Near-field Three-dimensional Imaging of Large MIMO Arrays Based on Spatial Phase Compensation

The growing interest in active millimeter-wave and microwave imaging systems is driven by their applications in security, healthcare, and industrial fields. However, imaging systems using single antenna arrays suffer from low efficiency, and Multi-Input Multi-Output (MIMO) radar imaging systems often lack far-field conditions at short distances. In this paper, we propose a novel MIMO near-field imaging algorithm specifically designed for large millimeter-wave radar systems. By employing a linear approximation to compensate for the spatial quadratic phase at a single reference point, the algorithm enables the application of FFT-based imaging techniques within a defined range. The paper details the imaging range applicable to a single reference point, as well as the calculation method and imaging steps for multiple reference points in global imaging. Experimental results demonstrate that the proposed algorithm effectively focuses target energy, enabling real-time 3D near-field imaging for real aperture arrays.