Ultra wideband radar systems are of great interest in terms of applications to security surveillance systems in preventing crime where conventional camera-based systems cannot be used. Such systems require an antenna array with high-frequency switches to sequentially measure signals at different antenna positions. Targets are, however, not always cooperative in that during antenna scanning they might not be still. We propose a method for estimating target motion using the revised range point migration method and an image sharpness metric. The performance of the method is assessed by taking measurements of three moving targets: a corner reflector, a handgun and a knife in part to establish its applicability in detecting weapons.