CODEN:LUTEDX/(TEAT-3004)/1-20/(1992)

Annual Report 1991/92

Department ofElectromagnetic Theory

Department of Electromagnetic TheoryLund Institute of TechnologyP.O. Box 118S-221 00 Lund, SWEDEN

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Contents1 Introduction 1

2 Personnel and Budget 2

3 Research Activities 3

4 Dissertations and Published Papers 9

5 Guests and Seminars 11

6 Visits and Lectures by the Staff 14

7 Teaching Activities 17

8 Official Commissions 20

1 Introduction

The basis for the research and teaching activities at the Department of Electromag-netic Theory is the fundamental macroscopic electromagnetic laws as they apply tothe generation and propagation of electromagnetic effects in vacuum or in materialmedia. Special emphasis is also given to the theoretical study of the various devicesthat can be constructed to amplify and regulate these effects. In our ambition tomeet these goals all methods—analytic and numerical—are relevant to us.

The main research activities are concentrated to the area of electromagnetic scat-tering theory. Progress in this area is fundamental for the development of variousdevices and tools that use electromagnetic waves for information exchange. The lastfew decades have very clearly showed an increasing need for sensors and carriers ofinformation of this kind.

Several ways of classifying electromagnetic scattering problems can be proposed.The one that agrees with our aspirations is the division in direct and inverse scat-tering problems. In the direct scattering problem the geometry and the pertainingmaterial parameters are known and the scattered field is sought. The inverse scat-tering problem is the opposite–the goal is to infer information about the mediumthat produced the scattered field. Inverse scattering problems can be recognizedin many identification and measuring techniques. However, the correct interpreta-tion of these techniques can only be obtained from a comprehension of the basicand underlying features of the inverse scattering problem. Of primary interest inour research is the part of this problem that concerns the electromagnetic wavepropagation.

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2 Personnel and Budget

2.1 Personnel

Name Degree a Position b Part timeTommy Andersson TeknD DPeter Bernekorn CI D (920501–920630)Elzbieta Bohlin S 1/2Ingrid Brundell CI HA 1/2Per-Olof Brundell TeknD, Doc PGerhard Kristensson FD, Doc PRichard Lundin TeknD HLSten Rikte TeknL DBengt Stjernberg FI, PrefElzbieta Szybicka S 1/2Ingmar Tagesson TeknL HL

Ake Wisten CI HA (910701–910831)

Ingegerd Aberg CI D (910801–920630)

a CI Master of ScienceDoc DocentFD Doctor of Philosophy

TeknD Doctor of TechnologyTeknL Licentiate of Technology

b D Graduate StudentFI Research EngineerHA Lecturer

HL Senior LecturerP ProfessorPref Department Chairman

S Secretary

2.2 Funding

The total budget is summarized in the following table:

Source Amounta

From UHA 3500External research support 230

Total 3730

aAmounts in thousands of SEK.

The external research support is given by TFR (Swedish Research Council for En-gineering Sciences) under the auspices of TFR No. 241-91-849.Principal investigator: Gerhard Kristensson (together with Olle Brander, CTH, andStaffan Strom, KTH).Title of the project: “Inverse scattering: theory for generic problems, regularization,numerical and experimental implementations.”

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3 Research Activities

Our main research activities continue to be focused on the inverse scattering prob-lems. Together with Olle Brander, CTH, and Staffan Strom, KTH, we are work-ing on a joint project with the title “Inverse scattering: theory for generic prob-lems, regularization, numerical and experimental implementations.” This project isgiven substantial support by the Swedish Research Council for Engineering Sciences(TFR). The financial support of this project is also guaranteed under the next fiscalyear. Two new graduate students, Ingegerd Aberg and Peter Bernekorn, have alsojoined the department this year. We can therefore anticipate an extension of our re-search activities during the next years. Another important event was the dissertationof Tommy Andersson, who successfully defended his thesis “Electromagnetic scatter-ing by thin objects—Method of Moment calculations with singular basis functions.”Sten Rikte presented his Licentiate thesis “Propagation of transient electromagneticwaves in dispersive reciprocal bi-isotropic media,” in June.

