Classification of Radar Echoes for Identification and Remote Reading of Chipless Millimeter-Wave Sensors

This article describes the wireless and simultaneous interrogation and identification of multiple passive (zero-power) pressure sensors in an industrial environment with a reading range of at least 4 m. The 3-D beamscanning of the scene is performed from a 24-GHz frequency-modulated continuous-wave (FM-CW) radar and for diverse electric field polarizations. The identification is performed using a k-nearest neighbor classification. The benefit of using the cross-polarized electric fields combined with a radar imagery technique is enlightened from the analysis of the background clutter and the simultaneous remote interrogation of several passive pressure sensors at a distance up to 17.7 m. The measurement uncertainty on pressure obtained from the proposed long-range wireless technique is finally reported and discussed.