Distance Measurement Using mmWave Radar: Micron Accuracy at Medium Range

This work provides a proof-of-concept for a linear-position sensor using an ultrawideband (UWB) frequency-modulated continuous wave (FMCW) radar system operating at 126–182 GHz. It is the first work to show environmental compensated and calibration-free distance measurements with micron accuracy at medium range using millimeter-wave (mmWave) radar technology. We addressed hardware imperfections, parameter estimation, and the free-space path, i.e., refractive index and near-field effects. The proposed signal processing chain is robust to interference and of low computational cost. Experiments reveal a systematic error of $\pm 1~\mu \text{m}$ over 4.8 m (0.8–5.6 m), and a random error at a minimum of 30 nm, providing very high sensitivity.