Our international contacts have been very extensive during the year. Professor Ed-ward Jull, Department of Electrical Engineering, University of British Columbia,Vancouver, Canada, visited one week in March. During his visit he gave a very ap-preciated seminar series on the Geometrical Theory of Diffraction. This course wasfollowed not only by members from our department, but from other departments aswell. Vaughan Weston, Department of Mathematics, Purdue University, USA, vis-ited the department in May. He gave a seminar on the Green functions approach tosolve the three dimensional scattering problem in the time domain. Professor LassiPaivarinta, Department of Mathematics, Helsinki, Finland visited the departmentand lectured on his recent results concerning the uniqueness of the inverse electro-magnetic scattering problem. Professor Ismo Lindell, who was the faculty opponentof the dissertation of Tommy Andersson, presented his latest results on wave prop-agation in bi-isotropic media in a seminar. In June, Louis Fishman, Department ofMathematical and Computer Sciences, Colorado School of Mines, Golden, and DavidIsaacson and Margaret Cheney, Department of Mathematical Sciences, RensselaerPolytechnic Institute, Troy visited us. Professor Fishman presented new results onwave splitting in the frequency domain and Professors Isaacson and Cheney gavetwo introductory seminars to impedance tomography. Visits of this kind are veryimportant and vital for the development of the research activities at the department.

New contacts have been established during this past year with scientists in CIS.Specifically, Professor Youri Shestopalov from the Department of ComputationalMathematics and Cybernetics at Moscow State University, visited twice in thespring. He gave two seminars during his visits. This new contact is foreseen todevelop in the future.

The contacts with the Department of Electromagnetic Theory at the Royal Instituteof Technology, Stockholm, and the Institute of Theoretical Physics at ChalmersUniversity of Technology, Goteborg, have continued and these collaborations areborne out in several joint projects. Sailing He visited our department during one

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week in April and gave during that week two seminars. Jonas Friden from CTH hasbeen a regular visitor at our department during the whole year.

In September the series of workshops together with the Department of Electromag-netic Theory in Stockholm and the Institute of Theoretical Physics in Goteborgcontinued. The intention with these workshops is to promote joint projects and toexchange teaching experiences. The third workshop was organized by our depart-ment and was held in Rostanga in Skane. The format of the workshop this year wasa presentation of the research projects at the three departments.

The collaboration with the Applied Mathematical Sciences group at Ames Labora-tory, Iowa State University, USA under the leadership of Professor James Coroneshas also continued. We are also happy to collaborate with colleagues at the Depart-ment of Mathematics at the University of Akron, Ohio, USA, Department of Math-ematical Sciences at Rensselaer Polytechnic Institute, Troy, USA, Moore School ofElectrical Engineering at University of Pennsylvania, USA, Laboratory of Electro-magnetism and Department of Mathematics at University of Helsinki, Finland.

The main conference during the academic year was the ICIAM91 (InternationalConference on Industrial and Applied Mathematics) organized by SIAM in Wash-ington. Gerhard Kristensson and Staffan Strom, KTH, organized a mini-symposium“Time Domain Techniques for Inverse Scattering Problems.” Four invited speakerspresented their latest results on inverse scattering in the time domain.

The speakers were:

1. Professor Vaughan Weston, “Invariant Imbedding and Wave Splitting in 3D.”

2. Dr. David Wall, “Computational Aspects for Time Domain Inverse ScatteringAlgorithms.”

3. Dr. Anthon Tijhuis, “Time Domain Techniques in Electromagnetic InverseProfiling.”

4. Dr. Richard Albanese, “Electromagnetic Inverse Problems in Medical Science.”

Another important conference on inverse scattering problems was held in June inthe Finish Lapland.

The current research projects at the department can be summarized in the followingtable:

• Scattering by thin objects

• Theoretical investigations in the light of distribution theory and functionalanalysis

• Direct and inverse scattering problems in the time domain

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• Wave propagation in geophysics

• Mathematical modeling of dissipation and dispersion

• Minimization of dispersion in optical fibers

• Current distributions on conductors with edges

The subsections below give a short presentation of the current research projectslisted above and the main research activities at the department.

3.1 Scattering by thin objects

Researcher: Tommy Andersson

The method of moments (MoM) is an efficient and well established method forsolving electromagnetic scattering problems. The main computational efforts in theMoM show up as numerical integrations. The choice of appropriate basis functionsis also crucial for a fast convergence of the computations. This becomes criticalfor geometries with edges and corners. A canonical geometry in this context is aperfectly conducting, thin, flat object. Due to Babinet’s principle the solution isalso applicable to the case of an aperture in a perfectly conducting screen. Thepurpose of this project is to develop effective and accurate methods to simplify theintegrations involved in the MoM, as well as testing basis functions well adopted tothe particular singular behavior near the edges and corners. These concepts havesuccessfully been applied to the electrostatic and electrodynamic test cases. Themethods have also lately been implemented to more complicated and technicallyimportant structures—arrays of apertures in a thin conducting screen. Work is nowin progress to further enhance the efficiency of the method when applied to thesestructures.

