Electromagnetics & Radiation

Silicon-based Terahertz systems is a field that is only about a decade old. In this time, we have seen a phenomenal growth of silicon systems operating at THz frequencies for a wide range of applications in sensing, imaging and communication. It can be argued that both the ‘THz gap’ and the ‘technology and applications gap’ is closing in meaningful ways in the THz range. Technologies beyond 100 GHz focusing on sensing, imaging and wireless back-haul links are getting attractive as we enter into a new area of highly dense network of autonomous systems requiring ultra-high speed and reliable links. In order to move beyond this inflection point as Moore’s law continue to slow, I will discuss why we need to look beyond the classical ‘device’-level metrics of efficiency and sensitivity of THz sources and detectors towards holistic ‘system’ level properties such as scalability and programmability. Such properties are critically important for applications in sensing and imaging, as evidenced across sensor fusion technologies across mmWave, IR and optical frequencies. In this talk, I will highlight approaches that cut across electromagnetics, circuits, systems and signal processing, to allow for such reconfigurability in THz signal synthesis and sensing, yet realized with devices that are themselves not very efficient. Particularly, we will demonstrate approaches to THz beamforming arrays, CMOS sensors reconfigurable across the three field properties of spectrum (100 GHz-1000 GHz), beam pattern and polarization (Nature Comm’19), programmable THz metasurfaces with CMOS tiling (Nature Elec’20), and enabling dynamic spectrum shaping (ISSCC’21, JSSC’21) and physically secure sub-THz links (ISSCC’20, Nature Elec’21). In the end, I will comment on what could be the major directions for the field in the coming decade. Speaker(s): Kaushik Sengupta, Room: BA1230, Bldg: Bahen Center for Information Technology, 40 St George St, Toronto, Ontario, Canada

IEEE Antennas and Propagation Society (AP-S) Distinguished Lecture Please join us for an upcoming lecture on 27 Apr. 2023 at 11 am – 12 pm (Eastern Time) by Prof. Reyhan Baktur, from Utah State University, USA. Overview of CubeSats: from Concept to Orbit CubeSats are modular and standardized modern small satellites. They have been gaining steady popularity as educational projects, low-cost space exploration vehicles for technology demonstrations, multi-point observations of space environment, and monitoring/reporting proper deployment of expensive deep space instruments. With rapid advancement of electronics, novel mechanical design, and aerospace technology, new progress in CubeSats is emerging every day. This calls for interests and early involvements of creative young minds. The objective of this presentation is to convey the basics of CubeSat development cycle, launch methods, typical CubeSat orbits, link budget analysis, various antenna solutions, and feasible classroom projects. For the interests of young professionals in electrical engineering, this lecture features a tour of several recent CubeSat missions and antenna designs for spacecraft, ground station, and radio beacon. Biography 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 an IEEE Antennas and Propagation (APS) Distinguished Lecturer of 2022-2024, AdCom member of IEEE APS, 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. Co-sponsored by: Toronto Metropolitan University Speaker(s): Reyhan Baktur, Room: EPH 225, Bldg: Eric Pallin Hall, Toronto Metropolitan University (formerly Ryerson University), 87 Gerrard St East, Toronto, Ontario, Canada

Join the IEEE Toronto Electromagnetics & Radiation Society Chapter for a talk on High Order Adaptive Mesh Refinement, presented by Professor Dinshaw S. Balsara. Abstract: 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 talk, 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, University of Toronto Speaker(s): Prof. D. S. Balsara, Register: https://events.vtools.ieee.org/m/312557 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. 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.