TEACHING ELECTROMAGNETICS VIRTUAL TOOLS

Transcription

1 TEACHING ELECTROMAGNETICS via VIRTUAL TOOLS Levent SEVGİ OKAN University Faculty of Engineering & Architecture Electrical Electronics Engineering Dept Tuzla Campus, AKFIRAT, Tuzla / ISTANBUL ; ls@leventsevgi.net Copyright The use of this work is restricted solely for academic purposes. The author of this work owns the copyright and no reproduction in any form is permitted without written permission by the author. 1

2 Biography Prof. Dr. Levent Sevgi Born in Akhisar / Turkey on 1st January He received his BsEE, MsEE 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 ( ), TUBITAK-MRC, Information Technologies Research Institute ( ), Weber Research Institute/Polytechnic University in New York / USA ( ), Scientific Research Group of Raytheon Systems, Canada ( ), Center for Defense Studies, ITUV-SAM ( and ) and with University of Massachusetts, Lowell (UML) MA/USA as a full-time faculty ( ) and with Doğuş University ( ). Since Sep 2014, he has been with Okan University. 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, analytical and numerical methods in electromagnetic, EMC/EMI modeling and measurement, communication, radar and integrated surveillance systems, surface wave HF radars, FDTD, TLM, FEM, SSPE, and MoM techniques and their applications, RCS modeling, bioelectromagnetics. 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 is a Fellow member of the IEEE, an AdCom member of the IEEE Antennas and Propagation Society ( ), the writer/editor of the Testing ourselves Column in the IEEE Antennas and Propagation Magazine (since Feb 2007) and a member of the IEEE Antennas and Propagation Society Education Committee (since Jun 2006). He is also a member of several editorial boards (EB), such as the IEEE Antennas and Propagation Magazine (since 2007), the IEEE Access ( ), Wiley s International Journal of RFMiCAE (since 2002), etc. He has published many books/book chapters in English and Turkish, over 170 journal/magazine papers/tutorials and attended nearly 100 international conferences/symposiums. His two books "Complex Electromagnetic Problems and Numerical Simulation Approaches" and "Electromagnetic Modeling and Simulation" were published by the IEEE Press - Wiley in 2003 and 2014, respectively. His third book, A Practical Guide to EMC Engineering was published by ARTECH House (Norwood/MA, USA and London, UK) in March His fourth book Guided Wave Propagation and Parabolic Equation Modeling with Gökhan Apaydın will be published by the IEEE Press - Wiley around Oct

3 Abstract Virtual tool based novel teaching methods in electromagnetic will be discussed. Fundamental concepts, such as modeling and simulation, analytical- and numerical-based modeling, simulation, validation, verification, etc., in relation to the virtual labs widely-covered as parts of engineering education will be reviewed. Sample virtual tools that can be used in basic as well as advanced level courses will be shown. Index Terms: virtual tool Summary We have witnessed a transformation from ENGINERING ELECTROMAGNETICS to ELECTROMAGNETIC ENGINEERING for the last couple of decades, therefore virtual labs and tools have become attractive in education and training. The overall effectiveness is very positive and the impact on students is that they are better equipped to understand physics and use mathematics. Several user friendly electromagnetic virtual tools have been introduced together with useful tutorials in the IEEE AP Magazine. The IEEE motto Teach me I ll forget, show me, I ll remember, involve me, I ll understand is best expressed with these tools. 3

4 Motivation Question 1: How do you teach electromagnetics to students well above the average (within top 0.1 %)? within top 10 %? around the average? or, well below the average? Question 2: Is it possible to teach all using the same methods / approaches? Engineering and EM Teaching WE ARE ENGINEERS. WE DEAL WITH PHYSICS WE USE MATH WE ALSO USE COMPUTER 4

