State-space models and stored electromagnetic energy for antennas in dispersive and heterogeneous media

Research output: Book/ReportReport


Accurate and efficient evaluation of the stored energy is essential for Q-factors, physical bounds, and antenna current optimization. Here, it is shown that the stored energy can be estimated from quadratic forms based on a state-space representation derived from the electric and magnetic field integral equations. The derived expressions are valid for small antennas embedded in temporally dispersive and inhomogeneous media. The quadratic forms also provide simple single frequency formulas for the corresponding Q-factors. Numerical examples comparing the different Q-factors are presented for dipole and meander line antennas in conductive, Debye, and Lorentz media for homogeneous and inhomogeneous media. The computed Q-factors are also verified with the Q-factor obtained from the stored energy in Brune synthesized circuit models.


Research areas and keywords

Subject classification (UKÄ) – MANDATORY

  • Other Electrical Engineering, Electronic Engineering, Information Engineering
Original languageEnglish
PublisherElektro- och informationsteknik
Number of pages21
Publication statusPublished - 2017 Feb 9
Publication categoryResearch

Publication series

NameTechnical Report LUTEDX/(TEAT-7245)/1-21/(2017)

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Related research output

Mats Gustafsson & Casimir Ehrenborg, 2017 Nov 1, In : Radio Science. 52, 11, p. 1325-1343 19 p.

Research output: Contribution to journalArticle

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Related projects

Casimir Ehrenborg, Doruk Tayli, Marius Cismasu, Sven Nordebo, Daniel Sjöberg & Mats Gustafsson


Project: Research

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