Serving Eastern Massachusetts
We present a compact dual-linearly polarized ultrawideband (UWB) antenna for continuous transmit-receive operation from 100MHz to 2000MHz. The antenna implements broadband transverse electromagnetic horn antenna concepts for high frequency operation and miniaturized dipole antenna concepts for low frequency operation. The flared horn section closer to the input feed is responsible for radiation above 1000MHz, while the overall radiating elements, including the folded ends, is responsible for radiation below 1000MHz. Bow-tie antenna concepts are implemented for broadband low frequency operation characteristics. The bore-sight realized gain monotonically increases from -15dBi at 90MHz to 0dBi at 600MHz, and remains approximately +4dBi above 1000MHz. The overall antenna fit into a volume package with diameter of 15 inches and height of 6 inches. We achieve antenna miniaturization by means of the Artificial Transmission Line (ATL) method, where the inductance and capacitance on the antenna structure are modified in a transmission line sense. Ferrite absorber treatment on the ground plane is also used to produce a compact antenna design. The antenna is designed such that linearly polarized fields can be radiated from two orthogonal antenna elements. This antenna is suitable for software-defined radio applications.
Idahosa A. Osaretin (S’07–M’11) received a B.S. in Electrical and Computer Engineering in 2006, M.S. in Electrical Engineering in 2010, and Ph.D. in Electrical Engineering in 2011, all from the Ohio State University, Columbus OH. Since 2011, he has worked at MIT Lincoln Laboratory where he is currently a member of the Technical Staff. His current research interests include microwave radiometer design and analysis, compact reflector antenna design, compact and wideband horn feeds for reflector antennas, low profile ultra-wide band antenna design and analysis, microwave circuits, and electromagnetic wave propagation (radiation, scattering, and wave-guiding) in complex environments.
Meeting will be held in MIT Lincoln Laboratory A-Café . Refreshments served at 5:30pm
For more information, contact Antennas & Propagation chair, Raoul O. Ouedraogo, firstname.lastname@example.org
For directions please see: http://www.ll.mit.edu/about/map.html
It is well known that electrically small (size to be much smaller than the wavelength at the operating carrier frequency), passive antennas suffer from fundamental limitations on achievable bandwidths. The bandwidth of electrically small antennas could, however, be substantially improved by incorporating lossy matching networks. But this will be at the cost of significantly higher power dissipation in the matching networks, which will tend to decrease the overall radiation efficiency. If, on the other hand, the antenna currents could somehow be made to change rapidly at a rate directly dictated by the message signal, then there is no difficulty in radiating such a rapidly varying waveform from the induced antenna currents, despite its narrow input impedance bandwidth.
In this talk we discuss the theory of operation of a linear, electrically small, time-varying antenna by considering a thin dipole loaded with a fast switching element. Time-variation of antenna structure is achieved by operating the switch via a message signal that has the overall effect of transferring a modulated carrier to antenna currents for subsequent radiation.
Time-domain integral equation and linear state-space theory is used to understand the dynamics of the radiated waveform and the antenna input current. It is demonstrated that the antenna has capabilities of radiating waveforms with an information bandwidth that is an order of magnitude greater than possible with an electrically small traditional antenna. Effect of switch parameters such as the finite OFF resistance and finite switching times relative to the time period of the RF carrier on the operation of the antenna are also presented.
Bio: Ramakrishna Janaswamy received his Ph.D. degree in electrical engineering in 1986 from the University of Massachusetts, Amherst. He received his Master’s degree in Microwave and Radar Engineering from IIT-Kharagpur, India in 1983 and the Bachelor’s degree in Electronics and Communications Engineering from REC-Warangal (now NITWarangal), India in 1981. From August 1986 to May 1987, he was an Assistant Professor of electrical engineering at Wilkes University, Wilkes Barre, PA. From August 1987-August 2001 he was on the faculty of the Department of Electrical and Computer Engineering, Naval Postgraduate School, Monterey, CA. In September 2001 he joined the Department of Electrical & Computer Engineering, University of Massachusetts, Amherst, where he is a currently a Professor. He was a visiting researcher at the Center for PersonKommunikation, Aalborg, Denmark from September 1997 to June 1998 and spent the Summers of 1994 and 1995 at SPAWARSYSCEN, San Diego, California and NASA Ames Research Center, Moffett Field, California, respectively. His research interests include deterministic and stochastic radio wave propagation modeling, analytical and computational electromagnetics, antenna theory and design, and wireless communications. His research is/was funded by several agencies such as NSF, ONR, ARO, and several Department of Navy laboratories. His personal hobbies include birdwatching and wildlife photography.
