Active Learning for Optimization of EMC processes
With the ever increasing operating frequencies and powers, EMC has now become a major consideration on any project involving the design, construction, manufacture and installation of electrical and electronic equipment and systems. An important step in the design of components and prediction of EMC related problems is the modeling and simulation. The complexity and performance of electrical and electronic devices as well as the number and range of variables in the design spaces means that many of the Physics-Based (PB) used tools are either too slow or too inaccurate for effective design and optimization. Recently, machine learning (ML) tools and techniques have been increasingly used in the EMC domain either to improve PB approaches or to replace them. In ML, computers are used to probe vast amounts of data for structure. One requirement for the effective ML model building is the availability of these large datasets for the training and testing processes. The generation of simulation data of EMC systems using PB tools is more than often quite expensive and very time consuming.
The main goal of this project is the adaptation and extension of active learning schemes such as Bayesian Optimization (BO) to the realm of EMC. In active learning, the expensive to evaluate samples used for training and prediction are intelligently collected at each iteration to reduce the needed number of simulation runs. The active learning methods can be used for optimization tasks, modeling of systems or both at the same time. The main working points can be summarized as:
- Adaptation and foundation-laying of BO-based optimization and model building in the fields of EMC, SI, PI and bio-EMC.
- Establishment of a framework to evaluate the certainty in the solutions provided by the active learning scheme.
- Contribution to the available databases with the generated datasets for the service of the electrical engineering and EMC community.

Bayesian active learning and optimization scheme used to intelligently select the next samples to be simulated and added to the available data. The data is fed to the Bayesian model that predicts the optimal parameters while actively building an accurate model. Source: TET, TUHH

Animation of Bayesian active learning to approximate and maximize a 1D function f(x). The utility function is used at each iteration to pick the next best sample x to observe. The observations are used to create a more accurate approximation of the function and find the maxima. Source: TET, TUHH
Funding: Scholar of the Konrad Adenauer Foundation
Contact: Youcef Hassab
Start date: 02.11.2022
Analysis of Orbital Angular Momentum (OAM) antennas in Complex Environments
Electromagnetic waves can have a form of moment called the Orbital Angular Momentum (OAM). In waves with this property, the area perpendicular to the direction of propagation does not have a constant phase, as is the case with plane waves. Rather, the phase varies around the center of the wave and this phase distribution rotates in the direction of propagation. From the possible phase distributions and the direction of rotation different orthogonal modes result. This means that the modes do not influence each other and can therefore be used well for communication purposes.
In the past some properties of communication with OAM antennas have been investigated. The properties of OAM antennas shall now be further analyzed from the point of view of EMC.

Dipolar array of eight elements with which the first OAM mode is excited by operating the individual dipoles with a phase difference of ∆Φ=45°. The operating frequency is f=100 MHz. Source: TET, TUHH

Phase of the z-component of the E-field on the surface perpendicular to the direction of propagation. The phase was evaluated in three different distances to the antenna. As antenna a dipole array of eight elements was used, which excites the first OAM mode. The circular sections show how the phase rotates exactly 360° in the azimuthal direction. You can also see how this phase distribution rotates in the direction of propagation. Source: TET, TUHH
Funding: DFG
Contact: Michael Wulff, M Sc.
Start date: 01.12.2020
EMC of Complex Systems
Ph. D. Thesis Fabian Happ. 01.04.2012 – 01.09.2017
In this thesis a numerical method based on the Method of Moments and analytical formulations are developed to calculate electromagnetic fields in the vicinity of Carbon Fiber Composite (CFC) materials. The methods are applied to predict the shielding effectiveness of different CFC materials, to calculate lightning transfer functions for the coupling into an aircraft geometry made of CFC, and to estimate the influence of CFC on the crosstalk between transmission lines.

Apertures in a Computer casing (Source: TET, TUHH).