5 EM Teaching and MODSIM Physics-based Analytical Modeling Conceptual Validity Real-World Problem Data Analysis Numerical and physical Experimentation Operational Validity A Conceptual Model Code Verification Computer Programming A Computer Model EM Problems & Classical Approaches Antenna and Radiation Problems: Use Maxwell equations and BCs Define and Use Auxillary scalar and Vector Potential functions Then derive electric and magnetic fields. Radar Cross Section (RCS) and Scattering Problems: Use Maxwell equations and BCs Represent total fields in terms of incident and scattered fields Send an incident field on to the object, satisfy the BCs Then calculate l the scattered fields. Guided Wave Propagation Problems: Use Maxwell equations and BCs Apply Transverse & Longitudinal decomposition Deal with Eigenvalue and/or Green s function Problems. 5

6 Model based Approach ANALYTICAL NUMERICAL GEOMETRY CIRCUIT ANALYTICAL MODEL USER DATA COMPUTER CODE NUMERICAL RESULT GEOMETRY CIRCUIT COMPUTER CODE NUMERICAL RESULT NUMERICAL MODEL You solve your problem! Computer only gives you a result! You discretize your problem Computer solves it for you! EM Virtual Tools leventsevgi.net 6

7 EM Virtual Tools More than 20 VTools in the last decade Teaching Electromagnetics Basic level Virtual Tools Undergraduate Courses EM Virtual Tool Purpose D FFT A virtual FFT instrument EM prepared Wave with the Theory LabVIEW. It can generate and display time and frequency domain behaviors of sinusoids, a rectangular pulse, a pulse train, a Gaussian Transmission function, a sine modulated Line Theory Gaussian function. 1DFDTD AMatlab based FDTD simulation of plane wave propagation in time domain through single, double or Antennas three layer media. and Propagation TDRMETER A virtual time domain reflectometer virtual tool used to locate/identify faults in all types of metallic paired Electromagnetic cable. Fourier/Laplace analysis Compatibility is also possible. RAY / MODE Ray/mode representations Computational inside a parallel plate non penetrable Electromagnetics waveguide. HYBRID* RAY computes/displays eigenray trajectories between specified source/observer locations. HYBRID displaysfieldvs. range and/or height. DiSLAB A Matlab package designed to investigate wave propagation through a 2D dielectric waveguide based on analytical and numerical formulations. ARRAY A simple Matlab antenna array package of isotropic radiators accommodated with beam forming and beam steering capabilities. MGL 2D A general purpose 2D FDTD package for both TE and TM type problems. Any 2D scenario may be created by the user by just using the PC mouse. SNELL A simple Matlab package for the visualization of ray contributions between a source/receiver pair above a 2D ground using the ray shooting technique. 7

8 Teaching Electromagnetics Advanced Level EM Virtual Graduate Purpose Courses Tool WEDGE A Matlab package for the exploration of wave propagation inside a 2D non penetrable, homogeneously filled wedge waveguide. It investigates line source excited wave fields in terms of EMModeling Modeling and Simulation normal/adiabatic/intrinsic modes. DRMIX AMatlab based package prepared for the mixed path path loss predictions. The effects of the Diffraction Theory number of multi mixed paths, path lengths, electrical parameters, and the frequency can be investigated. Radiowave Propagation Modeling GrSSPE A simple Matlab groundwave propagation package for the visualization of EM propagation over nonflat terrain through non homogeneous atmosphere, for waves radiated by a horizontal antenna over and Simulation the ground. GrMoMPE A Matlab package which modifies MoM method by the application of forward backward spectral Microstrip Circuit Design and acceleration (FBSA) technique and integrate it with the SSPE method. Precise SSPE vs. MoM comparisons are possible. Simulation MSTRIP An FDTD based EM simulator for the broadband investigation of microstrip circuits. The user only needs to picture the microstrip circuit via computer mouse on a rectangular grid, to specify basic RCS Prediction and Reduction dimensions and operational needs such as the frequency band, simulation length. MGL RCS An FDTD based EM simulator for RCS prediction. The user locates a 3D image file of the target in 3DS Guided Wave Theory graphics format, specify user parameters. The simulator predicts RCS vs. angle and/or RCS vs. frequency. MGL MTM A general purpose 2D FDTD package for metamaterial structures. Any 2D geometry can be created by the user by just using the PC mouse. WedgeDIFF High Frequency asymptotics (GO,GTD,UTD,PO,PTD) and FDTD for the diffraction at an semi infinite WedgeFDTD wedge problem. Teaching Electromagnetics EM Modeling and Simulation 2014 L. Sevgi, Teaching Electromagnetic Modeling and Simulation as a Graduate Level Course, IEEE Antennas and Propagation Magazine, Vol. 54, No. 5, pp , Oct E. Arvas, L. Sevgi, A Tutorial on the Method of Moments, IEEE Antennas and Propagation Magazine, Vol. 54, No. 3, pp , Jun G. Apaydin, L. Sevgi, A Canonical Test Problem for Computational Electromagnetics (CEM): Propagation in a Parallel Plate Waveguide IEEE Antennas and Propagation Magazine, Vol. 54, No. 4, pp , Aug