3.2 Theoretical investigations in the light of distributiontheory and functional analysis

Researcher: Per-Olof Brundell

In a number of papers around 1900, Herman Weyl scrutinized some classical eigen-value-problems from mathematical physics. When analyzing the problem of elec-tromagnetic fields inside an opaque boundary (“Hohlraumstrahlung” as he labels it,“microwave cavity” in modern, technical language) he made, at first, a misjudge-ment, employing an inappropriate set of boundary conditions. This mistake wasremedied in a later paper (after it had been pointed out in a communication fromLevi-Civita). An attempt is made to clarify this situation in terms of the spectraltheorem of Hilbert space theory.

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3.3 Direct and inverse scattering problems in the time do-main

3.3.1 Transient wave propagation in bi-anisotropic media

Researcher: Gerhard Kristensson and Sten Rikte

In the electromagnetic community much attention is currently paid to the so calledbi-anisotropic and bi-isotropic media—sometimes referred to as magneto-electricmedia due to the coupling between the electric and magnetic fields in the consti-tutive relations. Another name, emphasizing different properties of the medium,is chiral media. Magnetic crystals that lack the symmetry of spatial inversion andthe symmetry of time inversion, are examples of materials that can show magneto-electric effects. The project was initiated by an investigation of the time dependentconstitutive relations in bi-anisotropic media. General physical assumptions andconsiderations imply that it is realistic to model the magneto-electric medium withdispersive constitutive relations. The main goal of this project is to solve the directand inverse scattering problems for a bi-isotropic medium with time domain tech-niques. The direct scattering problem has been solved for oblique incidence usingwave-splitting techniques. The imbedding equations for the scattering operators andthe Green functions equations are derived and some numerical computations thatillustrate the direct problem have been performed. These computations show thatno cross-polarized contribution to the reflected field appears at normal incidence inthe reciprocal case. Furthermore, it is shown that the wave front of the transmittedfield is rotated and explicit expressions of the angle of rotation is given both forhomogeneous and inhomogeneous media. The inverse scattering problem consists ofreconstructing at most four unknown susceptibility kernels as functions of time andthis problem will be addressed in a future work.

3.3.2 Transient wave propagation in anisotropic media

Researcher: Gerhard Kristensson

In a joint project with Jonas Friden from the Institute of Theoretical Physics, CTH,and Dr. Rodney Stewart, Applied Mathematical Sciences, Ames, USA, transientwave propagation in an anisotropic medium is investigated. The dispersive proper-ties of the medium are assumed to vary with depth. The medium is characterized bythe nine (six in the symmetric case) generalized susceptibility kernels. No explicitassumptions of the form of these kernels or of the type of anisotropy of the mediumare made. The aim of this project is to solve the direct and inverse scattering prob-lems for a medium of this kind. This is done with the wave splitting technique.The imbedding equations or the equations of the Green functions solve the directand inverse scattering problems. In this initial phase of the project the direct scat-tering problem has been in focus. Specifically, the general properties of the wave

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front in a general anisotropic media have been analyzed. Explicit expressions forthe propagation of the wave front have been found. These properties depend on thethe orientation of the optical axes of the medium and the degree of anisotropy. Theinverse scattering problem will be addressed in the near future.

3.3.3 Transient electromagnetic scattering in three-dimensional disper-sive media

Researcher: Gerhard Kristensson

This is a joint project together with colleagues from the Department of Electromag-netic Theory in Stockholm and the Department of Mathematics at the Universityof Akron, Ohio, USA. It concerns direct and inverse scattering of electromagneticwaves from a dispersive, homogeneous sphere. The method to solve this problemis based upon the wave splitting technique for a spherically symmetric region thatnow is available. The fact that the sphere is homogeneous simplifies the analysiscompared to the corresponding analysis of a non-dispersive inhomogeneous spherewhich was investigated in a previous project. The first part of this project concern-ing the direct scattering problem is completed and the inverse scattering problem isnow studied.

3.4 Wave propagation in geophysics

Researcher: Gerhard Kristensson

The joint project with Jonas Bjorkberg at the Department of Electromagnetic The-ory in Stockholm, aiming at developing efficient algorithms for geophysical pros-pecting, has continued. The objective is to fit the measured electromagnetic datain a bore hole to a specific mathematical model, that is appropriate for the situa-tion found in Northern Sweden. Some efficient methods for optimization are used tosolve this problem. More explicitly, optimization techniques based upon the Newtonmethod and Singular Value Decomposition (SVD) have been adopted. In order tostabilize the inversion to the effects of noise and imperfect data the SVD is trun-cated or filtered properly. Alternative stabilization using a penalty functional is alsoemployed. A preparatory work with reconstructions from noisy and clean syntheticdata has been completed. The project will continue by applying the method torealistic data, which are provided by Boliden Mineral AB.

