Passive UHF RFID Tag Antennas-Based Sensing for Internet of Things Paradigm

Recently, the ultra-high frequency (UHF) radiofrequency identification (RFID) technology has progressed rapidly from simple labeling and identification to flexible and scalable sensing technology that opens the paradigm of Internet of Things (IoT) paradigm. The sensitivity of UHF tags from the perspective of labeling, tagging, and identification is considered to be a major limitation. However, this considerable weakness can be exploited to transform UHF RFID tags into low-cost, more attractive, and wireless pervasive sensors. The communication channel parameters such as backscatter received signal strength (RSSI) and RF phase are used as sensing metrics for sensing environments effects and user activities. Moreover, machine learning and signal processing techniques are used to add more enthralment and accuracy in UHF RFID-based sensing. Therefore, this chapter aims to provide an overview of sensing parameters, techniques, state-of-the-art passive UHF RFID sensors design IoT-based solutions, their applications in daily life environments, commercial tag solutions, and use of machine learning algorithms to improve sensor data accuracy.