Current distribution on a field illuminated Computer casing (Source: TET, TUHH).
Related Publications:
An efficient implementation of the periodic method of moments for shielding effectiveness calculations of thin-wire grids Proceedings Article In: URSI AT-RASC, Gran Canaria, Spain, May 28 – June 1, 2018. |
Application of Huygens‘ Principle for the Fast Calculation of Field Penetration Through Aperture Arrays Journal Article In: IEEE Transactions on Electromagnetic Compatibility, vol. 6, pp. 2025-2028, 2018. |
Method of Moment Analysis of Layered Carbon Fiber Composites with Applications to Electromagnetic Compatibility PhD Thesis 2017, ISBN: 978-38440-5630-3. |
Numerical Shielding Analysis of Anisotropic Multilayer Materials by the Method of Moments Journal Article In: IEEE Transactions on Electromagnetic Compatibility, vol. 1, 2017. |
Crosstalk between wire pairs above a composite ground plane Proceedings Article In: 2016 International Symposium on Electromagnetic Compatibility - EMC EUROPE Wroclaw, Poland, 2016. |
On the Choice of Huygens’ Surfaces in the Vicinity of Electrically Small Apertures Proceedings Article In: EMC Europe, Wroclaw, Poland, September 5 – 9, 2016. |
Numerical Computation of Lightning Transfer Functions for Layered, Anisotropically Conducting Shielding Structures by the Method of Moments Journal Article In: Advances in Radio Science, 2016. |
An Extension of Schelkunoff’s Shielding Theory to Anisotropic Conducting Multilayer Materials Proceedings Article In: 2015 IEEE International Symposium on Electromagnetic Compatibility (EMC), Dresden, Germany, August 16-22, 2015. |
Benchmark Calculations of Magnetic Shielding at Low Frequencies Proceedings Article In: IEEE International Symposium on Electromagnetic Compatibility, EMC Europe, Gothenburg, Sweden,September 1-4, 2014. |
Numerische Simulation der Schirmwirkung von mehrlagigen, anisotrop leitfähigen Materialien Proceedings Article In: Internationale Fachmesse und Kongress für Elektromagnetische Verträglichkeit (EMV Düsseldorf), Düsseldorf, Germany, March 11-13, 2014. |
Methoden der Netzwerkmodellierung von Transferfunktionen indirekter Blitzeffekte auf Grundlage numerischer Simulation in Zeit- und Frequenzbereich Proceedings Article In: Internationale Fachmesse und Kongress für Elektromagnetische Verträglichkeit (EMV Düsseldorf) , Düsseldorf, Germany, March 11-13, 2014. |
Adaptive Macromodelling of Lightning Transfer Funcion from Numerical Calculations in Time and Frequency Domain Proceedings Article In: International Conference on Electromagnetics in Advanced Applications Torino, Italy, September 9-13, 2013. |
A Method for the Calculation of Electromagnetic Fields in the Presence of Thin Anisotropic Conductive Layers using the Method of Moments Proceedings Article In: EMC Europe 2013, Brugge, Belgium, September 2-6, 2013. |
Complete Modeling of Large Via Constellations in Multilayer Printed Circuit Boards Journal Article In: IEEE Transactions on Components, Packaging and Manufacturing Technology, vol. 3, no. 3, 2013. |
HIRF Protection Using Energy Selective Diode Arrays
Cheng Yang, M. Sc., (China Scholarship Council (CSC)), 01.04.2015 – 17.10.2016
With more and more electromagnetic energy being transmitted by radar, radio, TV, mobile, hotspot (Wi-Fi), satellite, and other transmitters, detrimental effects of electromagnetic waves on the environment, e.g. disturbance or even damage of electronic equipment, become more and more a concern. To ensure safe operation of various electronic systems in transmitting or receiving states, electromagnetic protection should be considered especially against high intensity radiation fields (HIRFs). This project focuses on diode arrays for implementation of self-activated and energy selective blocking of electromagnetic wave.
Based on the nonlinear behavior of diodes, diode arrays can be shown to be transparent with respect to small field amplitudes and opaque to large field amplitudes. In theory, we expect the structure to work like a spatial switch, while in practice its protection performance is limited by several factors, such as the response time and operating frequency range of the diodes, the transmission loss of the protective structure and near field coupling effects. Therefore, accurate full wave simulation are being used for evaluation of the electromagnetic performance of protective diode arrays. Up to now, mostly infinitely periodic diode arrays have been studied. Next steps include the simulation of finite and non-periodic diode arrays using the electromagnetic field simulator CONCEPT-II.

Geometrical model of diode array designed for vertical polarized protection against HIRF. The diode array consists of conductive strips and miniature diodes on a low dielectric loss substrate of thickness 0.8mm. The horizontal and vertical distance of adjacent diodes is 3.5 mm and 2.25, respectively (figure adapted from “A Novel Method of Energy Selective Surface for Adaptive HPM/EMP Protection,” IEEE APWL, vol. 12, pp. 112–115, 2013.)

