Magnitude Spectrum Reformatting in the f-k Domain for FMCW Radar Background Characterization and Mitigation

Recently, frequency-modulated continuous wave (FMCW) multiple-input multiple-output (MIMO) radar has been employed indoors for various applications, including target localization, automated people counting, and human vital signs detection. However, the signals collected by this radar technology are significantly affected by artifacts such as clutter and noise. The primary factors degrading radar performance include the direct coupling between transmit and receive antennas and the presence of stationary clutter within the experimental environment, collectively referred to as the background effect in radar imagery. This work aims to propose a space-time approach to mitigate the background effect. Specifically, the background is characterized in the frequency-wavenumber (f-k) domain using a mask function that attenuates magnitude spectrum components not corresponding to the background. The modified magnitude spectrum is then converted back to the space-time domain for background suppression. To evaluate the performance of the proposed method, realistic measurements were conducted in two scenarios involving human targets in continuous back-and-forth motion within a room. The results demonstrate effective background reduction and improved robustness to target signal degradation compared to other space-time approaches such as moving average, single-delay moving target indication (MTI), and high-pass filtering methods.