1. National Key Laboratory on Vacuum Electronics, School of Electronic Science and Engineering, University of Electronic Science and Technology of China (UESTC), Chengdu, China
2. School of Electrical Engineering and Automation, Jiangxi University of Science and Technology, Ganzhou, China
3. Nanjing Sanle Microwave Technology Development Company Ltd., Nanjing, China
4. National Key Laboratory on Vacuum Electronics, Beijing Vacuum Electronics Research Institute, Beijing, China