MIMO Array-Radiation-Pattern Optimization for Effective-Field-of-View Enhancement in MMW Short-Range Imaging

Insufficient effective-field-of-view caused by narrow-beam antennas in millimeter-wave (MMW) multi-input multi-output (MIMO) short-range imaging greatly reduces the synthesis efficiency of the MIMO array, resulting in a severe degradation of imaging performance. Therefore, in this article, an array-radiation-pattern optimization is proposed to address this problem. The proposed method is simple yet effective to implement by adjusting the beam pointing of each antenna. For simplifying the computational complexity, the solution of 2-D angles of beam pointing is converted into an optimization of 1-D amplitude weighting and their unique remapping then is guaranteed based on the measured radiation pattern of the antenna and the layout of MIMO arrays. In such a way, the beam pointing of each antenna in the MIMO array is inclined on purpose rather than perpendicular to the array plane as usual. Simulations and experiments are performed to demonstrate the availability of the proposed method, and reveal that it can effectively assist the MMW MIMO array in achieving high-resolution imaging in short-range applications.