Grating Lobe Suppression in Sparse Array-Based Ultrawideband Through-Wall Imaging Radar

The use of a sparse through-wall radar array can significantly reduce the complexity and the costs of a radar system. However, due to insufficient spatial sampling, a sparse array often suffers from strong grating lobes that seriously degrade image quality. To suppress grating lobes, we first divided the whole array aperture into two subapertures to examine the method of aperture difference. However, this method suppressed only the grating lobes in the edge region rather than in the middle region. Thus, cross-correlation of the two subapertures was proposed, which would mainly reduce grating lobes in the middle region. In this letter, a novel method of cross-correlation weighting of aperture difference is proposed, which shows great feasibility in suppressing grating lobes in both regions. Results from experiments are in agreement with the theory and simulation outcomes and show a dramatic improvement in image quality.