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Q factors for antennas in dispersive media

Gustafsson, Mats LU ; Tayli, Doruk LU and Cismasu, Marius LU (2014) In Technical Report LUTEDX/(TEAT-7232)/1-24/(2014) TEAT-7232.
Abstract
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.... (More)
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. (Less)
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author
organization
publishing date
type
Book/Report
publication status
published
subject
keywords
Antennas, Stored energy
in
Technical Report LUTEDX/(TEAT-7232)/1-24/(2014)
volume
TEAT-7232
pages
24 pages
publisher
[Publisher information missing]
project
EIT_CACO-EMD Complex analysis and convex optimization for EM design
language
English
LU publication?
yes
id
3f1a7d3d-da28-4770-81b9-8d2732225d0a (old id 4648444)
date added to LUP
2014-09-23 09:44:12
date last changed
2016-04-16 10:44:16
@techreport{3f1a7d3d-da28-4770-81b9-8d2732225d0a,
  abstract     = {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.},
  author       = {Gustafsson, Mats and Tayli, Doruk and Cismasu, Marius},
  institution  = {[Publisher information missing]},
  keyword      = {Antennas,Stored energy},
  language     = {eng},
  pages        = {24},
  series       = {Technical Report LUTEDX/(TEAT-7232)/1-24/(2014)},
  title        = {Q factors for antennas in dispersive media},
  volume       = {TEAT-7232},
  year         = {2014},
}