Rama Janaswamy is a Fellow of IEEE and was the recipient of the R. W. P. King Prize Paper Award of the IEEE Transactions on Antennas and Propagation in 1995. For his services to the IEEE Monterey Bay Subsection, he received the IEEE 3rd Millennium Medal from the Santa Clara Valley Section in 2000. He is an elected member of U.S. National Committee of International Union of Radio Science, Commissions B and F. He served as an Associate Editor of Radio Science from January 1999-January 2004 and Associate Editor of IEEE Transactions on Vehicular Technology from 2003-2006. He is currently an Associate Editor of IEEE Transactions on Antennas and Propagation and of the IETE (India) Technical Reviews. He is the author of the book Radiowave Propagation and Smart Antennas for Wireless Communications, Kluwer Academic Publishers, November 2000 and a contributing author in Handbook of Antennas in Wireless Communications, L. Godara (Ed.), CRC Press, August 2001 and Encyclopedia of RF and Microwave Engineering, K. Chang (Ed.), John Wiley & Sons, 2005.
Raoul O. Ouedraogo, email@example.com or
Wajih Elsallal, firstname.lastname@example.org, Phone:(319) 775-5296
Foreign nationals should RSVP by contacting Wajih Elsallal no later than 5/15/2014
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opic: Operating Electrically Small Antennas for High Information Bandwidths
Date: Tuesday, May 20, 2014
Time: 3:00 pm, Eastern Daylight Time (New York, GMT-04:00)
Meeting Number: 596 891 596
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Conference Code: 796 395 4371
The coexistence of electric polarization and magnetization in multiferroic materials provides great opportunities for realizing magnetoelectric coupling, including electric field control of magnetism, or vice versa, through a strain mediated magnetoelectric interaction effect in layered magnetic/ferroelectric multiferroic heterostructures [1-7]. Strong magnetoelectric coupling has been the enabling factor for different multiferroic devices, which however has been elusive, particularly at RF/microwave frequencies. In this presentation, I will cover the most recent progress on novel layered microwave multiferroic heterostructures and devices, which exhibit strong magnetoelectric coupling. We will demonstrate strong magnetoelectric coupling in novel microwave multiferroic heterostructures. These multiferroic heterostructures exhibit a giant voltage tunable magnetic field of 3500 Oe, and a high electrostatically tunable ferromagnetic resonance frequency range between 1.75~ 7.57 GHz, a tunable frequency of 5.82 GHz or fmax/fmin=4.3 [2,3]. At the same time, we will demonstrate E-field modulation of anisotropic magnetoresistance, giant magnetoresistance and exchange bias at room temperature in different multiferroic heterostructures . New multiferroic devices will also be covered in the talk, including ultra-sensitive nanoelectromechanical systems magnetoelectric sensors with picoTesla sensitivity , multiferroic voltage tunable bandpass filters , voltage tunable inductors , tunable bandstop filters, tunable phase shifters and spintronics, etc.
1. N.X. Sun and G. Srinivasan, SPIN, 02, 1240004 (2012); 2. J. Lou, et al., Advanced Materials, 21, 4711 (2009); 3. . J. Lou, et al. Appl. Phys. Lett. 94, 112508 (2009) 4; M. Liu, et al. Advanced Functional Materials, 21, 2593 (2011); 5. T. Nan, et al. Scientific Reports, 3, 1985 (2013); 6. M. Liu, et al. Advanced Materials, 25, 1435 (2013); 7 M. Liu, et al. Advanced Functional Materials, 19, 1826 (2009).
Nian Sun is an associate professor at the Electrical and Computer Engineering Department, Northeastern University. He received his Ph.D. degree from Stanford University. Prior to joining Northeastern University, he was a Scientist at IBM and Hitachi Global Storage Technologies. Dr. Sun was the recipient of the NSF CAREER Award, ONR Young Investigator Award, the Søren Buus Outstanding Research Award, etc. His research interests include novel magnetic, ferroelectric and multiferroic materials, devices and subsystems. He has over 150 publications and over 20 patents and patent disclosures. One of his papers was selected as the “ten most outstanding full papers in the past decade (2001~2010) in Advanced Functional Materials”. Dr. Sun has given over 70 invited or keynote presentations in national and international conferences and universities. He is an editor of IEEE Transactions on Magnetics, and a fellow of the Institute of Physics and of the Institution of Engineering and Technology.
Refreshments will be served at 5:30PM at Northeastern University, Burlington Campus: Kostas Research Institute for Homeland Security, 141 South Bedford Street, Burlington, MA 01803.
Registration is encouraged https://meetings.vtools.ieee.org/meeting_view/list_meeting/24217