An Efficient ISAR Imaging Method of the Rotors of Small UAVs via Simplified CIRT

The radar imaging of the rotors of unmanned aerial vehicles (UAVs) has great help to the detection and recognition of the UAVs. Most existing inverse synthetic aperture radar (ISAR) imaging methods can only obtain the image of the rigid body, whereas the study on the imaging of rotors is still facing challenges such as low resolution and heavy computational burden. In this study, a simplified complex inverse radon transform (CIRT) based method is proposed to reconstruct the images of the rotors with high efficiency. According to the characteristics of the rotor echoes, a parameterized phase matching based strategy is designed to estimate the initial phase angle of the rotor in the imaging interval. Then the sectors of interest in the imaging plane can be distinguished, so that the CIRT can be accelerated via sparse matrix calculations. Compared with traditional methods, the proposed method maintains the high imaging resolution and reduces the redundant calculations by taking full advantages of the rotor geometric characteristics. Experiments on simulated and measured data have verified that our proposed method can achieve high quality images of the rotors, and it takes only 40% of the memory and running time of traditional CIRT method.