Design and demonstration of passive UWB RFIDs: Chipless versus chip solutions

This paper reviews recent research on Ultra-Wideband (UWB) techniques for the next generation Radio Frequency IDentification (RFID) towards the Internet-of-Things (IoT), conducted by Vinn iPack Center at KTH, Sweden. First, we introduce an inkjet printed chipless UWB RFID for ultra-low cost applications such as item-level tracking. The identification number is coded by variations of the impedance over the transmission line, resulting in the OOK modulated data by means of pulse reflections in time domain. Prototypes were fabricated and measured for 4-bit tag and 8-bit tag, respectively. Thanks to the employment of fully printing process and paper substrates, the tag is potentially ultra-low cost in volume production. Second, a wirelessly powered RFID tag with an active UWB transmitter is studied for advanced applications such as wireless positioning and sensing. The tag is powered by UHF continuous waves, whereas it uses an UWB pulse generator to transmit data to the reader. It ensures the improved coverage and accurate positioning over traditional backscattering UHF tags. UWB readers, positioning, and sensing are also discussed in a system perspective. The two solutions reveal that UWB is a viable alternative to existing passive RFIDs adapting both low-cost applications and high-performance sensing and positioning applications.