Events

Please join us for an upcoming talk on Apr 13, 3-4 pm (Eastern Time) by Prof. Reyhan Baktur titled "Integrated Solar-Pannel Antennas," as part of the 2021-2022 IEEE AP-S seminar series. Abstract: Conformal Integration of antennas with solar panels has wide applications, from small spacecraft, Mars rovers, to self-powered wireless sensors. It is particularly beneficial when the surface real estate is a major challenge, such as a CubeSat. A strategic integration not only reduces the development cost, promotes a robust communication link, but also increases the mission capacity by allowing more science instruments to be mounted on the CubeSat. This lecture covers different conformal antenna designs for solar panel integration, from UHF to Ka band. It includes antennas integrated under solar cells, around solar cells, and optically transparent antennas integrated on top of solar cells. It also covers low gain and high gain design. The high gain design mainly focuses on reflectarray antenna, which may be beneficial to those who wishes to study the subject. As these antennas are integrated with solar panel, a unique and complex subsystem, effects of solar cells on the antenna and vice versa need to be analyzed and quantified. The lecture presents analysis of a typical space-certified solar cell, extracted model, experimental set-up to quantify the interaction between solar cells and the integrated antennas. About Speaker: Dr. Reyhan Baktur is an associate professor at the department of Electrical and Computer Engineering (ECE), Utah State University (USU). Her research interests include antennas and microwave engineering with a focus on antenna design for CubeSats; optically transparent antennas; multifunctional integrated antennas, sensors, and microwave circuits. She is affiliated with the Center for Space Engineering at USU, the Space Dynamics Laboratory (the university affiliated research center), and collaborates with NASA Goddard Space Flight Center. Dr. Baktur is an AdCom member of IEEE Antennas and Propagation Society, and is active in US National Committee of the International Union of Radio Science, serving as the vice chair for commission B, and the inaugural chair for the Women in Radio Science. She is passionate and committed to electromagnetic education and student recruiting by introducing CubeSat projects in undergraduate classrooms. She is the recipient of the IEEE Antennas and Propagation Society’s (APS) the Donald G. Dudley Jr. Undergraduate Teaching Award in 2013 and has been actively serving IEEE APS student paper competition and student design contest. Dr. Baktur’s lectures will focus on CubeSat Development Basics, Link Budget Analysis and Development, Antenna Designs for CubeSats and Small Satellites, Transparent Antennas, and Class Projects for Electromagnetic Courses

There has been significant research devoted to the development of distributed microwave wireless systems in recent years. The progression from large, single-platform wireless systems to collections of smaller, coordinated systems on separate platforms enables significant benefits for radar, remote sensing, communications, and other applications. The ultimate level of coordination between platforms is at the wavelength level, where separate platforms operate as a coherent distributed system. Wireless coherent distributed systems operate in essence as distributed phased arrays, and the signal gains that can be achieved scale proportionally to the number of transmitters squared multiplied by the number of receivers, providing potentially dramatic increases in wireless system capabilities. Distributed array coordination requires accurate control of the relative electrical states of the nodes. Generally, such control entails wireless frequency synchronization, phase calibration, and time alignment, but for remote sensing operations, phase control also requires high-accuracy knowledge of the relative positions of the nodes in the array to support beamforming. This lecture presents an overview of the challenges involved in distributed phased array coordination, and describes recent progress on microwave technologies that address these challenges. Requirements for achieving distributed phase coherence at microwave frequencies are discussed, including the impact of component non-idealities such as oscillator drift on beamforming performance. Architectures for enabling distributed beamforming are reviewed, along with the relative challenges between transmit and receive beamforming. Microwave and millimeter-wave technologies enabling wireless phase-coherent synchronization are discussed, focusing on technologies for high-accuracy internode ranging, wireless frequency transfer, and high-accuracy time alignment. The lecture concludes with a discussion of open challenges in distributed phased arrays, and where microwave technologies may play a role. Speaker(s): Prof. Jeffrey Nanzer Register: https://events.vtools.ieee.org/m/311733 Biography: Jeffrey Nanzer (S’02-M’08-SM’14) received the B.S. degree in electrical engineering and computer engineering from Michigan State University, East Lansing, MI, USA, in 2003, and the M.S. and Ph.D. degrees in electrical engineering from The University of Texas at Austin, Austin, TX, USA, in 2005 and 2008, respectively. From 2008 to 2009, he was a Postdoctoral Fellow with Applied Research Laboratories, The University of Texas at Austin, where he was involved in designing electrically small HF antennas and communication systems. From 2009 to 2016, he was with The Johns Hopkins University Applied Physics Laboratory, Laurel, MD, USA, where he created and led the Advanced Microwave and Millimeter-Wave Technology Section. In 2016, he joined the Department of Electrical and Computer Engineering, Michigan State University, where he is currently the Dennis P. Nyquist Associate Professor. He has authored or co-authored more than 150 refereed journal and conference papers, authored the book Microwave and Millimeter-Wave Remote Sensing for Security Applications (Artech House, 2012), and co-authored chapters in the books Wireless Transceiver Circuits (Taylor and Francis, 2015) and Short-Range Micro-Motion Sensing: Hardware, signal processing and machine learning (IET, 2019). His current research interests include distributed arrays, radar and remote sensing, antennas, electromagnetics, and microwave photonics. Dr. Nanzer was a founding member and the First Treasurer of the IEEE APS/MTT-S Central Texas Chapter. He is also a member of the IEEE Antennas and Propagation Society Education Committee and the USNC/URSI Commission B. He was a recipient of the Outstanding Young Engineer Award from the IEEE Microwave Theory and Techniques Society in 2019, the DARPA Director’s Fellowship in 2019, the National Science Foundation (NSF) CAREER Award in 2018, the DARPA Young Faculty Award in 2017, and the JHU/APL Outstanding Professional Book Award in 2012. He has served as the Vice-Chair for the IEEE Antenna Standards Committee from 2013 to 2015 and the Chair of the Microwave Systems Technical Committee (MTT-16) of the IEEE Microwave Theory and Techniques Society from 2016 to 2018. He is also an Associate Editor of the IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION.

