1. Laboratory for General and Theoretical Electrical Engineering (ATE), Faculty of Engineering, University of Duisburg-Essen, and CENIDE–Center for Nanointegration Duisburg-Essen, Duisburg, Germany
2. Nanjing Research Institute of Electronics Technology, Nanjing, China
3. Department of Microwave Engineering, School of Electronic and Information Engineering, Harbin Institute of Technology, Harbin, China