9 Teaching Electromagnetics Radiowave Propagation 2005 SSPE_GUI L. Sevgi, Ç. Uluışık, F. Akleman, "A Matlab based Mtlbb dtwo dimensional i Parabolic Equation Radiowave Propagation Package", IEEE Antennas and Propagation Magazine, Vol. 47, No. 4, , Aug DrMIX_GUI L. Sevgi, "A Mixed Path Groundwave Field Strength Prediction Virtual Tool for Digital Radio Broadcast Systems in Medium and Short Wave Bands", IEEE Antennas and Propagation Magazine, Vol. 48, No. 4, pp.19 27, Aug GrMoMPE F. Akleman, L. Sevgi, "A Novel MoM and SSPE based Groundwave Propagation Field Strength Prediction Simulator", IEEE Antennas and Propagation Magazine, Vol. 49, No. 5, pp.69 82, Oct PETOOL O. Ozgun, G. Apaydin, M. Kuzuoglu, L. Sevgi, PETOOL: MATLAB based One Way and Two Way Split Step Parabolic Equation Tool for Radiowave Propagation over Variable Terrain, Computer Physics Communications (CPC), Elsevier, 182, 2011, pp Teaching Electromagnetics RCS Prediction and Reduction 2008 MGL RCS Ç. Uluışık, G. Çakır, M. Çakır, L. Sevgi, "Radar Cross section (RCS) Modeling and Simulation: Part I Definitions, Strategies, and Canonical Examples ", IEEE Antennas and Propagation Magazine, Vol. 50, No. 1, pp , Feb 2008 G. Çakır, M. Çakır, L. Sevgi, "Radar Cross section (RCS) Modeling and Simulation: Part II A Novel FDTD Based RCS Prediction Virtual Tool ", IEEE Antennas and Propagation Magazine, Vol. 50, No. 2, pp.81 84, Apr FastRCS G. Cakır, M. Cakır, L. Sevgi, An FDTD based Parallel Virtual Tool for the RCS Calculations of Complex Targets, IEEE Antennas and Propagation Magazine, Vol. 56, No.5, pp.74 90, Oct

10 Teaching Electromagnetics Diffraction Theory 2011 WedgeGUI F. Hacıvelioğlu, M. A. Ul Uslu, L. Sevgi, A Matlab based b dsimulator for the Electromagnetic Wave Scattering from a Wedge with Perfectly Reflecting Boundaries, IEEE Antennas and Propagation Magazine, Vol. 53, No. 6, pp , Dec WedgeFDTD M. A. Uslu, L. Sevgi, Matlab Based Virtual Wedge Scattering Tool for the Comparison of High Frequency Asymptotics and FDTD Method, ACES, Int Journal on Applied Computational Electromagnetics, Vol. 27, No. 9, pp , Sep WedgeTOOL A. Uslu, G. Apaydin, L. Sevgi, Work in Progress: Teaching EM Diffraction via Virtual Tools: The WedgeTOOL, EDUCON 2015, Mar 18 20, 2015, Tallinn Estonia F. 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 , Jun Teaching Electromagnetics Microstrip Circuit Design and Simulation 2006 TDRMETER_GUI L. Sevgi, Ç. Uluışık, "A Matlab based Transmission Line Virtual Tool: Finite Difference time Domain Reflectometer", IEEE Antennas and Propagation Magazine, Vol. 48, No.1, pp , Feb FilterDesigner A. Uslu, L. Sevgi, Matlab based Filter Design Program: From Lumped Elements to Microstriplines, IEEE Antennas and Propagation Magazine, Vol. 53, No. 1, pp , Feb MSTRIP G. Çakır, M. Çakır, L. Sevgi, "A Novel Virtual FDTD based Microstrip Circuit Design and Analysis Tool", IEEE Antennas and Propagation Magazine, Vol. 48, No. 6, pp , Dec

