The wireless measurement of Section (RCS) variability of p the authors and their collabor 2010. A millimeter-wave (m RADAR was used for the mea physical quantity changes. Th multi-beam or beam-steering sequentially in many directio variability measurement has physical quantities, such as applications using MEMS tec RCS-variability measurement detection, identification and re will be discussed. These imag For illustration purpose Figu passive sensors obtained from used mechanical beam-steer transmitting RADAR antenna scanning system was advantag remote reading of passive ele discussed at the conference. proposed wireless interrogatio (a) Figure 1: RADAR im (a) 2D visualization in a given given threshold (measuremen structural scattering mode o Meters Meters f a physical quantity from the analysis of t passive (battery-less) sensors was proposed f rators in 2008 while the proof-of-concept w mm-wave) Frequency-Modulated Continuou asurement of RCS variation and for the remo he choice of mm-wave frequency range facil FMCW RADAR for interrogating sensors ons in space. The wireless sensing techniq been successfully applied to the remote e s temperature (2010-2012) and strain (20 chnology of the proposed wireless sensing t t will be presented at the conference. Mor eading of such sensors from the analysis of 3 ges were obtained by using a beam-steering ure 1 shows RADAR images of a scanned m a 24GHz FMCW RADAR (bandwidth: 2G ring in elevation and in azimuth. The m a was performed by computer. Such automa geously used by the authors for the detection ectromagnetic sensors. Very recent results w The technical challenges and possible solu on of passive EM sensors will be presented. (b) mages of a scanned region containing passive n cut-plane and (b) 3D visualization of echo l nt results). The circles indicate the EM echo a f the passive sensors while the squares give th sensing scattering modes.