Levent Sevgi of OKAN University, Turkey

EM diffraction is critical in many applications including antennas and propagation. Understanding and visualizing EM wave – object interaction is crucial in designing new antenna systems, in predicting path losses through complex propagation paths, etc. In order to do that wave pieces such as diffracted waves, Fringe waves, etc., should first be studied on canonical structures. Then, complex objects can be investigated by using HFA as well as numerical methods in hybrid form intelligently.

EM wave scattering from waves – objects interaction has long been investigated. Interesting wave phenomena, diffraction, occur when objects have sharp edges and tips. Methods known as High Frequency Asymptotics, such as Geometric optics (GO), Physical Optics, (PO), Geometrical Theory of Diffraction, (GTD), Uniform Theory of Diffraction (UTD), Physical Theory of Diffraction (PTD) and Theory of Edge Diffraction (TED) have been successfully applied to variety of EM problems. Recently, numerical methods, such as Finite Difference time Domain (FDTD), Method of Moments (MoM) and Finite Element Method (FEM) have also been used in modeling EM diffraction. These powerful methods, together with novel approaches, have shown to be successful not only in modeling EM diffraction but also in distinguishing wave pieces such as scattered waves, diffracted waves, Fringe waves, etc., which is very important in visualizing and understanding complex wave – object interaction.  

This seminar will review all these approaches, use recently developed EM virtual tools and present comparisons through canonical examples.

References

• Sevgi, Electromagnetic Modeling and Simulation, IEEE Press – John Wiley (EM Wave Series), NJ, Apr 2014.
• Sevgi, Complex Electromagnetic Problems and Numerical Simulation Approaches, IEEE Press – John Wiley & Sons, May 2003.
• Apaydın, L. Sevgi, Electromagnetic Diffraction modeling and simulation with MATLAB, ARTECH House, Norwood, MA, Feb 2021.
• Balanis, L. Sevgi, P. Ya Ufimtsev, “Fifty Years of High Frequency Asymptotics,” RFMiCAE, International Journal on RF and Microwave Computer-Aided Engineering, 23 (4), Jul 2013, pp.394–402.
• Hacıvelioğlu, L. Sevgi, P. Ya. Ufimtsev, “Electromagnetic Wave Scattering from a Wedge with Perfectly Reflecting Boundaries: Analysis of Asymptotic Techniques,” IEEE Antennas and Propagation Magazine, Vol. 53, No. 3, pp.232-253, Jun 2011.
• Hacıvelioğlu, M. A. Uslu, L. Sevgi, “A Matlab-based Virtual Tool for the Electromagnetic Wave Scattering from a Perfectly Reflecting Wedge”, IEEE Antennas and Propagation Magazine, 53 (6), Dec 2011, pp.234–243.
• Çakır, L. Sevgi, P. Ya. Ufimtsev, “FDTD Modeling of Electromagnetic Wave Scattering from a Wedge with Perfectly Reflecting Boundaries: Comparisons against Analytical Models and Calibration,” IEEE Trans. on Antennas and Propagat., 60 (7), Jul 2012, pp. 3336–3342.
• A. Uslu, L. Sevgi, “Matlab-based Virtual Wedge Scattering Tool for the Comparison of High Frequency Asymptotics and FDTD Method”, ACES Journal, 27 (9), 2012, pp.697–705.
• Apaydın, L. Sevgi, “Method of Moments (MoM) Modeling of Wave Propagation inside a Wedge Waveguide,” ACES Journal, 29 (8), 2014, pp.515–522.

Biography:

Prof. Dr. Levent Sevgi is a Fellow of the IEEE. He received his B. Eng., M. Eng., and PhD degrees in Electronic Engineering from Istanbul Technical University (ITU) in 1982, 1984 and 1990, respectively. In 1987, while working on his PhD, he was awarded a fellowship that allowed him to work with Prof. L. B. Felsen at Weber Research Institute / New York Polytechnic University York for two years. His work at the Polytechnic concerned the propagation phenomena in non-homogeneous open and closed waveguides.

He was with Istanbul Technical University (1991–1998), TUBITAK-MRC, Information Technologies Research Institute (1999–2000), Weber Research Institute / NY Polytechnic University (1988–1990), Scientific Research Group of Raytheon Systems Canada (1998 – 1999), Center for Defense Studies, ITUV-SAM (1993 –1998 and 2000–2002) and with University of Massachusetts, Lowell (UML) MA/USA as a full-time faculty (2012 – 2013) and with DOGUS University (2001-2014). Since Sep 2014, he has been with Istanbul OKAN University.

He has been an IEEE AP-S Distinguished Lecturer for the term 2020-2022. He served one-term in the IEEE AP-S AdCom (2013-2015) and one-term and as a member of IEEE AP-S Field Award Committee (2018-2019). He has been the writer/editor of the “Testing ourselves” Column in the IEEE AP Magazine (since Feb 2007), a member of the IEEE AP-S Education Committee (since 2006), He has also served in several editorial boards (EB) of other prestigious journals / magazines, such as the IEEE AP Magazine (since 2007), Wiley’s International Journal of RFMiCAE (2002-2018), and the IEEE Access (2017-2019 and 2020 - 2022). He is the founding chair of the EMC TURKIYE International Conferences (www.emcturkiye.org).

He has been involved with complex electromagnetic problems and complex communication and radar systems for nearly three decades. His research study has focused on propagation in complex environments; electromagnetic scattering and diffraction; RCS prediction and reduction; EMC/EMI modelling, simulation, tests and measurements; multi-sensor integrated wide area surveillance systems; surface wave HF radars; analytical and numerical methods in electromagnetics; FDTD, TLM, FEM, SSPE, and MoM techniques and their applications; bio-electromagnetics. He is also interested in novel approaches in engineering education, teaching electromagnetics via virtual tools. He also teaches popular science lectures such as Science, Technology and Society.

He has given dozens of seminars, invited/keynote talks, organized/presented several tutorials, training sessions and short courses from half-day to three-days in universities/institutes all around the World. He has published more than a dozen special issues / sections in many journals as a guest editor and/or a co-guest editor.

His recent keynote talks are: (i) From Engineering Electromagnetics towards Electromagnetic Engineering: Teaching, Training Next Generations in MMS’2018 Mediterranean Microwave Symposium, Istanbul / Turkey, and in EuCAP 2019 European Conference on Antennas and Propagation, Krakow / Poland, (ii) Radiowave Propagation Modeling and Simulation in APCAP 2019 Asia-Pasific Conference on Antennas and Propagation, Incheon / S. Korea, and (iii) From Design to Market: EMC Engineering in InCAP 2018 Indian Conference on Antennas and Propagation, Hyderabad / India.

He has published many books/book chapters in English and Turkish, over 180 journal/magazine papers/tutorials and attended nearly 100 international conferences/symposiums. His three books Complex Electromagnetic Problems and Numerical Simulation Approaches, Electromagnetic Modeling and Simulation and Radiowave Propagation and Parabolic Equation Modeling were published by the IEEE Press - WILEY in 2003, 2014, and 2017, respectively. His fourth and fifth books, A Practical Guide to EMC Engineering (Sep 2017) and Diffraction Modeling and Simulation with MATLAB (Feb 2021) were published by ARTECH HOUSE.

His h-index is 35, with a record of more than 4100 citations (source: Google Scholar, July 2021).

Email: