Frequency-Domain Leakage and Stationary Clutter Cancellation Technique With a <i>K</i> -Band Short-Range End-to-End Sparse MIMO FMCW Radar System

Multiple-input-multiple-output (MIMO) frequency-modulated continuous-wave (FMCW) radar systems often encounter performance degradation in short-range applications. In particular, short-range leakages and stationary clutters can introduce interferences that obscure the detection of targets of interest, while traditional systems are limited by inadequate spatial resolution, which constrains their ability to acquire accurate point cloud data. To address these challenges, a <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">K</i>-band short-range end-to-end 2T4R sparse MIMO FMCW system was proposed and designed, achieving a threefold enhancement in point cloud acquisition capability. Based on this system, a 3-dB beamwidth of 8.97° and a measured angular resolution of 13.8° are achieved, corresponding to improvements of 29.8% and 32.8%, respectively, compared to the conventional uniform array, while a sidelobe level of −10 dB and a wide field of view of 100° are also demonstrated. Furthermore, a novel frequency-domain interferences (leakages and stationary clutters) cancellation technique (FDICT) has been introduced to eliminate interferences, significantly enhancing the system’s short-range detection performance. By exploiting the frequency-domain characteristics of the intermediate frequency (IF) signals, this technique effectively mitigates interferences, offering robust and versatile cancellation of multipath leakages and stationary clutters for both synchronous and asynchronous systems, thus enabling accurate point cloud acquisition. Simulations and experiments were conducted to validate the system. The results demonstrate that the radar achieved the expected performance, and the proposed technique effectively eliminates leakages and stationary clutters, leading to an average improvement of 15 dB in signal-to-interference ratio (SIR) across the entire spectral range. Compared to traditional systems, the proposed system demonstrates superior short-range sensing performance, making it particularly advantageous for short-range applications.