Speakers:
Professor Donald R. Wilton, University of Houston
Professor David R. Jackson, University of Houston
Professor Ji Chen, University of Houston
Title:
Half-Day Workshop on Applied Electromagnetics
Date:
Monday, July 19, 2010
Time:
9:00 am - 12:00 noon
Location:
DC 1302
Abstract:
Evaluation of Green's Functions For Layered Media - Donald R. Wilton
Layered media appear in many applications ranging from geophysical
problems to integrated circuits and metamaterial modeling. Frequency
domain Green's functions for layered media problems are needed
for integral equation modeling, and may be derived by reducing them
to a superposition of equivalent transmission line problems whose
characteristic impedances are the wave impedances of the TE and
TM plane waves supported by the structure, and whose sources are
equivalent series voltage and shunt current sources on the lines.
For single-source Green's functions, the superposition is over all the
transverse wave vectors, resulting in Sommerfeld-like integrals. In the
periodic case, the superposition is sum over discrete, periodic samples
of the transverse wave vectors. The mixed potential Green's function
representation of Michalski further transforms the field representation
into a form convenient for numerical work since only weak (integrable)
singularities arise. The numerical evaluation of these representations
may be accelerated by removing direct and quasi-static contributions from
the spectral representation. For non-periodic Green's functions,
the "tail" of the Sommerfeld spectral integral may be further
accelerated via the method of averages. For periodic Green's
functions, the spectral sums may be accelerated via the Ewald method.
Further speedup may be achieved by interpolating tables of regularized
(smoothed) forms of the Green's function.
Planar Leaky-Wave Antennas - David R. Jackson
Leaky-wave antennas use a traveling wave to radiate continuously along a
radiating aperture in order to produce a focused beam of radiation. Planar
leaky-wave antennas are particularly attractive since they use simple
dielectric layers and/or metallic screens over a grounded substrate
layer. A simple source such as a dipole or slot inside the substrate or
on the ground plane excites the leaky waves, which propagate radially
outward on the structure, producing a beam. The beam may be either a
pencil beam at broadside, or a conical beam, depending on the desired scan
angle. In this talk several examples of planar leaky-wave antennas will be
given, including those composed of high-permittivity dielectric layers,
planar metallic patches or slots, and metallic strips. The performance
characteristics will be examined in some detail and it will be shown how
the basic properties of all such antennas may be examined in a general
manner by studying a canonical structure that consists of a "partially
reflecting surface" over a grounded dielectric layer. The case of a
metamaterial substrate will also be examined to explore if advantages
can be realized with such materials. Finally, the interesting optical
phenomenon of directive beaming will be explored, and it will be shown
that this is also due to a leaky wave propagating on the planar structure.
Time Domain Modeling for Nano-Scale Periodic Structures - Ji Chen
Periodic structures exhibit many interesting electromagnetic
characteristics. However, efficient electromagnetic modeling of these
structures in time domain are often difficult, in particular if the
electromagnetic sources have finite extend. In this talk, we shall review
some new development in this area, such as spectral FDTD for periodic
structure modeling, the array-scanning-method (ASM) FDTD modeling of the
interactions between finite-sized electromagnetic and periodic structures,
and the effective electrical parameters extraction for composite material
using these techniques for EMC applications.
Biography:
Donald R. Wilton was born in Lawton, OK, on October 25, 1942. He
received the B.S., M.S., and Ph.D. degrees from the University of
Illinois, Urbana-Champaign, in 1964, 1966, and 1970, respectively. From
1965 to 1968 he was with Hughes Aircraft Co., Fullerton, CA, engaged in
the analysis and design of phased array antennas. From 1970-1983 he was
with the Department of Electrical Engineering, University of Mississippi,
and since 1983 he has been Professor of Electrical Engineering at the
University of Houston. From 1978-1979 he was a Visiting Professor at
Syracuse University. During 2004-2005 he was a visiting scholar at
the Polytechnic of Turin, Italy, the Sandia National Laboratories,
and the University of Washington. His primary research interest is in
computational electromagnetics, and he has published, lectured, and
consulted extensively in this area.
Dr. Wilton is a Life Fellow of the IEEE and received the IEEE Third
Millenium Medal. He has served the IEEE Antennas and Propagation Society
as an Associate Editor of the Transactions on Antennas and Propagation,
as a Distinguished National Lecturer, and as a member of AdCom. Dr. Wilton
is also a member of Commission B of URSI, in which he has held various
offices including Chair of U. S. Commission B.
David R. Jackson was born in St. Louis, MO on March 28, 1957. He
obtained the B.S.E.E. and M.S.E.E. degrees from the University of
Missouri, Columbia, in 1979 and 1981, respectively, and the Ph.D. degree
in electrical engineering from the University of California, Los Angeles,
in 1985. From 1985 - 1991 he was an Assistant Professor in the Department
of Electrical and Computer Engineering at the University of Houston,
Houston, TX. From 1991 to 1998 he was an Associate Professor in the same
department, and since 1998 he has been a Professor in this department. His
present research interests include microstrip antennas and circuits,
leaky-wave antennas, leakage and radiation effects in microwave integrated
circuits, periodic structures, and EMC. He is presently serving as the
Chair of the Transnational Committee of the IEEE AP-S Society. He is also
on the Editorial Board of the IEEE Transactions on Microwave Theory and
Techniques. Previously, he has been the Chapter Activities Coordinator
for the IEEE AP-S Society, a Distinguished Lecturer for the AP-S Society,
an Associate Editor for the IEEE Transactions on Antennas and Propagation,
and a member of the AdCom for the AP-S Society. He has also previously
served as the Chair for URSI, U.S. Commission B. He has also served as
an Associate Editor for the Journal Radio Science and the International
Journal of RF and Microwave Computer-Aided Engineering.
Ji Chen received the Bachelor's degree from Huazhong University
of Science and Technology, China, the Master's degree from McMaster
University, Canada, in 1994, and the Ph.D. degree from the University of
Illinois at Urbana-Champaign in 1998, all in electrical engineering. He
is currently an Associate Professor with the Department of Electrical and
Computer Engineering, University of Houston, Houston, TX. Prior to joining
the University of Houston, from 1998 to 2001, he was a Staff Engineer
with Motorola Personal Communication Research Laboratories, Chicago,
IL. Dr. Chen has received outstanding teaching award and outstanding
junior faculty research award from College of Engineering at University of
Houston. His research group also received the best student paper award at
IEEE EMC Symposium 2005 and the best paper award from IEEE APMC conference
in 2008. He is currently as a Distinguished Lecturer for IEEE EMC Society.
Invited by:
Prof.
S. Safavi-Naeini and Research in Motion.
Presented by the IEEE MTT/AP Chapter.
