Through wall radar imaging using multiple antennas and beam forming

Abstract

Through‐the‐Wall radar imaging (TWRI) is emerging as a viable technology for providing high quality imagery of enclosed structures. TWRI makes use of electromagnetic waves below the S‐band to penetrate through building wall materials. The indoor scene can be illuminated from each antenna, and be reconstructed using the data from the receive antennas. Due to the “see”‐through ability, TWRI has attracted much attention in the last decade with a variety of important civilian and military applications. For instance, this technology is employed for surveillance and detection of humans and interior objects in urban environments, and for search and rescue operations in military situations. Strong front wall returns tend to obscure indoor targets and render through-the-wall target detection difficult and challenging. Subspace projection method is used for wall clutter mitigation. At first, near field and through the wall propagation effects on electromagnetic waves are addressed then a MIMO frequency signal model is given and the advantages of a MIMO scheme for the complex task of TTW detection is discussed. Then image formation with beamforming processing is derived. Finally, the proposed imaging method is implemented considering through cinder blocks walls propagation. The obtained images for a scenario with two targets are presented. Difficulties in TTW detection and imaging with MIMO radar architecture have been overcome. Efficiency is increased in terms of clutter reduction, noise reduction, target parameter enhancement and improved target tracking. Resolution of the system is increased with reduction in clutter and improvement in signal to noise ratio.