Millimeter-Wave Radar-in-Display for Target Characterization and Micro-Doppler Sensing

This article presents a novel millimeter-wave (mmWave) frequency-modulated continuous-wave (FMCW) radar-in-display (RiD) concept for target characterization and micro-Doppler sensing. The radar system comprises one transmitter and three receivers, integrated along the nonoptical dead space (DS) (<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$300~\mu $ </tex-math></inline-formula> m) at the edges of a display panel. For 2-D scanning, one receiving (RX) antenna is positioned on the vertical edge, while the other two, along with the transmitter, are placed on the horizontal edge. A notched monopole antenna is mounted on the vertical edge, and capacitively coupled slot dipole antennas are used for the horizontal edge. The slot dipoles are designed to align polarization with the monopole antenna mounted at the perpendicular DS based on feed asymmetry. The antennas are integrated into the display panel and connected to a radio frequency integrated circuit to realize the RiD prototype. The prototype is validated through various hand gesture experiments, with spectrograms showing range, micro-Doppler shift, azimuth, and elevation angles after postprocessing. A novel calibration process is also presented in the postprocessing to correct phase errors caused by the unconventional array configuration, near-field (NF) effects, and radar components. The results demonstrate that the RiD system captures distinct gesture signatures with resolutions of 3 cm and 0.19 m/s.