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| 2. |
- Cismasu, Marius, et al.
(författare)
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Illustrations of Physical Bounds on Directive Antennas
- 2010
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Konferensbidrag (refereegranskat)abstract
- Applications of physical bounds for electromagnetic radiators can be used to derive a priori estimates for antenna parameters in terms of the directivity-bandwidth product. These estimates relate the static electric and magnetic polarizability of the radiating structure to its dynamic properties. The results have previously been illustrated for dipole radiators with good agreement. Here, the bounds are illustrated for some antennas with complex radiation patterns, i.e., directivity greater than 3/2 and narrow beams. The a priori estimates show good agreement with the realized antenna parameters.
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| 3. |
- Cismasu, Marius, et al.
(författare)
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Optimal Charges and Currents on Small Wire Antennas
- 2012
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Konferensbidrag (refereegranskat)abstract
- The optimum surface charge on a thin wire antenna is computed using a variational formulation in the low-frequency limit. This charge and its corresponding current are compared with simulation results for self resonant structures. The comparison shows that the currents and charges on self resonant structures resemble those in the static limit to a great extent.
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| 4. |
- Gustafsson, Mats, et al.
(författare)
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Absorption Efficiency and Physical Bounds on Antennas
- 2010
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Ingår i: International Journal of Antennas and Propagation. - Hindawi Publishing Corporation. - 1687-5869. ; 2010:Article ID 946746, s. 1-7
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Tidskriftsartikel (refereegranskat)abstract
- Abstract—The all spectrum absorption efficiency appears in the physical bounds on antennas expressed in the polarizability dyadics. Here, it is shown that this generalized absorption efficiency is close to 1/2 for small idealized dipole antennas and for antennas with a dominant resonance in their absorption. Also, the usefulness of this parameter is analyzed for estimation of antenna performance. The results are illustrated with numerical data for several antennas.
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| 5. |
- Gustafsson, Mats, et al.
(författare)
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Absorption efficiency and physical bounds on antennas
- 2010
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Rapport (övrigt vetenskapligt)abstract
- The all spectrum absorption efficiency appears in the physical bounds on antennas expressed in the polarizability dyadics. Here, it is shown that this generalized absorption efficiency is close to $1/2$ for small idealized dipole antennas and for antennas with a dominant resonance in their absorption. Also, the usefulness of this parameter is analyzed for estimation of antenna performance. The results are illustrated with numerical data for several antennas.
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| 6. |
- Gustafsson, Mats, et al.
(författare)
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Physical Bounds and Optimal Currents on Antennas
- 2011
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Rapport (övrigt vetenskapligt)abstract
- Physical bounds on the directivity Q-factor quotient and optimal current distributions are determined for antennas of arbitrary shape and size using an optimization formulation. A variational approach offers closed form solutions for small antennas expressed in the polarizability of the antenna structure. Finite sized antennas are solved using Lagrangian parameters in a method of moments formulation. It is also shown that the considered stored electric energy can be negative for electrically large objects. This effect is mitigated by a Helmholtz decomposition of the current density. Moreover, it is shown that the optimal charge density for a small antenna can be generated by several current densities. Numerical examples for small and large antennas are used to illustrate the results.
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| 7. |
- Gustafsson, Mats, et al.
(författare)
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Physical bounds and optimal currents on antennas
- 2012
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Ingår i: IEEE Transactions on Antennas and Propagatation. - 0018-926X. ; 60:6, s. 2672-2681
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Tidskriftsartikel (refereegranskat)abstract
- Physical bounds on the directivity Q-factor quotient and optimal current distributions are determined for antennas of arbitrary shape and size using an optimization formulation. A variational approach offers closed form solutions for small antennas expressed in the polarizability of the antenna structure. Finite sized antennas are solved using Lagrangian parameters in a method of moments formulation. It is also shown that the optimal charge density for a small antenna can be generated by several current densities. Numerical examples for small and large antennas are used to illustrate the results.
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| 8. |
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