11 Teaching Electromagnetics Guided Wave Theory 2004 RAY MODE / HYBRID_GUI L. B. Felsen, F. Akleman, L. Sevgi, "Wave Propagation Inside a Two dimensional Perfectly Conducting Parallel Plate Waveguide: Hybrid Ray Mode Techniques and Their Visualisations", IEEE Antennas and Propagation Magazine, Vol. 46, No.6, pp.69 89, Dec 2004 (Kamel Felsen paper, IEEE TAP Jul 1981) 2007 WEDGE GUI L. Sevgi, F. Akleman, L. B. Felsen, "Visualizations of Wave Dynamics in a Wedge waveguide with non penetrable Boundaries: Normal, Adiabatic, and Intrinsic i Mode Representations", IEEE Antennas and Propagation Magazine, Vol. 49, No. 3, pp.76 94, Jun 2007 G. Apaydin, L. Sevgi, A Canonical Test Problem for Computational Electromagnetics (CEM): Propagation in a Parallel Plate Waveguide IEEE Antennas and Propagation Magazine, Vol. 54, No. 4, pp , Aug The philosophy and Tips EMVtools should be useful and give physical insight. EMVtools should be very user friendly (simple to use). The user should be able to change some parameters. Some parameters should be fixed so that the user will not get lost. It should be open to non physical results to some extend so that the user may commend on them. 11

12 EMVTools: Generic Design Front Panel The Structure Discretization Parameters Operational Parameters VISUALISATION PANEL VT 1: PPlate 12

13 VT 1: PPlate x PEC Postulate the problem y 0 z 2 2 n k a 2 PEC The Green s function associated with this problem is: k g( x, z; x', z' ) ( x x' ) ( z z' ) 2 2 x z and the Green s function may be obtained as j z z n e g( x, z; x', z' ) n a 2 j + g 0 at x 0, a Lim g( x, z; x', z' ) 0 z n x n x' Sin Sin a a VT 1: PPlate 1 m = 1 m = 3 m = Mode solution Plate height (a) Mode profiles Mode solution is the addition of all excited modes using source based excitation coefficients. 13

