Time-Domain UWB RFID Tag Based on Reflection Amplifier

This letter describes an active ultrawideband (UWB) tag for radio frequency identification (RFID) and wireless sensor applications. The tag is composed by a UWB antenna connected to a one-port reflection amplifier. A UWB impulse radar is used as the reader. The reader sends a short pulse, and its echo is amplified and reflected back due to the return gain of the tag amplifier. The amplitude of the reflected pulse is modulated by controlling the amplifier bias. The basic theory of ultrawideband operation applied to the time-domain RFID system is described. Experimental results with a proof-of-concept tag using commercial components are presented.