Accurate shadow region imaging algorithm using ellipse extrapolation based on distorted hyperbola fitting for UWB radars

Ultra-wideband (UWB) pulse radars have a definitive advantage in high-range resolution imaging and are suitable for near-field measurements. Although we have already proposed an accurate imaging algorithm called Range Points Migration (RPM), the reconstructible area of RPM is too small to identify an object shape when the object is far from the observation site in the case of limited aperture size. To resolve the problem, this paper proposes a novel image expansion method based on ellipse extrapolation, which is converted to distorted hyperbola fitting in the data space to enhance extrapolation accuracy. Numerical simulations show that the proposed method accurately extrapolates the target boundary, even if an extremely small region of the target boundary is obtained by the RPM.