3.5 Mathematical modeling of dissipation and dispersion

Researcher: Gerhard Kristensson

This project is a continuation of a previous work concerning the mathematical

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aspects of the constitutive relations. Under very general assumptions about themedium, it was proved that the constitutive relations are time convolution integralsof Riemann-Stieltjes type. This new project emphasizes the dissipative effects in themedium and the relations to the fixed frequency results are investigated. A usefulmathematical tool in this context is Bochner’s theorem, which relates a function ofpositive type to the Fourier transform of a bounded positive measure.

3.6 Minimization of dispersion in optical fibers

Researcher: Richard Lundin

Methods for the analysis of the guided modes in a cylindrical, radially inhomo-geneous dielectric waveguide, e.g. an optical fiber, have been developed. Thesemethods, developed for both the scalar and the vector cases, are based upon apower-series expansion technique and give high accuracy results at a comparativelylow cost in computer time. The objective of the current project is to design the ma-terial parameters in such a way that the chromatic dispersion is minimized. Morespecifically, to minimize the pulse broadening by tailoring the permittivity profile ofthe waveguide. An efficient method, based on Lagrange interpolation, for calculatingthe chromatic dispersion over a broad wavelength range has been developed. Therms-value of the chromatic dispersion over the wavelength range [1.25µm, 1.60µm]has been calculated and minimized for step-index fibers, triangular fibers, and a-power fibers.

3.7 Current distributions on conductors with edges

Researcher: Ingmar Tagesson

The main purpose of this project is to develop numerical solutions, which are ef-ficient and easy to program on a computer, to some integral equations relevant inelectromagnetic field theory. The singularities of the source distributions and of thekernels of the equations are dealt with in a careful way, and the remaining partis treated by direct integration according to the Euler-Maclaurin summation for-mula. This approach has been tested in two special cases where it has given veryencouraging results. The first case concerns the current distribution on a circulardisk induced by a plane wave propagating in the direction of the axis of the disk (orclose to it). The equivalent case of a circular aperture has been tested as well. Asa second case the current distribution on a straight cylindrical antenna of arbitrarythickness both as a receiver and as a transmitter has been investigated.

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4 Dissertations and Published Papers

4.1 Doctoral dissertations

Tommy Andersson, “Electromagnetic scattering by thin objects—Method of Mo-ment calculations with singular basis functions,” December 19, 1991.Faculty opponent: Professor Ismo Lindell, Electromagnetics Laboratory, HelsinkiUniversity of Technology, Espoo, Finland.

4.2 Licentiate dissertations

Sten Rikte, “Propagation of transient electromagnetic waves in dispersive reciprocalbi-isotropic media,” June 1, 1992.Reviewer: Docent Anders Karlsson, Department of Electromagnetic Theory, RoyalInstitute of Technology, Stockholm.

4.3 Journal publications

Tommy Andersson, “Method of moments and the use of multipole expansion,”J. Electro. Waves Applic., 5(11), 1237–1257 (1991).

Anders Karlsson and Gerhard Kristensson, “Constitutive relations, dissipation andreciprocity for the Maxwell equations in the time domain,” J. Electro. Waves Applic.,6(5/6), 537–551 (1992).

Tommy Andersson, “Moment-method calculations of scattering by a square plateusing singular basis functions and multipole expansions,”J. Electro. Waves Applic., (in press).

Richard Lundin, “Minimization of the chromatic dispersion over a broad wavelengthrange in a single-mode optical fiber,”Appl. Optics , (in press).

4.4 Contributions in books

Gerhard Kristensson, “Direct and inverse scattering problems in dispersive media—Green’s functions and invariant imbedding techniques,” in Direct and Inverse Boun-dary Value Problems ; Eds. R. Kleinman, R. Kress and E. Martensen, Methoden undVerfahren der Mathematischen Physik, Band 37, pp. 105–119 (1991).

Anders Bostrom, Gerhard Kristensson and Staffan Strom, “Transformation proper-ties of plane, spherical, and cylindrical scalar and vector wave functions—a review,”

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Chapter 4 in Handbook on Acoustic, Electromagnetic, and Elastic Wave Scatter-ing , Field Representation and Introduction to Scattering; Eds. V.V. Varadan, A.Lakhtakia and V.K. Varadan, Elsevier Science Publishers B.V., 165–210 (1991).

Anders Karlsson, Gerhard Kristensson and Henrik Otterheim, “Transient wavepropagation in gyrotropic media,” Invariant Imbedding and Inverse Problems , Eds.J.P. Corones, G. Kristensson, P. Nelson, and D.L. Seth, SIAM 1992.

