Prof. Chung-Tse Michael Wu
Rutgers, The State University of New Jersey
ABSTRACT: Metamaterials (MTMs) are artificial electromagnetic materials with novel effective medium properties that may not be available in nature. The concept of metamaterial structures has led to the design of many novel circuits exhibiting component enhancements. One type of metamaterial-based antenna structure is so-called composite right/left-handed transmission line (CRLH-TL) leaky-wave antennas (LWAs). This kind of antenna structure has been shown to offer significant advantages over conventional LWAs. For example, a balanced CRLH-TL LWA is able to achieve continuous backfire-to-endfire frequency-dependent beam scanning with a true broadside beam, good impedance matching over an entire operating band with a simple feeding structure. Utilizing the frequency-space mapping characteristics of CRLH LWAs, the locations of unknown targets can be determined by simply reading the spectral components of the reflected wave. This results in a real time detection scheme since the data acquiring speed is mostly depending on the frequency sweeping speed of signal source, which is typically on the order of milliseconds. Such speed can be further increased if pulse signals are used. Furthermore, the field-of-view of the sensor can be enlarged due to the wide scanning angle provided by CRLH LWAs. Leveraging this unique feature of MTM antennas, various applications including fast 2-D beamforming, real-time remote sensing with large field-of-view that can be used in automotive radars, and microwave tomography with low complexity and cost can be realized. The next part of this talk will be on negative group delay (NGD) circuits, another kind of artificial materials engineered to exhibit superluminal group velocities. Conventionally, in microwave regime, NGD circuits are realized using bandstop structures with lumped elements, such as parallel RLC resonators; however, they usually have a narrower NGD bandwidth and also lack a systematic design methodology. Toward this end, NGD circuits based on a microwave transversal filter approach are proposed and shown to have a wide bandwidth of NGD with a comprehensive design method. The fully distributed nature of these NGD circuits make them feasible to further operate at high frequency range. Moreover, it will also be demonstrated that this new kind of transversal-filter based NGD circuit can realize non-Foster elements, i.e. negative inductors and/or capacitors, with potentially unconditional stability and reconfigurability, which is expected to have a great impact on realizing stable non-Foster elements in microwave and millimeter wave regimes. It is envisioned by using these artificially engineered metamaterial based antennas and components, next-generation microwave imaging and communication systems, as well as microwave components with enhanced functionalities and performance will be enabled.
BIOGRAPHY: Dr. Chung-Tse Michael Wu is an assistant professor in the Department of Electrical and Computer Engineering at Rutgers, The State University of New Jersey. His research interests include applied electromagnetics, antennas, passive/active microwave and millimeter-wave components, RF systems and metamaterials. He received his B.S. degree from National Taiwan University (NTU) in 2006. He then received his M.S. and Ph.D. degree in the Department of Electrical Engineering, University of California at Los Angeles (UCLA) in 2009 and 2014, respectively. From September 2008 to June 2014, he worked as a graduate student researcher at the Microwave Electronics Laboratory in UCLA. In 2009, He was a summer intern in Bell Labs, Alcatel-Lucent, Murray Hills, NJ. In 2012, he was a special-joint researcher at Japan Aerospace Exploration Agency (JAXA) in Kanagawa, Japan. From 2014 to 2017, he was an assistant professor in the ECE department, Wayne State University (WSU) in Detroit, Michigan. Dr. Wu was also a visiting assistant professor at National Chung Hsing University, Taichung, Taiwan, in summer 2017. In 2016, Dr. Wu received National Science Foundation (NSF) Faculty Early Career Development (CAREER) Award, as well as WSU College of Engineering Faculty Research Excellence Award. He was also a recipient of 2011 IEEE Asia Pacific Microwave Conference (APMC) Student Prize and a recipient of 2013 IEEE APMC Best Student Paper Award. In addition, he received the second place award in 2014 IEEE International Microwave Symposium (IMS) student design competition. He is a Member of IEEE, IEEE-MTTs, IEEE-APS and IEEE-ComSoc.