Fast and Shadow Region 3-Dimensional Imaging Algorithm With Range Derivative of Doubly Scattered Signals for UWB Radars

Ultra-wideband (UWB) radar with its high range resolution and applicability to optically harsh environments, offer great promise for near field sensing systems. It is particularly suitable for robotic or security sensors that must identify a target in low visibility. Some recently developed radar imaging algorithms proactively employ multiple scattered components, which can enhance an imaging range compared to synthesizing a single scattered component. We have already proposed the synthetic aperture radar (SAR) method considering a double scattered, which successfully expanded a reconstructible range of radar imagery with no a priori knowledge of target or surroundings. However, it requires a multiple integration of the received signals, requiring the fifth times integration in the 3-D case. Thus, this method requires an intensive computation and its spatial resolution is insufficient for clear boundary extraction such as edges or specular surfaces. As a substantial solution, this paper proposes a novel shadow region imaging algorithm based on a range derivative of double scattered signals. This new method accomplishes high-speed imaging, including a shadow region without any integration process, and enhances the accuracy with respect to clear boundary extraction. Results from numerical simulations verify that the proposed method remarkably decreases the computation amount compared to that for the conventional method, especially for the 3-D problem, enhancing the visible range of radar imagery.