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Near-field ultra-wideband imaging with two-dimensional sparse MIMO array

In this paper, we investigate the feasibility of utilizing the concept of effective aperture for designing sparse multiple-input multiple-output (MIMO) array oriented for ultrawideband (UWB) near-field imaging. The array design approach based on the effective aperture concept was previously applied under narrowband far-field conditions. Numerical and experimental studies are performed to show that such method can be still feasible in the near-field of the UWB array aperture. Two-dimensional MIMO array is designed based on the design method with extension using the principle of separable aperture functions. The real 2-D aperture array is compared with its effective aperture measured with synthetic aperture radar (SAR) technique. The similarity of their beam pattern and imaging capabilities confirm the feasibility of the effective aperture approach, and demonstrate the potential of UWB near-field imaging system with 2-D sparse multi-static array configuration.