Q factors for antennas in dispersive media
Författare
Summary, in English
Stored energy and Q-factors are used to quantify the performance of small antennas. Accurate and efficient evaluation of the stored energy is also essential for current optimization and the associated physical bounds. Here, it is shown that the frequency derivative of the input impedance and the stored energy can be determined from the frequency derivative of the electric field integral equation. The expressions for the differentiated input impedance and stored energies differ by the use of a transpose and Hermitian transpose in the quadratic forms. The quadratic forms also provide simple single frequency formulas for the corresponding Q-factors. The expressions are further generalized to antennas integrated in temporally dispersive media. Numerical examples that compare the different Q-factors are presented for dipole and loop antennas in conductive, Debye, Lorentz, and Drude media. The computed Q-factors are also verified with the Q-factor obtained from the stored energy in Brune synthesized circuit models.
Publiceringsår
2014
Språk
Engelska
Publikation/Tidskrift/Serie
Technical Report LUTEDX/(TEAT-7232)/1-24/(2014)
Fulltext
- Available as PDF - 695 kB
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Dokumenttyp
Rapport
Förlag
[Publisher information missing]
Ämne
- Electrical Engineering, Electronic Engineering, Information Engineering
Nyckelord
- Antennas
- Stored energy
Status
Published
Projekt
- EIT_CACO-EMD Complex analysis and convex optimization for EM design
Report number
TEAT-7232
Forskningsgrupp
- Electromagnetic theory