Reconfigurable Frequency–Spatial Equivalent Array Based on FMCW Radar for Accurate Close-Spaced Multitargets Motion Sensing

Frequency-modulated continuous-wave (FMCW) radar has been widely utilized for target detection and motion sensing. However, conventional techniques are constrained by radar bandwidth, spectral leakage, and noise, making the separation and accurate detection of multiple targets within range resolution a significant challenge. To address these limitations, a reconfigurable frequency-spatial equivalent array (RFSEA) technique is proposed. A frequency-domain virtual array is constructed by exploiting the characteristics of the spatial array, effectively improving the signal-to-noise ratio (SNR), enhancing the performance of the subspace algorithm, and significantly substantially increasing range resolution to achieve more accurate close-spaced multitargets separation. In addition, the introduction of frequency-domain adaptive digital beamforming (FDADBF) technology minimizes mutual interference caused by spectral leakage, facilitating highly accurate motion measurement. Simulation and experimental results demonstrate that the proposed technique improves range resolution by 42.8%, achieves motion measurement within range resolution with average root-mean-square errors (RMSEs) below 10%, and delivers a threefold improvement in accuracy compared to conventional methods. These findings underscore the potential of RFSEA in advancing high-resolution and precise motion sensing applications.