Gerhard Kristensson and Robert J. Krueger, “Time domain inversion techniques forelectromagnetic scattering problems,” Invariant Imbedding and Inverse Problems ,Eds. J.P. Corones, G. Kristensson, P. Nelson, and D.L. Seth, SIAM 1992.

Anders Karlsson, Kevin Kreider and Gerhard Kristensson, “Wave splitting andimbedding equations for a spherically symmetric dispersive medium,” InvariantImbedding and Inverse Problems , Eds. J.P. Corones, G. Kristensson, P. Nelson,and D.L. Seth, SIAM 1992.

4.5 Dissertations

Tommy Andersson,“Electromagnetic scattering by thin objects—Method of Momentcalculations with singular basis functions,”LUTEDX/(TEAT-1004)/1-24/(1991).

Sten Rikte, “Propagation of transient electromagnetic waves in dispersive reciprocalbi-isotropic media,”LUTEDX/(TEAT-1005)/1-12/(1992).

4.6 Diploma Works

Hakan Andersson and Peder Malmlof, “Prob for matning av likstromsfalt,”LUTEDX/(TEAT-5010)/1-55/(1992).Advisor: Ingmar Tagesson.

Finn Persson, “Methods for Measurement of Magnetic Permeability and MagneticLosses on Toroidal and Cylindrical Samples,”LUTEDX/(TEAT-5011)/1-99/(1992).Advisor: Ingmar Tagesson (with AB Tetra Pak).

4.7 Technical reports

Gerhard Kristensson and Sten Rikte, “Scattering of transient electromagnetic wavesin bi-isotropic media,”LUTEDX/(TEAT-7015)/1-17/(1991).

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Vaughan H. Weston, “Time-domain Wave-Splitting of Maxwell’s Equations,”LUTEDX/(TEAT-7016)/1-25/(1991).

Tommy Andersson, “Moment-method calculations on multiple apertures using sin-gular basis functions,”LUTEDX/(TEAT-7017)/1-29/(1991).

Richard Lundin, “Minimization of the chromatic dispersion over a broad wavelengthrange in a single-mode optical fiber,”LUTEDX/(TEAT-7018)/1-16/(1992).

Gerhard Kristensson and Sten Rikte, “Transient wave propagation in reciprocal bi-isotropic media at oblique incidence,”LUTEDX/(TEAT-7019)/1-25/(1992).

Magnus Olsson, Sara Brockstedt, Richard Lundin and Bertil Persson, “Signal dis-placement and signal loss in MR imaging due to small metallic implants: a quanti-tative study using computer simulation,”Report from Department of Radiation Physics.

4.8 Teaching publications

Gerhard Kristensson, “Elektromagnetisk vagutbredning.” (New edition).

5 Guests and Seminars

5.1 Visitors at the department

Lassi Paivarinta, Department of Mathematics, University of Helsinki, August 26–28,1991.

Bertil Persson and Magnus Olsson, Department of Radiation Physics, Lund Univer-sity, November 19, 1991.

Herbert Uberall, Department of Physics, The Catholic University of America, Wash-ington, D.C., USA, December 5–6, 1991.

Ismo Lindell, Electromagnetics Laboratory, Helsinki University of Technology, Es-poo, Finland, December 18–20, 1991.

Staffan Strom, Department of Electromagnetic Theory, Royal Institute of Technol-ogy, Stockholm, December 18–20, 1991.

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Youri Shestopalov, Department of Computational Mathematics and Cybernetics,Moscow State University, February 3, 1992.

Edward Jull, Department of Electrical Engineering, University of British Columbia,Vancouver, Canada, March 22–28, 1992.

Sailing He, Department of Electromagnetic Theory, Royal Institute of Technology,Stockholm, April 6–14, 1992.

Youri Shestopalov, Department of Computational Mathematics and Cybernetics,Moscow State University, April 29–30, 1992.

Vaughan H. Weston, Department of Mathematics, Purdue University, May 18, 1992.

Louis Fishman, Department of Mathematical and Computer Sciences, ColoradoSchool of Mines, Golden, June 2–7, 1992.

David Isaacson, Department of Mathematical Sciences, Rensselaer Polytechnic In-stitute, Troy, June 7–12, 1992.

Margaret Cheney, Department of Mathematical Sciences, Rensselaer PolytechnicInstitute, Troy, June 17–12, 1992.

5.2 Seminars

Lassi Paivarinta, Department of Mathematics, University of Helsinki, “Uniquenesstheorems for electromagnetic problems,” August 27, 1991.

Ismo Lindell, Electromagnetics Laboratory, Helsinki University of Technology, Es-poo, Finland, “Wave propagation in and reflection from a layered bi-isotropic med-ium,” December 20, 1991.

