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Signal strength readout and miniaturised antenna for metal-mountable UHF RFID threshold temperature sensor tag

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Original languageEnglish
Pages (from-to)1734-1736
Number of pages3
JournalElectronics Letters
Issue number22
Publication statusPublished - 22 Oct 2015
Publication typeA1 Journal article-refereed


A new method for the wireless monitoring of a battery-free threshold temperature sensor based on a passive ultra-high-frequency radiofrequency identification (RFID) tag integrated with a bimetal thermostat switch is presented. The strategic placement of the switch brings about a strong modification in the tag antenna impedance as the temperature crosses over a threshold value. Optimisation of the narrow-band tag antenna to operate at the edges of the 902-928 MHz frequencyhopping spread spectrum RFID in the different switch states provides separate sub-bands for the readout above and below a threshold temperature. The results show that this enables an unambiguous sensor readout by monitoring the backscattered signal strength.

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