A Nonlinear Transmission Line Based Harmonic RF Tag

This paper describes the design and development of a nonlinear transmission line based passive RFID tag. When the tag receives a signal from the interrogator, it generates harmonics which are transmitted back to interrogator. The reflected signal is distorted in time domain due to the harmonic contents. Hence, a change in the rise time would be observed in the received signal. Experimentally, a decrease in rise time by 14% is demonstrated using the wireless tag at a distance of 100mm from the interrogator. The tag was designed to operate in the range of 100 MHz to 500 MHz with Bragg's cutoff frequency of 1.2 GHz. This circuit will find applications in tagging, tracking and sensing.