Serving Eastern Massachusetts
Antennas and Propagation Society [AP-03]
Antenna & Propagation; Microwave Theory & Techniques; and Aerospace & Electronic Systems Societies (This meeting has been postponed until September. Please watch the Reflector and eReflector for new date.)
6:00 PM, Thursday, 3 May
You Can Do That? Twenty Five Years of Fractal Antennas
Nathan Cohen, Fractal Antenna Systems, Inc.
Nathan Cohen is CEO of Fractal Antenna Systems, Inc. of Waltham, MA.
He is the founder of fractal antenna technology and holds over 2 dozen
patents on them. Previously he was an academic radio astronomer and
physicist who retired as a professor from Boston University in 2002. He
holds a Ph.D. from Cornell University and conducted his thesis work at
Haystack observatory on Very Long Baseline Interferometry (arrays) and
gravitational lenses. He has authored over 80 papers and 3 books.
This year marks the 25th year of the creation and recognition of fractal antennas as a new and worthwhile class of antenna design. Despite this longevity, published summaries remain poor in accuracy and detail, although fractal antenna advantages are unrealized with other design approaches. This talk presents a variety of ways in which fractal antenna technology (including fractal resonators and fractal metamaterials) has been used to produce: smaller, multiband antennas without components; wideband invariant antennas with huge bandwidths; sparse array that are frequency invariant and low in sidelobes; lower profile antennas with better performance on metal; extremely low RCS radar targets; fractal metasurface wideband radiators; wideband invisibility cloaks; rapid covergence design algorithms; and so on. I will also debunk claims about electrically small antennas; 'ecumenical' antenna performance; and so on, that have prevented more rapid progress in fractal antenna acceptance in the United States. A live demonstration will also be shown.
Meeting will be held at MIT Lincoln Laboratory A-Café, 244 Wood Street, Lexington, MA. For directions please see: http://www.ll.mit.edu/about/map.html
For more information, contact Antennas & Propagation chair, Raoul O. Ouedraogo, raoul.ouedraogo@ll.mit.edu
Microwave Theory & Techniques; Antennas & Propagation Societies and Aerospace & Electronic Systems Chapters
6:00 PM, Thursday, 19 April (refreshments served at 5:30 PM)
Low-Cost Ultrawideband (UWB) Phased Array Antennas - Importance, Challenges and Inroads
Prof. Marinos N. Vouvakis, University of Massachusetts Amherst
The two prevailing trends in modern communication and sensing system technologies are increased information throughput or functionality, and smaller sizes. From the physical-layer electronics perspective such as RF/microwave engineering, these trends translate into hardware with wider bandwidths and higher frequencies of operation. Yet, when it comes to the design of antenna arrays, that are necessary in every wireless communications, stand-off sensing or electronic countermeasure, these treads are in direct conflict with one another. Ultrawideband (UWB) phased arrays are significantly more challenging to design and build than their narrowband counterparts, whereas manufacturability constraints above X-band severely limit the effectiveness of bandwidth enhancement methods. These technical challenges are reflected in the skyrocketing price-tags of extremely high frequency (EHF) UWB arrays, and their limited use to select military or security applications.
Established UWB phased array technologies such as the Vivaldi array, or the fragmented aperture array or Monk’s current sheet array are either too complicated to build at EHFs, or require performance-limiting feeding methods to integrate with the rest of the phased array system, or cannot be easily installed or maintained due to lack of aperture modularity. This seminar will introduce a novel low-cost UWB phased array, the planar ultrawideband modular antenna (PUMA) that overcomes all these limitations. The PUMA array is extremely simple, making it easy to build with standard low-cost microwave fabrication techniques even above Ku-band, the key comes from its novel direct-feeding scheme that avoids altogether external baluns and elaborate feed-line shielding without performance degradation. Moreover, the carefully laid-out PUMA aperture allows for modular manufacturing with tiled assemble, leading to certain cost, installation, maintenance and robustness benefits.