Evaluation model of diode array in CONCEPT-II. The array was placed in the front window of a PEC box, and a receiving antenna is positioned inside the PEC box (side length approx. 50 cm). What can be seen are the surface currents on the PEC box (red color indicates high current amplitudes).
Related Publications:
Design Aspects for HIRF Protection of a Rectangular Metallic Cavity Using Energy Selective Diode Grids Proceedings Article In: IEEE Asia-Pacific International Symposium on Electromagnetic Compatibility (APEMC), Shenzhen, China, May 18-21, 2016. |
Impulse Response Optimization of Band-Limited Frequency Data for Hybrid Field-Circuit Simulation of Large-Scale Energy-Selective Diode Grids Journal Article In: IEEE Transaction on Electromagnetic Compatibility, vol. 58, no. 4, 2016. |
Validation of a Flexible Causality Treatment for Transient Analysis of Nonlinearly Loaded Structures Proceedings Article In: 2015 IEEE International Symposium on Electromagnetic Compatibility (EMC), Dresden, Germany, August 16-22, 2015. |
Analysis of Electromagnetic Interference in Server Casings
Ph.D. Thesis Alexander Vogt. 01.04.2011 – 08.04.2016
With increasing data rates EM emission has become a major issue for EMC and EMI considerations in current server designs. Major sources of EM emission inside include ICs, cables and connectors, and Printed Circuit Boards. While efficient techniques exist to model the interior coupling of PCB cavities (Zpp ), the external (3D) coupling still has to be computed using full-wave techniques.
This project aims to combine the different methods to model and simulate the components of the server. The dimensions and high data rates in addition to the high complexity of the individual components encountered in modern servers lead to a number of unknowns that are commonly in the range of several million. Therefore, efficient numerical methods and approximate models have to be developed.
Related Publications:
Modeling challenging EMC problems Journal Article In: IEEE Electromagnetic Compatibility Magazine, vol. 6, no. 3, pp. 45-54, 2017. |
Analysis of Electromagnetic Interference in Server Casings PhD Thesis 2016, ISBN: 978-3-8440-4660-1. |
On the Treatment of Arbitrary Boundary Conditions Using a Fast Direct H-Matrix Solver in MoM Journal Article In: IEEE Transactions on Antennas and Propagation, vol. 64, no. 8, 2016. |
Auswirkung absorbierender Materialien auf die Verkopplung von Komponenten innerhalb eines PC-Gehäuses Proceedings Article In: Internationale Fachmesse und Kongress für Elektromagnetische Verträglichkeit (EMV Düsseldorf) Düsseldorf, Germany, February 23-25, 2016. |
A Measurement Setup for Quantification of Electromagnetic Interference in Metallic Casings Journal Article In: IEEE Transactions on Electromagnetic Compatibility, vol. 57, no. 6, 2015. |
Modeling of Mutual Coupling between Coaxial Probes in Flat Metallic Casings Using the Contour Integral Method Proceedings Article In: 2015 International Conference on Electromagnetics in Advanced Applications (ICEAA), Turin, Italy, September 07-11, 2015. |
Numerical and Experimental Evaluation of Electromagnetic Coupling between Radiating Antenna Structures inside a Computer Casing Proceedings Article In: 2015 IEEE International Symposium on Electromagnetic Compatibility (EMC) Dresden, Germany, August 16-22, 2015. |
Solving highly resonant structures using a fast direct H-matrix solver in the method of moments Workshop IEEE EMC International Symposium on Electromagnetic Compatibility, Dresden, Germany, August , 2015. |
Modeling using MoM – Solving challenging realworld problems Workshop IEEE EMC International Symposium on Electromagnetic Compatibility, Gothenburg, Sweden, September, 2014. |
Einfluss von absorbierenden Materialien auf die elektromagnetische Strahlung von Leiterplatten Proceedings Article In: Internationale Fachmesse und Kongress für Elektromagnetische Verträglichkeit (EMV Düsseldorf) , Düsseldorf, Germany, March 11-13, 2014. |
Modeling Absorbing Materials in Cavities with Apertures Using the Thin Sheet Approximation Proceedings Article In: Asia-Pacific EMC Symposium (APEMC), Melbourne, Australia, May 20-23, 2013. |
Progress Towards a Combined CIM/MoM Approach for EMI Analysis of Electronic Systems Proceedings Article In: IEEE EMC Europe Symposium, Rome, Italy, September 17-21, 2012. |
Applicability of the Thin Sheet Approximation to the Analysis of EM Emission from Coated PCBs Proceedings Article In: IEEE EMC International Symposium on Electromagnetic Compatibility, Pittsburgh, USA, August 5-10, 2012. |
Application of the Characteristic Mode Analysis to Antenna Design and Electromagnetic Compatibility
Alexander-von-Humboldt Fellowship Prof. Qi Wu. 01.03.2014 – 29.02.2016
The Characteristic Mode Analysis (CMA) – based on the fundamental works of Harrington and Mautz – is a well-known numerical tool for antenna analysis and design. Within the numerical framework of the method of moments (MoM) the characteristic modes are found by the solution of a weighted matrix eigenvalue equation formulated with the MoM system matrix. The resulting current distributions are the eigencurrents and eigenvalues, respectively. The eigenvalues indicate if the corresponding eigencurrents may store primarily magnetic energy, or electric energy, or if they are “at resonance” and may radiate efficiently if excited. The eigencurrents constitute a set of (orthogonal) modes characteristic to the investigated structure (hence the name) and independent of any excitation. In antenna design inspection of the eigencurrents allows to identify e.g. suitable locations for generators and ways to improve radiation efficiency. In EMC analysis, the goals are opposite: analyze a potentially radiating structure and reduce its potential for emission.
During the Alexander von Humboldt Fellowship of Prof. Qi Wu at TUHH CMA was applied successfully to antenna design and extended to EMC analysis of digital systems. A full report of his fellowship is given in the following document PDF.

