1. Key Laboratory of Radar Imaging and Microwave Photonics, College of Electronic and Information Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing 211106, China;
2. Nanjing Research Institute of Electronics Technology, Nanjing 210039, China;
3. State Key Laboratory of Satellite Navigation System and Equipment Technology, Shijiazhuang 050081, China