Wall compensation in imaging of hidden targets behind multiple walls

In through-wall-radar imaging (TWRI), this paper presents a fast wall compensation algorithm to deal with the problem of image defocusing and displacement of the target behind multiple parallel and equivalent walls in the case of the known wall parameters including thickness and relative permittivity. Based on the Snell law, we combine these walls into a virtual wall by translating the second wall to the edge of the first wall but keep the focusing delay same. Therefore, instead of searching for multiple refraction points on the surfaces of the multiple actual walls, we just need to find a refraction point on the surface of the virtual wall to calculate the focusing delay rapidly in back-projection imaging. Additionally, the time minimization method is utilized to seek the refraction point. The simulation results demonstrate the image of target behind two walls is focusing and located at the accurate target position using the presented fast compensation algorithm.