Stored energies in electric and magnetic current densities for small antennas
Jonsson, Lars and Gustafsson, Mats LU
(2015)
In Royal Society of London. Proceedings A. Mathematical, Physical and Engineering Sciences
471(2176).
p.1-23
- Abstract
- Electric and magnetic currents are essential to describe electromagnetic-stored energy, and the associated antenna Q and the partial directivity to antenna Q-ratio, D/Q, for arbitrarily shaped structures. The upper bound of previous D/Q results for antennas modelled by electric currents is accurate enough to be predictive. This motivates us to develop the analysis required to determine upper and/or lower bounds for electromagnetic problems that include magnetic model currents. Here we derive new expressions for the stored energies, which are used to determine antenna Q bounds and D/Q bounds for the combination of electric and magnetic currents, in the limit of electrically small antennas. In this investigation, we show both new analytical... (More)
- Electric and magnetic currents are essential to describe electromagnetic-stored energy, and the associated antenna Q and the partial directivity to antenna Q-ratio, D/Q, for arbitrarily shaped structures. The upper bound of previous D/Q results for antennas modelled by electric currents is accurate enough to be predictive. This motivates us to develop the analysis required to determine upper and/or lower bounds for electromagnetic problems that include magnetic model currents. Here we derive new expressions for the stored energies, which are used to determine antenna Q bounds and D/Q bounds for the combination of electric and magnetic currents, in the limit of electrically small antennas. In this investigation, we show both new analytical results and we illustrate numerical realizations of them. We show that the lower bound of antenna Q is inversely proportional to the largest eigenvalue of certain combinations of the electric and magnetic polarizability tensors. These results are an extension of the electric only currents, which come as a special case. The proposed method to determine the minimum Q-value which is based on the new expressions for the stored energies, also yields a family of current-density minimizers for optimal electric and magnetic currents that can lend insight into antenna designs. (Less)
Please use this url to cite or link to this publication:
https://lup.lub.lu.se/record/5205005
- author
- Jonsson, Lars
and Gustafsson, Mats
LU
- organization
- publishing date
- 2015
- type
- Contribution to journal
- publication status
- published
- subject
- keywords
- stored energy, antennas, polarizability tensors, Q-factor, physical bounds
- in
- Royal Society of London. Proceedings A. Mathematical, Physical and Engineering Sciences
- volume
- 471
- issue
- 2176
- pages
- 1 - 23
- publisher
- Royal Society Publishing
- external identifiers
-
- scopus:84926303291
- ISSN
- 1364-5021
- DOI
- 10.1098/rspa.2014.0897
- project
- EIT_CACO-EMD Complex analysis and convex optimization for EM design
- language
- English
- LU publication?
- yes
- id
- f0be0a5e-07da-478a-8060-53d306f86b83 (old id 5205005)
- date added to LUP
- 2016-04-04 09:24:57
- date last changed
- 2022-02-21 00:37:26
@article{f0be0a5e-07da-478a-8060-53d306f86b83,
abstract = {{Electric and magnetic currents are essential to describe electromagnetic-stored energy, and the associated antenna Q and the partial directivity to antenna Q-ratio, D/Q, for arbitrarily shaped structures. The upper bound of previous D/Q results for antennas modelled by electric currents is accurate enough to be predictive. This motivates us to develop the analysis required to determine upper and/or lower bounds for electromagnetic problems that include magnetic model currents. Here we derive new expressions for the stored energies, which are used to determine antenna Q bounds and D/Q bounds for the combination of electric and magnetic currents, in the limit of electrically small antennas. In this investigation, we show both new analytical results and we illustrate numerical realizations of them. We show that the lower bound of antenna Q is inversely proportional to the largest eigenvalue of certain combinations of the electric and magnetic polarizability tensors. These results are an extension of the electric only currents, which come as a special case. The proposed method to determine the minimum Q-value which is based on the new expressions for the stored energies, also yields a family of current-density minimizers for optimal electric and magnetic currents that can lend insight into antenna designs.}},
author = {{Jonsson, Lars and Gustafsson, Mats}},
issn = {{1364-5021}},
keywords = {{stored energy; antennas; polarizability tensors; Q-factor; physical bounds}},
language = {{eng}},
number = {{2176}},
pages = {{1--23}},
publisher = {{Royal Society Publishing}},
series = {{Royal Society of London. Proceedings A. Mathematical, Physical and Engineering Sciences}},
title = {{Stored energies in electric and magnetic current densities for small antennas}},
url = {{http://dx.doi.org/10.1098/rspa.2014.0897}},
doi = {{10.1098/rspa.2014.0897}},
volume = {{471}},
year = {{2015}},
}