance to minimize carrier leakage.
Fulltext version: Accepted version
License (according to publishing contract): Licence according to publishing contract
Departement: School of Engineering
Organisational Unit: Institute for Signal Processing and Wireless Communications (ISC)
Appears in collections:Publikationen School of Engineering

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