| 1. |
- Fhager, Andreas, 1976, et al.
(författare)
-
A statistical approach to gradient scaling microwave tomography
- 2007
-
Ingår i: Proceedings of EMB 07, computational electromagnetis, methods and applications, Lund, Sweden. ; , s. 153-160, s. 153-160, s. 153-160
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)
|
|
| 2. |
- Fhager, Andreas, 1976, et al.
(författare)
-
A Statistically Based Preconditioner for Two-Dimensional Microwave Tomography
- 2007
-
Ingår i: Proceedings of The Second International Workshop on Computational Advances in Multi-Sensor Adaptive Processing (CAMSAP2007), Dec. 12-14 2007, St. Thomas, U.S. Virgin Islands. - 9781424417148 ; , s. 173-176
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)
|
|
| 3. |
- Gustafsson, Mats, et al.
(författare)
-
Broadband self-complementary antenna arrays
- 2007
-
Ingår i: Ultra-wideband Short-pulse Electromagnetics: No. 8. - 9780387730455 ; , s. 17-24
-
Bokkapitel (övrigt vetenskapligt/konstnärligt)
|
|
| 4. |
- Gustafsson, Mats, et al.
(författare)
-
On the spectral efficiency of a sphere
- 2007
-
Ingår i: Progress in Electromagnetics Research-Pier. - 1070-4698. ; 67, s. 275-296
-
Tidskriftsartikel (refereegranskat)abstract
- In many cases it is desired to have both high capacity and small antennas in wireless communication systems. Unfortunately, the antenna performance deteriorate when the antennas get electrically small. In this paper fundamental limitations from antenna theory and broadband matching are used to analyze the spectral efficiency of an arbitrary antenna inserted inside a sphere.
|
|
| 5. |
- Gustafsson, Mats, et al.
(författare)
-
Physical limitations on antennas of arbitrary shape
- 2007
-
Ingår i: Royal Society of London. Proceedings A. Mathematical, Physical and Engineering Sciences. - : The Royal Society. - 1364-5021. ; 463:2086, s. 2589-2607
-
Tidskriftsartikel (refereegranskat)abstract
- In this paper, physical limitations on bandwidth, realized gain, Q-factor and directivity are derived for antennas of arbitrary shape. The product of bandwidth and realizable gain is shown to be bounded from above by the eigenvalues of the long-wavelength, high-contrast polarizability dyadics. These dyadics are proportional to the antenna volume and are easily determined for an arbitrary geometry. Ellipsoidal antenna volumes are analysed in detail, and numerical results for some generic geometries are presented. The theory is verified against the classical Chu limitations for spherical geometries and shown to yield sharper bounds for the ratio of the directivity and the Q-factor for non-spherical geometries.
|
|
| 6. |
- Gustafsson, Mats, et al.
(författare)
-
Physical limitations on D/Q for antennas
- 2007
-
Ingår i: ; , s. 1-3
-
Konferensbidrag (refereegranskat)abstract
- In this paper, physical limitations on the directivity D and Q-factor Q are derived for antennas of arbitrary shape. The quotient D/Q is shown to be bounded from above by the antenna volume and certain shape coefficients in terms of the eigenvalues of the high-contrast polarizability dyadic. The theory is exemplified by numerical results for the half-wave antenna with astonishing agreement.
|
|
| 7. |
- Gustafsson, Mats, et al.
(författare)
-
Physical limitations on scattering and absorption of antennas
- 2007
-
Ingår i: ; , s. 1-6
-
Konferensbidrag (refereegranskat)abstract
- In this paper, physical limitations are presented for antennas of arbitrary shape. Antenna properties such as bandwidth and directivity are shown to be bounded from above by the antenna volume and certain shape coefficients given by the eigenvalues of the high-contrast polarizability dyadic. The theoretical results are illustrated by a resonant loop antenna and an ultrawideband (UWB) spiral antenna.
|
|
| 8. |
- Gustafsson, Mats
(författare)
-
Surface integrated dipole arrays with tapered resistive edge sheets
- 2007
-
Ingår i: Journal Electromagnetic Waves and Applications. - : Informa UK Limited. - 1569-3937 .- 0920-5071. ; 21:6, s. 713-718
-
Tidskriftsartikel (refereegranskat)abstract
- The performance of antenna arrays can be severely degraded by edge diffraction and reflections of surface waves from the edges. Here, it is shown that tapered resistive sheets can reduce the edge diffraction for surface integrated dipole arrays. It is observed that the monostatic RCS and the oscillations in the induced voltages of the receiving antenna are reduced.
|
|
| 9. |
|
|
| 10. |
- Kristensson, Gerhard, et al.
(författare)
-
New physical limitations in scattering and antenna problems
- 2007
-
Ingår i: ; , s. 1-3
-
Konferensbidrag (refereegranskat)abstract
- The extinction cross section integrated over all frequencies is shown to be related to the electric and magnetic polarizability dyadics by exploiting the analytic properties of the forward scattering dyadic. This identity can be used threefold: 1) in scattering theory to bound the total scattering properties of an arbitrary scatterer, 2) in antenna theory to derive new physical limitations on antennas, and 3) in material modeling. The theory is illustrated by numerical simulations with excellent agreement.
|
|
