Academic Visitors from the City University of Hong Kong hosted by SYMETA

On Friday 2nd June 2017, SYMETA will be hosting a visit from Professor Kwai Man Luk and Professor Chi Hou Chan from City University of Hong Kong. The professors will be sharing their work with staff and students from across the campus and holding discussions with SYMETA researchers to explore areas of mutual research interest.

Professor Kwai Man Luk is currently Chair Professor of Electronic Engineering at the City University of Hong Kong. His recent research interests include design of wideband patch antennas, dielectric resonator antennas, microwave and antenna measurements, and millimeter wave technologies. He is the author of 3 books, 11 research book chapters, over 350 journal papers and 250 conference papers. He was awarded 5 US patents and over 10 PRC patents on the designs of various printed antennas. He is a Fellow of IEEE, IET, CIE, FEA and HKIE. He received the Japan Microwave Prize at the Asia Pacific Microwave Conference in 1994, the Applied Research Excellence Award of City University of Hong Kong in 2001, the Croucher Award of Hong Kong in 2003, the Best Student Paper Awards (with his students) at the Asia Pacific Microwave Conferences in 2005 and 2006, and the Best Paper Awards at the International Symposium on Antennas and Propagation in 2008 and at the IEEE 4th Asia Pacific Conference on Antennas and Propagation in 2015. He was awarded the State Technological Invention Award of China (2nd Honor) in January 2012. He was the chief guest editor of a special issue on “Antennas in Wireless Communications” for Proceedings of the IEEE, published in July 2012. He is a deputy editor-in-chief of PIERS journals and an associate editor of IET Microwaves, Antennas and Propagation.

He will be speaking on Wideband Magneto-electric dipole antennas for millimetre-wave and terahertz frequencies

Wideband reflector-backed dipole antennas are simple in configuration but their radiation patterns vary substantially over their operating frequency ranges. Microstrip patch antennas are low in profile but narrow in bandwidth. Although various methods are available to increase their bandwidths, the radiation patterns and gains of wideband patch antennas fluctuate undesirably over the operating frequencies. Ten years ago, a new class of wideband antennas designated as the magneto-electric dipoles was proposed. These antennas were designed based on the complementary antenna concept. The basic structure consists of a planar electric dipole and a shorted quarter-wave patch antenna, with an L-shaped probe feed. These novel antenna elements have many attractive features, including wide impedance bandwidth, low cross polarization, low back radiation, nearly identical radiations in the two principal planes, stable radiation pattern, and constant antenna gain over the operating frequency range. They can be designed with linear polarization, circular polarization or dual polarization.

Magneto-electric dipoles have been successfully developed for applications in lower microwave frequencies. The structures, however, cannot be simply scaled up for applications in higher microwave frequency bands which will be occupied by future 5G mobile systems. In this talk, the latest development of the magneto-electric dipoles and arrays operated at the millimeter-wave and terahertz bands will be presented, with emphasis on different feeding methods for different applications, including coplanar waveguide and substrate integrated waveguide feeds.

Professor Chi Hou Chan received the B.S. and M.S. degrees in electrical engineering from the Ohio State University, Columbus, OH, USA, in 1981 and 1982, respectively, and the Ph.D. degree in electrical engineering from the University of Illinois, Urbana, IL, USA, in 1987. From 1987 to 1989, Dr. Chan was a Visiting Assistant Professor in the Department of Electrical and Computer Engineering at the University of Illinois. He joined the Department of Electrical Engineering at the University of Washington, Seattle, USA as an Assistant Professor in 1989 and was promoted to Associate Professor with tenure in 1993. In 1996, he joined the Department of Electronic Engineering, City University of Hong Kong as a Professor, and was promoted to Chair Professor of Electronic Engineering in 1998. From 1998 to 2009, he was first Associate Dean and then Dean of College of Science and Engineering. He also served as Acting Provost of the university from July 2009 to September 2010. He is currently the Director of State Key Laboratory of Millimeter Waves, Partner Laboratory in the City University of Hong Kong. His current research interests include computational electromagnetics, millimeter-wave circuits and antennas, and terahertz science and technology. Dr. Chan received the U.S. National Science Foundation Presidential Young Investigator Award in 1991 and the Joint Research Fund for Hong Kong and Macao Young Scholars, National Science Fund for Distinguished Young Scholars, China, in 2004. He received outstanding teacher awards from the Department of Electronic Engineering, CityU in 1998, 1999, 2000, and 2008. He is the General Co-Chair of ISAP 2010, iWAT2011, iWEN 2013, ICCEM 2015, ICCEM 2016 and GSMM2017.

He will be speaking on THz Wave Manipulation using metasurfaces.

Mankind has a long history of manipulating electromagnetic waves. The Olympic torch has been lit by focusing light rays from the sun using a parabolic mirror at the Temple of Hera in Olympia, Greece since the ancient times. Many distinguished scientists including Sir W. L. Bragg attempted to explain optical illusions in ancient Chinese bronze mirrors, where the pattern embossed on the mirror’s back can be projected onto a wall when the seemingly featureless reflecting surface is illuminated by light. It is found that by incorporating artificial features, imperceptible to the naked eye, on the mirror surface would allow us to alter the conventional understanding of wave phenomena.

In the talk, he will present recent works on metasurfaces for wave manipulations at THz frequency band in terms of angles of reflection and refraction, beam splitting, beam scanning and polarization conversion. Each metasurface consists of one or more substrate layers printed with arrays of metallic patches. Each unit cell or pixel of the metasurface has to be carefully designed with specific scattering amplitude and phase. Dispersion effect of the pixel needs to be tightly controlled for wideband operation. In contrast, it should be exploited for frequency beam-scanning applications. The metasurfaces are fabricated using either printed-circuit-board technology or micromachining, depending on if the operating frequency is below or above 0.3 THz. Due to the limitation of available power and dynamic range of the testing equipment, taking THz measurement is not a trivial task. In this talk, we will also share some of the difficulties encountered and present our purpose-built measurement platforms for validating our designs.

If you are interested in attending the seminars then please contact Kate Clift.

#Research #outreach

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