Time: 11:00am - 12:00pm Venue: Graduate Centre 205, QMUL
Title: Metasurface for Efficient Control of Electromagnetic Wave Scattering
Speaker: Prof. Yijun Feng, School of Electronic Science and Engineering, Nanjing University, China.
Abstract:
Controlling the electromagnetic (EM) wave scattering is an important issue in many practical applications such as in the EM interference, EM compatibility, as well as in EM stealth technique. Recently, the newly developed metasurface concept which represents for planar metamaterial composed of two-dimensionally arranged sub-wavelength meta-atoms has demonstrated its substantial ability to generate arbitrary wavefront by imparting spatially varying phase-discontinuities to the incident EM wave. As a new opportunity of EM wave scattering control technique, I we will present our recent research examples of applying metasurfaces to EM wave absorption, EM scattering control, and radar cross section (RCS) reduction. I will discuss on designing different metasurfaces for microwave energy absorption, and pay particular attentions on how to expand the working bandwidth of metasurface absorbers. As an interesting example of how the metasurface can improve the conventional method of EM scattering control, I will introduce metasurface to the conventional Salisbury screen to establish the so-called ‘Metasurface Salisbury Screen (MSS)’. Through a two-step optimization procedure we have successfully achieved a microwave absorption with four octave bandwidth from a prototype MSS design. The arbitrary reflection phase control ability of metasurfaces offers a new solution to achieve RCS reduction. Here I will also show by randomly distributing reflective meta-atoms with different reflection phases along the surface, the metasurface can generate a diffuse-like EM scattering, which could largely reduce the backward scattering from metallic object coated with the metasurface. I also extend the diffusive metasurface designs to flexible and optically transparent cases bringing more application possibilities.
Biography: Yijun Feng received the M.Sc. and Ph.D. degrees from the Department of Electronic Science and Engineering, Nanjing University, in 1989 and 1992, respectively. Since 1992, he has been a faculty member and is currently a full professor and the director of Microwave Technology Lab in the School of Electronic Science and Engineering, Nanjing University. From September 1995 to July 1996, he was a visiting scientist with the Physics Department, Technical University of Denmark. From August 2001 to August 2002, he was a visiting researcher with the University of California at Berkeley. Prof. Feng’s research interests include the electromagnetic metamaterial and application to microwave and photonic devices, electromagnetic wave theory, and novel microwave functional materials. He has conducted more than twenty scientific research projects including National 973, 863 Projects and the National Natural Science Foundation projects in China. He has received the 2010 Science and Technology Award (First grade) of Jiangsu Province, China, and the 1995 Scientific and Technological Progress Award by Minister of Education, China. He has authored or co-authored over 150 journal papers and over 120 referred international conference papers.