Additively Manufactured Active FMCW Radar Imaging for Long-Range Wireless Passive Sensors

The remote measurement of physical or chemical quantities from the wireless reading of active electronic devices with integrated sensors is no more a major issue. Such devices with sensing, identification and communication capabilities can be used as nodes of a network and, more generally, part of the Internet of Things. Passive (batteryless) sensors could be used as sensing nodes in order to ensure unlimited energy autonomy, long-term measurement stability, low-cost of fabrication and operability in harsh or severe environments. However the interrogation range achievable by passive RFID sensors does not exceed 20 meters in harsh and/or highly reflective environments. An alternative solution to RFID sensors technology consists of applying an additively manufactured active millimeter-wave radar imaging technique to the detection and long-range reading of passive sensors. The first part of the talk will be devoted to the technology used by the authors and his collaborators at LAAS-CNRS, Toulouse, France, for fabricating miniaturized millimeter-wave passive sensors. Some recent sensors based on MEMS, microfluidic and/or ink-jet printing technologies will be presented. Next the active radar imaging technique will be reported for the long-range reading (up to 50 meters) of these passive millimeter-wave sensors. It consists of performing the beam scanning of the radar main lobe and/or translating the radar for illuminating the scene incorporating the sensors at different angles in order to obtain a 3D radar image. Statistical estimators are then computed from this image for remotely deriving the physical quantity of interest. Very recent results will be reported and discussed at the Workshop.