After a brief introduction in ultrawideband/multifunctional systems and phased arrays, the talk will focus on the basic PUMA array topology, variations, principles of operation and modeling, and design and manufacturing approaches. The design, fabrication and measurements of an exemplary 7-21GHz PUMA design will be used to concretely demonstrate the technology. Several newer computational prototypes will be presented that operate at higher than 6:1 bandwidth. Important phased array aspects such as impedance matching (VSWR), coupling, radiation pattern, wide angle scanning, polarization purity, and fabrication cost will be used to scrutinize the quality of the designs. Time permitting, a short glimpse of the advanced in-house numerical modeling techniques, used to design the full finite PUMA array will be given.
Bio:
Dr. Marinos N. Vouvakis (S'99, M’05) is an Associate Professor of
Electrical and Computer Engineering (ECE) at the University of
Massachusetts Amherst, where he conducts research and teaching in the
areas of microwave and antenna engineering, and computational
electromagnetics. Dr. Vouvakis received the Diploma degree in ECE from
the Democritus University of Thrace (DUTH), Xanthi, Hellas, in 1999, he
holds a M.S. from Arizona State University (ASU), Tempe, AZ and a PhD
from The Ohio State University (OSU), Columbus OH, both in ECE. Since
2005 he is with the UMass ECE faculty as a member of the Center for
Advanced Sensor and Communication Antennas (CASCA) and the Antennas and
Propagation Laboratory (APLab). His main research interests are in
computational electromagnetics (CEM), where he is known for his
contributions on domain decomposition methods, finite element methods,
fast integral equation methods, hybrid methods, and model order
reduction, all in the context of antennas, electromagnetic scattering,
microwave devices, EMC/EMI and optical lithography modeling. Recently he
started working on experimental research in antennas and the design of
ultrawideband and low-profile phased arrays.
Directions and parking:
Meeting is being held at MIT Lincoln Laboratory is located at 244 Wood St., Lexington, MA 02420. The cafeteria is open to the public and visitor parking is available adjacent to the main entrance (in front of the parking structure). The Laboratory is also accessible via MBTA Bus route 76. When entering the Wood St. gate and the Main Cafeteria entrance, please tell the guard on duty that you are a visitor attending the IEEE meeting.
(Thanks to the Boston Photonics Society for the following directions.)
From interstate I-95/Route 128:
Take Exit 31B onto Routes 4/225 towards Bedford - Stay in right lane
Use Right Turning Lane (0.3 mile from exit) to access Hartwell Ave. at 1st Traffic Light.
Follow Hartwell Ave. to Wood St. (~1.3 miles).
Turn Left on to Wood Street and Drive for 0.3 of a mile.
Turn Right into MIT Lincoln Lab, at the Wood Street Gate.
From Exit 30B:
Take Exit 30B on to Route 2A - Stay in right lane.
Turn Right on to Mass. Ave (~ 0.4 miles - opposite Minuteman Tech.).
Follow Mass. Ave for ~ 0.4 miles.
Turn Left on to Wood Street and Drive for 1.0 mile.
Turn Left into MIT Lincoln Lab, at the Wood Street Gate.
To get to the Cafeteria, proceed toward the Main Entrance of Lincoln Laboratory. Before entering the building, proceed down the stairs located to the left of the Main Entrance. Turn right at the bottom of the stairs and enter the building through the Cafeteria entrance. The Cafeteria is located directly ahead.
