Journal article
Reaching the Chu Lower Bound on Q With Magnetic Dipole Antennas Using a Magnetic-Coated PEC Core
We analytically solve the radiation problem for a spherical magnetic dipole antenna with a material-coated perfectly electrically conducting core. Using the closed-form expressions derived for the internal and external stored energies as well as for the radiation quality factor $Q$, we determine the optimal geometrical and material parameters of the antenna.
We show that the optimal permeability of the coating increases as the coating becomes thinner; as a result, the energy stored in it and the radiation quality factor $Q$ reduce. In the limit of an infinitely thin coating, the optimal permeability tends to infinity, the internal stored energy vanishes, and the $Q$ reaches the Chu lower bound, irrespective of the antenna electrical size $ka$ and permittivity of the coating.
Language: | English |
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Publisher: | IEEE |
Year: | 2011 |
Pages: | 2799-2805 |
ISSN: | 15582221 and 0018926x |
Types: | Journal article |
DOI: | 10.1109/TAP.2011.2158965 |
ORCIDs: | Kim, Oleksiy S. and Breinbjerg, Olav |
Chu lower bound Electrically small antennas Fundamental limitations Magnetic dipole Quality factor
Dipole antennas Magnetic cores Magnetic resonance Materials PEC core Permeability Permittivity Q factor Q-factor antenna radiation pattern antenna radiation patterns coatings dipole antennas electrical conductivity electrically small antennas energy storage fundamental limitations magnetic coating magnetic dipole magnetic dipole antennas magnetic moments magnetic permeability optimal permeability perfectly electrically conducting quality factor radiation quality factor