A Passive Harmonic Reradiator Tag for Animal Tracking

摘要

Low power sensor nodes distributed over a large geographical area provide an economical way to collect envi-ronmental information. The sensors can utilize backscatter signals to communicate with a central node withoutsignificant power consumption. Each sensor can modulate its reflected backscatter signal by switching a load onthe sensor antenna. This allows design of low power sensor nodes with longer lasting battery life. The nodes canbe built to reradiate a harmonic of the received signal. This helps to avoid interference at the central node fromreflection from unwanted objects. A passive harmonic reradiator is designed in this project to receive a 915 MHz electromagnetic wave andreradiate at 1.83 GHz. The design consists of receiver antenna, transmitter antenna, a Schottky diode, andmatching network. Simulation and measurement results are provided. The results show promising characteristicsfor the use of the device to track animals in wild life.