For additional information, please contact Chris Galbraith (chris.galbraith@ll.mit.edu)
Antenna & Propagation Society
6:00 PM, Tuesday, 17 April
Solution of Extremely Large Integral Equations in Computational Electromagnetics (with Fast Algorithms and Parallel Computing)
Levent Gürel, Professor, Dept. of Electrical and Electronics Engineering, Director, Computational Electromagnetics Research Center (BiLCEM), Bilkent University, Ankara, Turkey
Accurate simulations of real-life electromagnetics problems with integral equations require the solution of dense matrix equations involving millions of unknowns. Solutions of these extremely large problems cannot be achieved easily, even when using the most powerful computers with state-of-the-art technology. Some of the world’s largest integral-equation problems in computational electromagnetics have been solved at Bilkent University Computational Electromagnetics Research Center (BiLCEM). Most recently, we have achieved the solution of 550,000,000x550,000,000 dense matrix equations! This achievement is an outcome of a multidisciplinary study involving physical understanding of electromagnetics problems, novel parallelization strategies (computer science), constructing parallel clusters (computer architecture), advanced mathematical methods for integral equations, fast solvers, iterative methods, preconditioners, and linear algebra.
In this seminar, following a general introduction to our work in computational electromagnetics, I will continue to present fast and accurate solutions of large-scale electromagnetic modeling problems involving three-dimensional geometries with arbitrary shapes using the multilevel fast multipole algorithm (MLFMA) and parallel MLFMA. Some of the complicated real-life problems (such as, scattering from a realistic aircraft) involve geometries that are larger than 1000 wavelengths. Accurate solutions of such problems can be used as reference data for high-frequency techniques. Solutions of extremely large canonical benchmark problems involving sphere and NASA Almond geometries will be presented, in addition to the solution of complicated objects, such as metamaterial problems, red blood cells, and dielectric photonic crystals. Solving the world's largest computational electromagnetics problems has important implications in terms of obtaining the solution of previously intractable physical, real-life, and scientific problems in various areas, such as (subsurface) scattering, optics, bioelectromagnetics, metamaterials, nanotechnology, remote sensing, etc. For more information, please visit www.cem.bilkent.edu.tr.
Prof. Levent Gürel (Fellow of IEEE, ACES, and EMA) is the Director of
the Computational Electromagnetics Research Center (BiLCEM) at Bilkent
University, Ankara, Turkey. He received the M.S. and Ph.D. degrees from
the University of Illinois at Urbana-Champaign (UIUC) in 1988 and 1991,
respectively, in electrical and computer engineering. He joined the IBM
Thomas J. Watson Research Center, Yorktown Heights, New York, in 1991.
Since 1994, he has been a faculty member in the Department of Electrical
and Electronics Engineering of the Bilkent University, Ankara, where he
is currently a Professor, and a Visiting/Adjunct Professor at UIUC since
2003. Among the recognitions of Prof. Gürel's accomplishments, the two
prestigious awards from the Turkish Academy of Sciences (TUBA) in 2002
and the Scientific and Technological Research Council of Turkey
(TUBITAK) in 2003 are the most notable. Prof. Gürel is currently serving
as an associate editor of Radio Science, IEEE Antennas and Wireless
Propagation Letters (AWPL), Journal of Electromagnetic Waves and
Applications (JEMWA), and Progress in Electromagnetics Research (PIER).
He is named an IEEE Distinguished Lecturer for 2011-2013 and invited to
address the 2011 ACES Conference as a Plenary Speaker.
Meeting will be held at MIT Lincoln Laboratory A-Café, 244 Wood Street, Lexington, MA. For directions please see: http://www.ll.mit.edu/about/map.html
For more information, contact Antennas & Propagation chair, Gregory Charvat at Gregory.charvat@ll.mit.edu
Nuclear and Plasma Science, Antennas & Propagation, Communications, Geoscience and Remote Sensing, and Aerospace & Electronic Systems Societies
4:00 PM, *Fridays, April 6, 13, 20, and 27
Controlled study of space plasma turbulence and effects on satellite and radio communications, using radars, GPS satellites, and optical instruments
(Please Note: This a multi-session chapter meeting )
A series of lectures will be delivered for one and half hours each on the subjects of "Controlled study of space plasma turbulence and effects on satellite and radio communications, using radars, GPS satellites, and optical instruments".
Location: Boston University Photonics Center, PHO 211, 8 St. Mary's Street, Boston, MA 02215.
For more information, please contact Min-Chang Lee at mclee@mit.edu