Development of Environmental Long Range RFID Sensors Based on the Modulated Scattering Technique

This work presents the development of a wireless sensor system for environmental monitoring based on the modulated scattering technique (MST). The MST sensor probes are based on the scattering properties of small passive antennas and radiate part of the impinging electromagnetic field generated by an interrogating antenna, which also acquires the backscattered signal as information. The MST probes are able to deliver data without radio frequency front end. They use a simple circuit that alternatively terminates the antenna probe on suitable loads to generate a low modulation signal on the backscattered electromagnetic wave. In this work, the MST sensor system for environmental monitoring has been proposed to obtain the best performance in communication range, load efficiency and power harvesting. The MST sensor has been fabricated and assessed in practical scenarios. The proposed prototype, able to operate in X band at 10 GHz and able to provide a communication range of about 15 m, serves as a proof-of-concept. The acquired measurements demonstrate that the prototype is able to measure accurately and send data without radio frequency front end or bulky wired connection with the same efficiency of standard wireless sensors such as radio frequency identifier (RFID) or wireless sensor networks (WSN)