Eigencurrents in A/m and radiation eigenpatterns of a cubic heatsink on a motherboard at 500 MHz obtained by CONCEPT-II. Image taken from: “Characteristic Mode Analysis of Radiating Structures in Digital Systems,” IEEE Electromagnetic Compatibility Magazine.
Related Publications:
Characteristic Mode Analysis of Radiating Structures in Digital Systems Journal Article In: IEEE Electromagnetic Compatibility Magazine , vol. 5, no. 4, 2016. |
Evaluation of isolation between blade antennas in pre-design phase using a synthesized model Proceedings Article In: IEEE Asia-Pacific International Symposium on Electromagnetic Compatibility (APEMC), Shenzhen, China, May 18-21, 2016. |
A Measurement Setup for Quantification of Electromagnetic Interference in Metallic Casings Journal Article In: IEEE Transactions on Electromagnetic Compatibility, vol. 57, no. 6, 2015. |
Modeling of Mutual Coupling between Coaxial Probes in Flat Metallic Casings Using the Contour Integral Method Proceedings Article In: 2015 International Conference on Electromagnetics in Advanced Applications (ICEAA), Turin, Italy, September 07-11, 2015. |
Numerical and Experimental Evaluation of Electromagnetic Coupling between Radiating Antenna Structures inside a Computer Casing Proceedings Article In: 2015 IEEE International Symposium on Electromagnetic Compatibility (EMC) Dresden, Germany, August 16-22, 2015. |
Rigorous Eigenmode Analysis of Conducting Sphere Proceedings Article In: 2015 9th European Conference on Antennas and Propagation (EuCAP), Lisabon, Portugal, April 12-17 , 2015. |
A Broadband Dipole Antenna for Multi-Service Indoor Distributed Antenna System (MS-IDAS) Journal Article In: IEEE Antennas and Wireless Propagation Letters, vol. 14, 2015. |
Theoretic and Experimental Analysis of a Reflector-backed Dipole Antenna for 1-3 GHz EMC Test Proceedings Article In: IEEE International Symposium on Electromagnetic Compatibility, EMC Europe, Gothenburg, Sweden, September 1-4, 2014. |
On the Eigenmodes of Small Conducting Objects Journal Article In: IEEE Antennas and Wireless Propagation Letters, vol. 13, 2014. |
Accurate and Efficient Algorithms in the Method of Moments for the Analysis of High Intensity Radiated Field Coupling into Aircraft
Ph. D. Thesis Arne Schröder. 01.09.2009 – 31.08.2013