14 VT 1: PPlate Ray solution Ray solution is the addition of all the contributions of eigenrays. VT 2: Array Feb

15 VT 3: Snell Aug 2004 VT 4: GRMoMPE L. Sevgi Oct 2007 July 22,

16 VT 4: GRMoMPE VT 6: FeMix 16

17 VT 6: FeMix VT 7: MGL 2D 17

18 VT 7: MGL 2D MGL 2D Indoor Propagation VT 7: MGL 2D MGL 2D Outdoor Propagation 18

19 VT 8: MTM FDTD n= 1 n= 2 n=2 n= 3 VT 9: WedgeGUI 19

20 VT 10: WedgeFDTD SBC VT 10: WedgeFDTD Total fields Diff fields 20

21 VT 10: WedgeFDTD Total fields Scattered ields VT 11: MsFilterDesigner 21

22 VT 12: FastRCC VT 12: FastRCC RCS Modeling 22

23 VT 12: FastRCC RCS Modeling =90, =0 RCS Modeling 1. Run FDTD 2. Run FFT VT 12: FastRCC 3. Plot RCS vs. Angle 23

24 VT 13: MSTRIP VT 13: MSTRIP FDTD: Microstriplines Port 2 Source+ Port 1 24

25 VT 13: MSTRIP FDTD: Microstriplines Power Divider VT 13: MSTRIP FDTD: Microstriplines EBG filters 25

26 References [1] L. Sevgi, Electromagnetic Modeling and Simulation, IEEE Press John Wiley (EM Wave Series), NJ, Apr 214. [2] L. Sevgi, Teaching Electromagnetic Modeling and Simulation as a Graduate-Level Course, IEEE Antennas and Propagation Magazine, vol. 54, no. 5, Oct 2012, pp [3] L. Sevgi, Virtual Tools/Labs in Electrical Engineering Education, ELEKTRIK, Turkish J. of Electrical Engineering and Computer Sciences (Special issue on Electrical and Computer Engineering Education in the 21st Century: Issues, Perspectives and Challenges), vol. 14, no. 1, 2006, pp., [4] Visit for the virtual tools discussed here. [5] L. B. Felsen, F. Akleman, L. Sevgi, "Wave Propagation Inside a Two- dimensional Perfectly Conducting Parallel Plate Waveguide: Hybrid Ray-Mode Techniques and Their Visualisations, IEEE Antennas and Propagation Magazine, vol. 46, no.6, Dec 2004, pp [6] L. Sevgi, A Ray shooting Visualisation Matlab Package for 2D Groundwave Propagation Simulations, IEEE Antennas and Propagation Magazine, vol. 46, no 4, Aug 2004, pp [7] L. Sevgi, Ç. Uluışık, A MATLAB-based Visualization Package for Planar Arrays of Isotropic Radiators, IEEE Antennas and Propagation Magazine, 47 (1), Feb 2005, pp [8] L. Sevgi, Ç. Uluışık, A Matlab-based Transmission Line Virtual Tool: Finite-Difference time-domain Reflectometer, IEEE Antennas and Propagation Magazine, vol. 48, no 1, Feb 2006, pp [9] G. Çakır, M. Çakır, L. Sevgi, "A Multipurpose FDTD-Based Two Dimensional Electromagnetic Virtual Tool, IEEE Antennas and Propagation Magazine, vol. 48, no.4, Aug 2006, pp [10] M. Çakır, G. Çakır, L. Sevgi, A Two-dimensional FDTD-based Virtual Metamaterial - Wave Interaction Visualization Tool, IEEE Antennas and Propagation Magazine, vol. 50, no. 3, Jun 2008, pp [11] L. Sevgi, F. Akleman, L. B. Felsen, "Visualizations of Wave Dynamics in a Wedgewaveguide with non-penetrable Boundaries: Normal, Adiabatic, and Intrinsic Mode Representations, IEEE Antennas and Propagation Magazine, vol. 49, no.3, Jun 2007, pp [12] F. 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, vol.53, no. 6, Dec 2011, pp [13] M. A. Uslu, L. Sevgi, Matlab-based Virtual Wedge Scattering Tool for the Comparison of High Frequency Asymptotics and FDTD Method, ACES Journal, vol. 27, no. 9, 2012, pp [14] F. Akleman, L. Sevgi, "A Novel MoM- and SSPE-based Groundwave Propagation Field Strength Prediction Simulator, IEEE Antennas and Propagation Magazine, vol. 49, no.5, Oct 2007, pp [15] G. Çakır, M. Çakır, L. Sevgi, A Novel Virtual FDTD-Based Microstrip Circuit Design and Analysis Tool, IEEE Antennas and Propagation Magazine, vol. 48, no.6, Dec 2006, pp [16] G. Cakır, M. Cakır, L. Sevgi, An FDTD-based Parallel Virtual Tool for the RCS Calculations of Complex Targets, IEEE Antennas and Propagation Magazine, vol. 56, no.5, Oct 2014, pp [17] L. Sevgi, A Mixed-Path Groundwave Field Strength Prediction Virtual Tool for Digital Radio Broadcast Systems in Medium and Short Wave Bands, IEEE Antennas and Propagation Magazine, vol. 48, no 4, Aug

27 Conclusions Engineers should be well equipped in terms of physical understanding, mathematical modeling as well as practical implementations. With this in mind, lectures of measurement techniques should be improved accordingly and concepts like accuracy, precision, resolution, error, uncertainty should be well taught. Within this context, Virtual tools have become attractive / effective tools in electromagnetic engineering education in addition to the techniques such as problem based learning, or, inquiry based teaching, etc. The aim of using virtual tools should be understanding the realworld and physics behind mathematical relations. 27