Youri Shestopalov, Department of Computational Mathematics and Cybernetics,Moscow State University, “Applications of the methods of Green’s potentials forsome boundary eigenvalue problems for Helmholtz operator with spectral parametersin boundary conditions,” February 3, 1992.

Edward Jull, Department of Electrical Engineering, University of British Columbia,Vancouver, Canada,“Diffraction by conductors with sharp edges,” March 23, 1992.

Edward Jull, Department of Electrical Engineering, University of British Columbia,Vancouver, Canada,“Geometrical theory of diffraction (GTD) for edges (incl. uni-form theories),” March 24, 1992.

Edward Jull, Department of Electrical Engineering, University of British Columbia,Vancouver, Canada,“Applications of GTD to waveguide radiators and reflector an-tennas,” March 25, 1992.

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Edward Jull, Department of Electrical Engineering, University of British Columbia,Vancouver, Canada,“The complex source point method and its applications,” March26, 1992.

Edward Jull, Department of Electrical Engineering, University of British Columbia,Vancouver, Canada,“Pulse diffraction by edges on plane and curved surfaces,” March27, 1992.

Sailing He, Department of Electromagnetic Theory, KTH, “Time-harmonic GreenFunctions Technique and Wave Propagation in a Stratified Nonreciprocal ChiralSlab with Multiple Discontinuities,” April 10, 1992.

Sailing He, Department of Electromagnetic Theory, KTH, “The use of compactGreen functions in direct and inverse scattering for a stratified dissipative slab inthe time domain,” April 14, 1992.

Youri Shestopalov, Department of Computational Mathematics and Cybernetics,Moscow State University, “Some remarks on recent development in scattering theoryand related questions in the Russia and the Ukraine,” April 30, 1992.

Vaughan H. Weston, Department of Mathematics, Purdue University, “InvariantImbedding in 3-D: The Green’s Functions Approach to the Inverse Problem,” May18, 1992.

Sten Rikte, “Propagation of transient electromagnetic waves in dispersive reciprocalbi-isotropic media,” June 1, 1992.

Louis Fishman, Department of Mathematical and Computer Sciences, ColoradoSchool of Mines, Golden, “Wave Field Splitting, Invariant Imbedding and PhaseSpace Methods in Direct and Inverse Scattering,” June 3, 1992.

David Isaacson, Department of Mathematical Sciences, Rensselaer Polytechnic In-stitute, Troy, “Impedance Imaging and Eigenvalues,” June 9, 1992.

Margaret Cheney, Department of Mathematical Sciences, Rensselaer PolytechnicInstitute, Troy, “Impedance Imaging and Layer-Stripping,” June 10, 1992.

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6 Visits and Lectures by the Staff

6.1 Visits to other institutes and departments

Gerhard Kristensson:

Mathematics Department, Rensselaer Polytechnic Institute, Troy, USA, July6–7, 1991.

Moore School of Electrical Engineering, University of Pennsylvania, Philadel-phia, USA, July 13–16, 1991.

Department of Electromagnetic Theory, Royal Institute of Technology, Stock-holm, November 26–28, 1991.

Department of Electromagnetic Theory, Royal Institute of Technology, Stock-holm, February 28–30, 1992.

Statens Provningsanstalt, Boras, February 5, 1992.

Department of Electron Physics, Chalmers University of Technology, Gote-borg, February 5, 1992.

Spring meeting with the Swedish Physical Society (Svenska Fysikersamfundet),Mathematical Physics Section, Uppsala, May 20, 1992.

Department of Electromagnetic Theory, Royal Institute of Technology, Stock-holm, May 21, 1992.

Spring meeting with SNRV (National Committee of Radio Science, URSI),KVA, Stockholm, May 22, 1992.

6.2 Guest Lectures by the department’s staff

Gerhard Kristensson:

Department of Electrical Engineering, University of Pennsylvania, Philadel-phia, USA. Title of the talk: “Scattering of Electromagnetic Waves in Dissi-pative and Dispersive Media,” July 15, 1991.

6.3 Participation in conferences

Gerhard Kristensson:

Participated with an invited paper at the PIERS conference, MIT, Cambridge,MA, USA. Title of the talk: “Transient Scattering in Bi-isotropic Media,” (co-author: Sten Rikte), July 1–5, 1991.

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Chairman at the PIERS conference, MIT, Cambridge, MA, USA. Session:“Chiral Materials and Applications,” July 1–5, 1991.

Participated with an invited paper at the ICIAM91 conference, WashingtonD.C., USA. Title of the talk: “Inverse Scattering Problems of ElectromagneticWaves in Bi-Isotropic Media using Time Domain Techniques,” (co-author:Sten Rikte), July 8–12, 1991.