Bistatic radar cross section (RCS) of aircraft to the left. The comparison of two diffrent computation methods shows good agreement. (Source: TET, TUHH). (Source: TET, TUHH).
Related Publications:
Numerical Shielding Analysis of Anisotropic Multilayer Materials by the Method of Moments Journal Article In: IEEE Transactions on Electromagnetic Compatibility, vol. 1, 2017. |
Accurate and Efficient Algorithms in the Method of Moments for the Analysis of High Intensity Radiated Field Coupling into Aircraft PhD Thesis 2014, ISBN: 978-3-8440-2899-7. |
Fast Evaluation of Electromagnatic Fields using a Parallelized Adaptive Cross Approximation Journal Article In: IEEE Transactions on Antennas and Propagation, vol. 62, no. 5, 2014. |
Effiziente Simulation der Einkopplung statistischer Felder in Leitungsstrukturen mit der Momentenmethode Proceedings Article In: Internationale Fachmesse und Kongress für Elektromagnetische Verträglichkeit (EMV Düsseldorf) , Düsseldorf, Germany, March 11-13, 2014. |
Analysis of High Intensity Radiated Field Coupling into Aircraft using the Method of Moments Journal Article In: IEEE Transactions on Electromagnetic Compatibility, vol. 56, no. 1, 2014. |
A Method for the Calculation of Electromagnetic Fields in the Presence of Thin Anisotropic Conductive Layers using the Method of Moments Proceedings Article In: EMC Europe 2013, Brugge, Belgium, September 2-6, 2013. |
A Hybrid Approach for Rapid Computation of Two-Dimensional Monostatic Radar Cross Section Problems With the Multilevel Fast Multipole Algorithm Journal Article In: IEEE Transactions on Antennas and Propagation, vol. 60, no. 12, 2012. |
HIRF Interaction with Metallic Aircrafts. A Comparison Between TD and FD Methods Proceedings Article In: International Symposium on Electromagnetic Compatibility (EMC Europe), Rome, Italy, September 17-21, 2012. |
Efficient Compression of Far Field Matrices in Multipole Algorithms based on Spherical Harmonics and Radiating Modes Journal Article In: Advanced Electromagnetics Symposium (AES), Paris, France , April 16-19 and Advanced Electromagnetics, vol. 1, no. 2, 2012. |
Beschleunigung schneller Löser in der Momentenmethode bei Einkopplungsproblemen mit Mehrfachanregung Proceedings Article In: Internationale Fachmesse und Kongress für Elektromagnetische Verträglichkeit (EMV Düsseldorf) , Düsseldorf, Germany, February 7-9, 2012. |
Numerical and Experimental Investigations on a Metallic Fuselage Model with Apertures Proceedings Article In: EMC Europe Conference, York, United Kingdom, September 26-30, 2011. |
Investigation of Field Coupling into a Carbon Fiber Aircraft Model with the Method of Moments Proceedings Article In: International Conference on Electromagnetics in Advanced Applications (ICEAA), Torino, Italy, September 12-16, 2011. |
Exploiting Planes of Magnetic Symmetry in the Fast Multipole Method Proceedings Article In: International Symposium on EMC Europe, Wroclaw, Poland, September 13-17, 2010. |
Ausnutzung magnetischer Symmetrie bei der numerischen Analyse von Feldproblemen mit der schnellen Multipolmethode Proceedings Article In: Internationale Fachmesse und Kongress für Elektromagnetische Verträglichkeit (EMV Düsseldorf) , Düsseldorf, Germany, March 9-11, 2010. |
Development of a Full-Wave Module for the High Intensity Radiated Field (HIRF) Synthetic Environment
EU-Project. 01.12.2008 – 13.05.2013
The “HIRF Synthetic Environment”, financed by the EU with a total of 45 partners, research project had the goal to provide a numerical modelling framework to the aeronautic industry which can be used during the development phase of aircraft for prediction of adequate electromagnetic immunity. For this purpose several state-of-the-art computational electromagnetic codes were integrated into a common modeling platform and validated against each other and against measurements. From the part of the Institute of Electromagnetic Theory the MoM code CONCEPT-II could be successfully adapated and integrated into the synthetic environment.
In the future, the availability of such a HIRF Synthetic Environment framework becomes more and more significant in order to be able to cope with competing requirements of new designs, with the related increase of testing, and the general demand of costs and time reductions.
Surface current distribution on aircraft due to HIRF illumination calculated by CONCEPT-II (Source: TET, TUHH).
Further Information: http://cordis.europa.eu/project/rcn/89387_en.html