Multi-path interference reduction in passive NLTL RFID tags

We propose a multi-path interference reduction method of continuous wave (CW) passive RFID for indoor ranging applications by adopting nonlinear transmission line (NLTL) tags. Because the power and phase information are contained within the second harmonic (SH) rather than the fundamental frequency, interference and phase errors caused by direct reflections of interrogating signal can be greatly reduced. We present both theoretical predictions and simulations, followed by experimental results to verify the effectiveness of the proposed approach.