1. EMC Research and Measurement Center of Navy, 200235 Shanghai, China
2. College of Electronics Science and Engineering, National University of Defense Technology, 410073 Changsha, China
3. PLA Naval Command College, 211800 Nanjing, China
4. Dipartimento di Ingegneria Elettrica ed Elettronica, University of Cagliari, 09123 Cagliari, Italy