Squinted array beamforming for wall back plate detection

We consider the problem of detection of wall back plates, which intentionally or unintentionally block electromagnetic wave penetrations and prevent the waves from reaching the indoor scene. This renders the result of through-the-wall radar imaging incorrect and misleading. The proposed approach employs squint beamforming to avoid the strong direct returns from the front side of the exterior wall and allow the diffraction for the plate placed against or near to the back side of the wall to be detected. We aid squint beamforming with a wall removal technique based on eigenstructure of the data matrix. This technique is applied prior to imaging and mitigates sidelobe wall scattering residuals, which may still obscure the relative weak plate radar return.