Adaptive mesh refinement (AMR) is the art of solving PDEs on a mesh hierarchy with increasing mesh refinement at each level of the hierarchy. Accurate treatment on AMR hierarchies requires accurate prolongation of the solution from a coarse mesh to a newly-defined finer mesh. For scalar variables, suitably high order finite volume WENO methods can carry out such a prolongation. However, classes of PDEs, like computational electrodynamics (CED) and magnetohydrodynamics (MHD), require that vector fields preserve a divergence constraint. The primal variables in such schemes consist of normal components of the vector field that are collocated at the faces of the mesh. As a result, the reconstruction and prolongation strategies for divergence constraint-preserving vector fields are necessarily more intricate. In this seminar, we present a fourth order divergence constraint-preserving prolongation strategy that is analytically exact. Extension to higher orders using analytically exact methods is very challenging. To overcome that challenge, a novel WENO-like reconstruction strategy is invented that matches the moments of the vector field in the faces where the vector field components are collocated. This approach is almost divergence constraint-preserving; so we call it WENO-ADP. To make it exactly divergence constraint-preserving, a touch-up procedure is developed that is based on a constrained least squares (CLSQ) based method for restoring the divergence constraint up to machine accuracy. With the touch-up, it is called WENO-ADPT. It is shown that refinement ratios of two and higher can be accommodated. An item of broader interest in this work is that we have also been able to invent very efficient finite volume WENO methods where the coefficients are very easily obtained and the multidimensional smoothness indicators can be expressed as perfect squares. We demonstrate that the divergence constraint-preserving strategy works at several high orders for divergence-free vector fields as well as vector fields where the divergence of the vector field has to match a charge density and its higher moments. We also show that our methods overcome the late time instability that has been known to plague adaptive computations in Computational Electrodynamics. Co-sponsored by: Center for Computational Science and Engineering (CCSE), University of Toronto Speaker(s): Prof. Dinshaw Balsara, Register: https://events.vtools.ieee.org/m/312555 Biography: Dinshaw S. Balsara received the Ph.D. degree in computational physics and astrophysics from the University of Illinois at Urbana-Champaign, Champaign, IL, USA, in 1990. He is currently a Professor with the Department of Physics and the Department of Applied and Computational Mathematics and Statistics at the University of Notre Dame. He has developed computational algorithms and applications in the areas of interstellar medium, turbulence, star formation, planet formation, the physics of accretion disks, compact objects, and relativistic astrophysics. Many of the algorithms developed by him for higher order methods have seen extensive use and have been copiously cited.,Dr. Balsara was the recipient of the 2014 Department of Energy Award of Excellence for significant contributions to the Stockpile Stewardship Program and the 2017 Global Initiative on Academic Networks Award from the Government of India. He serves the community as an Associate Editor of Journal of Computational Physics and Computational Astrophysics and Cosmology.