Dr. Nader Engheta - Univ. of Pennsylvania
Thu, 29 April 2004, 8:00 AM - 12:00 PM
The concept of metamaterials has been the subject of research interest for many investigators worldwide. New concepts in synthesis and novel fabrication techniques may allow construction of new classes of composite materials with interesting electromagnetic properties. These metamaterials, which can in principle be synthesized by embedding various constituents/inclusions with novel geometrical shapes and forms in some host media, possess exciting features and response functions, not easily available in nature but physically realizable, with new potential applications in the design of devices and components. The electromagnetic properties of certain class of metamaterials in which both permittivity and permeability attain negative real parts in a given band of frequencies have attracted a great deal of interest in recent years. Various names, such as ?double-negative (DNG)? media, ?left-handed (LH) materials, ?backward-wave (BW) media?, ?negative index materials (NIM)?, have been coined for this type of metamaterials. These particulate composite media possess unconventional features such as negative refraction and backward wave propagation, in which the direction of the Poynting vector of a plane wave is antiparallel with the direction of its phase velocity. These can lead to some exciting wave characteristics with potential applications in various systems and subsystems involved in radiation, guidance and scattering of electromagnetic waves. In addition, the ?single-negative (SNG)? media, i.e., the materials in which only one of the material parameters of permittivity and permeability, but not both, can be negative, also exhibit certain interesting properties when they are paired in a conjugate manner. Another class of metamaterial structures in which the period arrangement of elements can provide interesting features is the electromagnetic bandgap (EBG) surfaces with high surface impedance. In such surfaces, by properly selecting the geometry, composition, arrangement and alignment of planar elements one can achieve high impedance surfaces, which can effectively behave as ?artificial magnetic conductors (AMC)? These can lead to useful applications in various problems involving low-profile, conformal antennas, miniaturized cavities, and thin absorbing low-observable surfaces.
In this tutorial, I will present a comprehensive overview of some of the selected topics in these areas. I will first give a brief background and history of this field, and will review some of the salient features of the metamaterials. I will then discuss in details some of the topics on metamaterials, including scattering and radar cross section properties of planar, cylindrical and spherical structures containing pairs of DNG-DPS and ENG-MNG metamaterial layers, waveguiding features of metamaterials, exciting properties of imaging systems containing layers of metamaterials, EBG surfaces acting as high-impedance surfaces and the role of space-filling and fractal geometries in forming such exotic ground planes for antenna applications, and several other related problems in the field of metamaterials with various potential applications in radar and antenna systems.
Dr. Nader Engheta - Univ. of Pennsylvania
Nader Engheta is a Professor in the Department of Electrical and Systems Engineering at the University of Pennsylvania. He received the BS degree in electrical engineering from the University of Tehran in 1978, the MS degree in electrical engineering and the Ph.D. degree in electrical engineering both from the California Institute of Technology (Caltech) in 1979 and 1982, respectively. From June 1982 to June 1983, he was a Postdoctoral Research Fellow at Caltech, and from June 1983 to June 1987, he was a Senior Research Scientist at Kaman Sciences Corporation, Dikewood Division, in Santa Monica, California. In July 1987, he joined the faculty of the University of Pennsylvania, where he is currently Professor of Electrical and Systems Engineering. He is also a member of the David Mahoney Institute of Neurological Sciences at the University of Pennsylvania, and a member of the Bioengineering Graduate Group at the University of Pennsylvania. He was the graduate group chair of electrical engineering from July 1993 to June 1997.
He is a Guggenheim Fellow, a recipient of the IEEE Third Millennium
Medal, a Fellow of IEEE and a Fellow of the Optical Society of America.
In addition, he has received various awards and distinctions for his
scholarly research contributions and teaching activities including the
UPS Foundation Distinguished Educator term Chair for July 1999-June
2000, the Fulbright Naples Chair award for Naples, Italy for 1998, a
1989 NSF Presidential Young Investigator (PYI) award, two times (1993,
2002) recipient of the S. Reid Warren, Jr. Award for distinguished
teaching from UPenn's School of Engineering and Applied Science, the
1994 Christian F. and Mary R. Lindback Foundation Award, and the W. M.
Keck Foundation's 1995 Engineering Teaching Excellence Award.
He is an Associate Editor of The IEEE Antennas and Wireless Propagation
Letters (2002-present), and was an Associate Editor for the IEEE
Transactions on Antenna and Propagation (1996-2001), and Radio Science
(1991-1996). He was on the Editorial Board of the Journal of
Electromagnetic Waves and Applications. He served as an IEEE Antennas
and Propagation Society Distinguished Lecturer for the period 1997-99.
He is a member of the American Physical Society (APS), the American
Association for the Advancement of Science (AAAS), Sigma Xi, Commissions
B and D of the U.S. National Committee (USNC) of the International Union
of Radio Science (URSI), and a member of the Electromagnetics Academy.
He was the Chair (1989-91) and Vice-Chair (1988-89) of the joint chapter
of the IEEE Antennas and Propagation / Microwave Theory and Techniques
in the Philadelphia Section. He is an elected member of the
Administrative Committee (AdCom) of the IEEE Society of Antennas and
Propagation since January 2003.
His research interests and activities are in the areas of fields and
waves phenomena, metamaterials and complex media,
bio-inspired/biomimetic polarization imaging and polarization vision,
wave interaction with unconventional complex structures and complex
surfaces, small antennas for wireless applications, bio-inspired
hyperspectral sensing, biologically-based visualization and physics of
sensing and display of polarization imagery, through-wall microwave
imaging, electromagnetics/electrophysics of brain cortical potentials
(e.g., EEG), millimeter-wave lensing systems, optics, fractional
operators and fractional paradigm in electrodynamics. He has guest
edited/co-edited several special issues, namely, the special issue of
Journal of Electromagnetic Waves and Applications on the topic of "Wave
Interaction with Chiral and Complex Media" in 1992, part special issue
of the Journal of the Franklin Institute on the topic of "Antennas and
Microwaves (from the 13th Annual Benjamin Franklin Symposium) in 1995,
special issue of the Wave Motion on the topic of "Electrodynamics in
Complex Environments" (with L. B. Felsen) in 2001, and special issue of
the IEEE Transactions on Antennas and Propagation on the topic of
"Metamaterials" (with R. W. Ziolkowski) in 2003.