An image quality improvement method under sparse array and small bandwidth in MIMO IR-UWB imaging system

In this paper, we proposed a new algorithm to improve the image quality degradation due to sparse array topology and small fractional bandwidth of commercial radar chip in two-dimensional (2-D) multiple-input-multiple-output (MIMO) impulse radio ultra-wideband (IR-UWB) array imaging system. The new algorithm, which adds a clustering concept and signal windowing method to the existing delay-and-sum (DAS) algorithm, enables short range imaging in a practical environment with fewer antenna placement and fractional bandwidth of less than 100%. Experiments were performed on human mannequin targets using a sparse cross array topology with an antenna spacing of 2.0λ and a commercial IR UWB radar chip with a fractional bandwidth of 34%. The test results show that several spurious images and image quality degradation, including grating lobes, occurring in the conventional DAS imaging algorithm are completely improved in the new algorithm. Therefore, the results of this paper show that the short-range IR-UWB radar imaging system may be used in real commercial applications in the future.