Innovative Antenna Design: Insights Through Modal Decomposition (EuCAP 2025)

19th European Conference on Antennas and Propagation, 2025, Stockholm, Sweden, March 30, 13:30 – 17:00, room: Maxwell (C2) 

Annotation

Electromagnetic wave phenomena, especially the guidance and radiation of electromagnetic waves, are commonly analyzed through modal representations, including normal and characteristic modes. This approach simplifies both analytical and numerical solutions, enabling effective analysis of complex engineering challenges. This course provides a comprehensive review of these techniques, covering traditional analytical methods and recent advances in numerical modeling. The instructors, with extensive careers dedicated to this field, will share their expertise, demonstrating a unified approach to modal decomposition techniques that facilitates practical problem-solving.

Learning objectives:

  • Classify modal techniques.
  • Understand relevant mathematical tools (eigenvalue problems, separation of variables, orthogonality, spectral theorem, Rayleigh quotient, numerical range).
  • Implement and apply the techniques for solving given problems.
  • Apply characteristic mode theory, including the link between impedance and scattering formulations or relation to spherical waves.
  • Understand similarities between scattering formulation of characteristic modes (Garbacz’s formulation) and impedance formulation (Harrington and Mautz), and how to unify them.
  • Use the properties of radiation modes to use them in practice.
  • Apply theoretical concepts to practical antenna design problems.

The course will offer a good balance between mathematics, EM theory, and code implementation. The participants will be provided with codes determining the bounds on the antenna metrics (gain, radiation efficiency, Q-factor) and performing topology optimization. A worksheet with analytical solutions will be distributed as well.

Instructors

Mats Gustafsson (Lund University, Sweden, EU)
Miloslav Capek (Czech Technical University, Czech Republic, EU)

Program (estimation :))

  • (13:30 – 13:50) Introduction
  • (13:50 – 14:15) Mathematical Background
  • (14:15 – 14:55) Normal Modes
  • (14:55 – 15:15) Characteristic Modes – Introduction
  • (15:15 – 15:35) Coffee Break
  • (15:35 – 16:20) Characteristic Modes – Scattering Formulation
  • (16:20 – 16:55) Diagonalization of Optimization Problems and Radiation Modes
  • (16:55 – 17:00) Conclusion

Materials

Lectures can be downloaded from THIS link with the password received on-site.
Cheat-sheet with integral-equation-based matrix operators is here.

References

  1. Feynman, R. P., Leighton, R. B., and Sands, M: The Feynman Lectures on Physics, Volume II. Addison-Wesley, 1964.
  2. Morse, P. M., and Feshbach, H: Methods of Theoretical Physics, Part I & II. McGraw-Hill, 1953.
  3. Harrington, R. F: Time-Harmonic Electromagnetic Fields. Wiley-IEEE Press, 2001.
  4. Stratton, J. A.: Electromagnetic Theory. Wiley-IEEE Press, 2007.
  5. Garbacz, R. J.: Modal expansions for resonance scattering phenomena, Proc. IEEE , Vol. 53, No. 8, p. 856-864, 1965.
  6. Harrington, R. F., Mautz, J. R.: Theory of Characteristic Modes for Conducting Bodies, IEEE Trans. Antennas Propag. , Vol. 19, No. 5, p. 622-628, 1971.
  7. Gustafsson, M., Jelinek, L., Schab, K., Capek, M.: Unified Theory of Characteristic Modes: Part I – Fundamentals, IEEE Trans. Antennas Propag. , Vol. 70, No. 12, p. 11801-11813, 2022.
  8. Gustaffson, M., Jelinek, L., Schab, K., Capek, M.: Unified Theory of Characteristic Modes: Part II – Tracking, Losses, and FEM Evaluation, IEEE Trans. Antennas Propag., Vol. 70, No. 13, pp. 11814-11824, 2022.
  9. Gustafsson, M., Jelinek, L., Capek, M., Lundgren, J., Schab, K.: Theory and Computation of Substructure Characteristic Modes, IEEE Trans. Antennas Propag., Vol. 73, No. 3, pp. 1321-1333, March 2025.
  10. Lundgren, J., Schab, K., Capek, M., Gustafsson, M., Jelinek, L.: Iterative Calculation of Characteristic Modes Using Arbitrary Full-wave Solvers, IEEE Antennas and Wireless Propagation Letters, Vol. 22, No. 4, pp. 799-803, 2023.
  11. Capek, M., Lundgren, J., Gustafsson, M., Schab, K., Jelinek, L.: Characteristic Mode Decomposition Using the Scattering Dyadic in Arbitrary Full-Wave Solvers, IEEE Trans. Antennas Propag., Vol. 71, No. 1, pp. 830-839, 2023.
  12. Lau, B. K., Capek M. and Hassan A. M.: Characteristic Modes: Progress, overview, and emerging topics, in IEEE Antennas and Propagation Magazine, vol. 64, no. 2, pp. 14-22, April 2022. (and the entire review series related to this paper)
  13. Sarkar T. K., Mokole E. L. and Salazar-Palma M.: An Expose on Internal Resonance, External Resonance, and Characteristic Modes, in IEEE Trans. Antennas Propag., vol. 64, no. 11, pp. 4695-4702, Nov. 2016,
  14. Gustafsson M.: Modes, Bounds, and Synthesis of Optimal Electromagnetic Scatterers, New J. Phys. 26 103039, 2024.
  15. Schab K., Chen, F. W., Jelinek L., Capek, M., Lundgren, J., Gustafsson, M.: Characteristic Modes of Frequency-Selective Surfaces and Metasurfaces from S-parameter Data, IEEE Trans. Antennas Propag, Vol. 71, No. 12, pp. 969-9706, Dec. 2023.
  16. Gustafsson, M., Tayli, D., Ehrenborg, C., Cismasu, M., Norbedo, S.: Antenna Current Optimization using MATLAB and CVX, FERMAT , Vol. 15, No. 5, p. 1-29, 2016.
  17. Jelinek, L., Capek, M.: Optimal Currents on Arbitrarily Shaped Surfaces, IEEE Trans. Antennas Propag., Vol. 65, No. 1, p. 329-341, 2017.
  18. Harrington, R. F.: Field Computation by Moment Methods, Wiley – IEEE Press, 1993.
  19. Capek, M., Jelinek, L.: Optimal Composition of Modal Currents For Minimal Quality Factor Q, IEEE Trans. Antennas Propag., Vol. 64, No. 12, pp. 5230-5242, 2016.
  20. Capek, M., Jelinek, L., Hazdra, P.: On the Functional Relation between Quality Factor and Fractional Bandwidth, IEEE Trans. Antennas Propag., Vol. 63, No. 6, pp. 2787-2790, 2015.
  21. Capek, M., Gustafsson, M., Schab, K.: Minimization of Antenna Quality Factor, IEEE Trans. Antennas Propag., Vol. 65, No. 8, pp. 4115-4123, 2017.
  22. Gustafsson, M., Capek, M., Schab, K.: Tradeoff Between Antenna Efficiency and Q-Factor, IEEE Trans. Antennas Propag., Vol. 67, No. 4, pp. 2482-2493, 2019.

Contacts: miloslav.capek[at]fel.cvut.cz (practical part) and mats.gustafsson[at]eit.lth.se (theoretical part). Please, add always the second lecturer into a copy as well.

Last edit: 2025-03-30 | 21:40:32 AM