Chairman at the ICIAM91 conference in Washington D.C., USA. Session:“Time Domain Techniques for Inverse Scattering Problems,” July 8–12, 1991.

Organizer of a mini-symposium at ICIAM91 conference in Washington D.C.,USA. Session Program: “Time Domain Techniques for Inverse Scattering Prob-lems,” July 8–12, 1991 (together with Staffan Strom, KTH).

Participated with an invited paper at the XVII Convention on Radio ScienceURSI/IEEE, Abo, Finland. Title of the talk: “Scattering of transient electro-magnetic waves in bi-isotropic media,” (co-author: Sten Rikte), November 11,1991.

Chairman at the XVII Convention on Radio Science URSI/IEEE, Abo, Fin-land. Session: “Electromagnetic theory and chiral materials,” November 11,1991.

Participated with an invited paper at a conference on FEM, BEM and PDE forApplications and Industry, Linkoping. Title of the talk: “Wave splitting—Atool to solve PDE,” December 9–12, 1991.

Participated with an invited paper at The Lapland Conference on InverseProblems, Saariselka, Inari, Finland. Title of the talk: “Wave splitting andinverse scattering problems in the time domain,” June 14–20, 1992.

Chairman at The Lapland Conference on Inverse Problems, Saariselka, Inari,Finland, June 14–20, 1992.

Sten Rikte

Participated at the XVII Convention on Radio Science URSI/IEEE, Abo, Fin-land. Title of the talk: “Scattering of transient electromagnetic waves in bi-isotropic media,” November 11, 1991.

6.4 Other activities

Workshop together with colleagues from the Department of Electromagnetic The-ory, Royal Institute of Technology, Stockholm, and Institute of Theoretical Physics,CTH, Goteborg at Rostanga, September 5–6, 1991.

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Participants:Tommy Andersson Sten RikteGerhard Kristensson Elzbieta SzybickaRichard Lundin Ingmar Tagesson

Ingegerd Aberg

Contributed with an exhibition at the 30th anniversary of Engineering Physics,December 4–6, 1991.

Per-Olof Brundell: Sektionsseminarium E. Title of the talk: “Minnen fran min endaingenjorsanstallning. (Problem med motbocker, signaltransmission och digi-talteknik anno 1952). Mm,” May 8, 1992.

Gerhard Kristensson:

Chairman of the examining committee for Jonas Bjorkberg, Department ofElectromagnetic Theory, Royal Institute of Technology, Stockholm. Title ofthe thesis: “The Null-Field Approach to Elliptic Disks: Theory and Applica-tions to Electromagnetic Prospecting,” November 27, 1991.

Member of the examining committee for Sailing He, Department of Electro-magnetic Theory, Royal Institute of Technology, Stockholm. Title of the thesis:“Time Domain Direct and Inverse Scattering for Higher Dimensional FieldsPropagating in Dissipative Stratified Media,” January 29, 1992.

Member of the examining committee for Sven Nordholm, Signal ProcessingGroup, Lund Institute of Technology. Title of the thesis: “Broadband Adap-tive Beamforming with Applications in Acoustic Signal Processing,” February14, 1992.

Member of the examining committee for Magnus Olsson, Department of Radi-ation Physics, Lund University. Title of the thesis: “Magnetic Field Perturba-tion in Proton MR Imaging. A Study of a Contrast Agent and of Distortionsdue to Metallic Implants,” May 7, 1992.

6.5 Referee for international journals

Tommy Andersson:

Journal of Electromagnetic Waves and Applications .

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Gerhard Kristensson:

Journal of Electromagnetic Waves and Applications .

Radio Science.

Wave Motion.

7 Teaching Activities

During the past year Ake Wisten has moved to the university in Lulea and to asimilar teaching position there. We are very sorry to see Ake leave and wish himgood luck at his new position.

7.1 Undergraduate teaching

The following table gives an overview of the undergraduate courses that the depart-ment teaches.

ETE (Level) Name of the Course Lecturera

010 (E1) Elementary Circuit Theory Tommy Andersson020 (F1) Elementary Circuit Theory Tommy Andersson030 (D2) Elementary Circuit Theory Ingmar Tagesson040, 0189 (E2) Electromagnetic Field Theory Ingmar Tagesson

Tommy AnderssonSten Rikte

040, 0289 (E2) Electromagnetic Field Theory Richard LundinTommy AnderssonSten RikteIngmar Tagesson

Ingegerd Aberg050, 0189 (F2) Electromagnetic Field Theory Ingrid Brundell050, 0289 (F2) Electromagnetic Field Theory Ingrid Brundell060 (E3, F3) Electromagnetic Theory, Ingmar Tagesson

Advanced Course070 (E4, F4) Electromagnetic Wave Propagation Gerhard Kristensson

aThe examiner is given in bold face.

