Near-Field Millimeter-Wave Imaging via Multi-Plane MIMO Arrays.

Multiple-input multiple-output (MIMO) array-based millimeter-wave (MMW) imaging has broad application prospects in concealed weapons detection due to its capability of high resolution at a reasonable cost. This paper presents a novel multi-plane MIMO array topology for near-field MMW imaging. The multi-plane MIMO arrays can offer wider angular observations of the target under test than the traditional planar MIMO arrays. Although the cylindrical MIMO array can achieve similar focusing performance as the multi-plane one, the multi-plane MIMO arrays are much easier to fabricate since each subarray has the same structure as a planar one. In addition, to speed up the image reconstruction process, we propose a corresponding three-dimensional (3-D) imaging algorithm with hybrid processing in the time-domain and wavenumber-domain. The proposed algorithm is even more efficient than the wavenumber-domain algorithm for the cylindrical MIMO array that has the same scale as the proposed multi-plane array scheme, which clearly shows that the hybrid time-wavenumber domain processing can avoid the enormous computation burdens of higher dimensional processing of the wavenumber-domain MIMO imaging algorithms. Numerical simulations and experimental results are provided to demonstrate the superiority of the proposed multi-plane MIMO array imaging technique in comparison with the most commonly used arrays and algorithms.