Extended imaging method using range-points-based ellipse extrapolation with double-scattered waves for UWB radar

Ultra-wide band pulse radar has a higher range resolution. It is promising as a near field sensor for rescue robots or security systems, where an accurate 3-dimensional measurement impervious to optical environments is indispensable. However, in typical indoor sensing situations, aperture size is severely limited by obstacles such as collapsed furniture. The available radar image is then too narrow to identify a target, whether a human body or other objects. To avoid this difficulty, we previously proposed the image expansion method based on the ellipse extrapolation, where the fitting space is converted from real space to data space defined by range points to enhance the extrapolation accuracy. Although this method achieves an accurate image expansion in some cases, by exploiting the feature of the efficient imaging method as range points migration, there are still many cases where it cannot maintain sufficient extrapolation accuracy because it only employs the single scattered component for imaging. To address the above issue, this paper extends the above image expansion method by exploiting double-scattered signals between target and wall of indoor environments. The results from numerical simulation, including noise, exemplify that the proposed method significantly expands the extrapolated region for multiple elliptical objects.