A brief presentation of the contents in the courses is provided by the following table.

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ETE 010 Elementary Circuit Theory (4 credit units, 56 hours):Lumped circuits and elements. Linear circuit elements (R, L, C, M). Sinusoidalsteady-state response. The concepts of phasor, impedance and admittance. Lineartransformers. Complex power and matching. The superposition theorem. TheThevenin and Norton equivalents. Reciprocity. Gain, input and output impedanceof a single transistor stage. Fourier series. Transients (brief outline).

ETE 020 Elementary Circuit Theory (4 credit units, 56 hours):Lumped circuits and elements. Linear circuit elements (R, L, C, M). Sinusoidalsteady-state response. The concepts of phasor, impedance and admittance. Lineartransformers. Complex power and matching. The superposition theorem. TheThevenin and Norton equivalents. Basic electronics. Gain, input and output imped-ance of a single transistor stage. Feedback. Operational amplifiers. Inverters,adders, integrators etc.

ETE 030 Elementary Circuit Theory (4 credit units, 56 hours):Lumped circuits and elements. Kirchhoff’s law. Linear circuit elements (R, L, C,M). The complex method. Linear transformers. Complex power and matching. Ba-sic network theorems. Linear time-invariant networks and Laplace transformation.Transmission lines. The general transmission-line equations. Waves with generaltime dependence on lossless lines. Reflection.

ETE 040 Electromagnetic Fields (9 credit units, 140 hours):Vector analysis: Scalar fields and vector fields. Gradient, divergence and curl inCartesian coordinates. Gauss’s theorem and Stokes’s theorem. Cylindrical coordi-nates. Spherical coordinates.Quasi-stationary fields: Coulomb’s law. Electrostatic fields in vacuum. Fields inthe presence of dielectrics. Electric images. Current fields. Biot-Savart’s law. Mag-netostatic fields in vacuum. Magnetic fields in material media. Magnetic circuits.General electromagnetic fields: The Maxwell equations. Plane waves. Retardedpotentials. Radiation fields from known sources and simple antennas. The Poyntingvector. Transmission lines.

ETE 050 Electromagnetic Fields (6 credit units, 98 hours):Quasi-stationary fields: Coulomb’s law. Electrostatic fields in vacuum. Fields inthe presence of dielectrics. Electric images. Current fields. Biot-Savart’s law. Mag-netostatic fields in vacuum. Magnetic fields in material media. Magnetic circuits.General electromagnetic fields: The Maxwell equations. Plane waves. Retardedpotentials. Radiation fields from known sources and simple antennas. The Poyntingvector. Transmission lines.

ETE 060 Electromagnetic Theory, Advanced Course (3 credit units, 56hours):This course is directed towards numerical computations within the following areas:Plane electrostatic fields. Scattering from a long conducting cylinder of arbitrarycross-section. Hollow waveguides. Coaxial cables with non-homogeneous insulation.Dielectric waveguides in the form of slabs and rods. Optical fibers.

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ETE 070 Electromagnetic Wave Propagation (3 credit units, 42 hours):Basic electromagnetic wave propagation is described in this course. The emphasis islaid on the propagation properties of plane harmonic waves in homogeneous media.Other topics treated in some detail are: dispersion, reflection transmission andscattering.

7.2 Diploma Works

Hakan Andersson and Peder Malmlof, “Prob for matning av likstromsfalt.”Advisor: Ingmar Tagesson.

Finn Persson, “Methods for Measurement of Magnetic Permeability and MagneticLosses on Toroidal and Cylindrical Samples.”Advisor: Ingmar Tagesson (with AB Tetra Pak).

7.3 Revisions of teaching materials

During the academic year the following major changes and revisions of the teachingmaterial have been made:

Gerhard Kristensson:

Revision of the course in Electromagnetic Wave Propagation (ETE 070). Ma-jor revision of the teaching material has been made. Title: “ElekromagnetiskVagutbredning.”

7.4 Graduate courses

Gerhard Kristensson:

ETE 070 Electromagnetic Wave Propagation, 1 credit units, 42 hours.

Ingmar Tagesson:

ETE 060 Electromagnetic Theory, Advanced Course, 3 credit units, 56 hours.

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8 Official Commissions

Gerhard Kristensson:

Member of the Swedish National Committee of URSI.

Deputy Chairman the Swedish Physics Society, Mathematical Physics Section.

Member of the School Committee of Electrical Engineering and ComputerSciences, Lund Institute of Technology.