| 1. |
- Derneryd, Anders, et al.
(författare)
-
Mobile and terminal antennas
- 2003
-
Ingår i: Antenn 03. Nordic Antenna Symposium. Conference Proceedings. ; , s. 37-38
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- This project deals with the analysis of antennas for mobiles and terminals in the form of a patch element on a grounded substrate. A special case of this antenna element is the PIFA-element. The analysis is based on the propagator method, a vector generalisation of the transmission line theory, that has been extended to the analysis of surface waves in inhomogeneous permittivity profiles. Analyses of combined antenna radiation pattern and propagation channel characteristics have been initiated in order to demonstrate the performance advantage of exploiting two-antenna signals on a terminal for diversity or interference suppression. A generic two-antenna terminal is presented in this paper which improves capacity on reception. Signal correlation coefficients that depend on the mutual coupling are calculated.
|
|
| 2. |
- Engström, Christian, et al.
(författare)
-
Homogenization of the Maxwell equations using Floquet-Bloch decomposition
- 2003
-
Ingår i: Mathematical and numerical waves 2003. - Berlin, Heidelberg : Springer. - 9783642558566 - 354040127X ; , s. 412-416
-
Konferensbidrag (refereegranskat)abstract
- Using Bloch waves to represent the full solution of the Maxwell equations inperiodic media, we study the limit process where the material's period becomes much smaller than the wavelenght. it is seen that effective material parameters can be extracted and explicity represented in terms of the non-vanishing Bloch waves, providing an alternative means of homogenization.
|
|
| 3. |
|
|
| 4. |
- Kristensson, Gerhard, et al.
(författare)
-
Exotic materials in radome and antenna design
- 2003
-
Ingår i: Antenn 03. Nordic Antenna Symposium. Conference Proceedings. ; , s. 55-56
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The purpose of this paper is to investigate the potential of complex or exotic materials in radome and antenna design. The existing analysis methods need to be extended to cope with these materials in generic radome and antenna geometries. This paper focuses on electromagnetic properties of the material, the means of realizations, and the methods of computations. The main objectives of this paper are: 1) to extend the established tools of analysis in radome technology, e.g. to correctly model the effects of background material of an FSS. 2) To model complex materials used in antenna technology. 3) The effect on the radiation properties on randomly located antennas or passive elements. The new ways to calculate the effective electric and magnetic material parameters is also developed
|
|
| 5. |
- Kristensson, Gerhard
(författare)
-
Homogenization of spherical inclusions
- 2003
-
Ingår i: Progress in Electromagnetics Research-Pier. - 1070-4698. ; PIER 42, s. 1-25
-
Tidskriftsartikel (refereegranskat)abstract
- The homogenization of cubically arranged, homogeneous spherical inclusions in a background material is addressed. This is accomplished by the solution of a local problem in the unit cell. An exact series representation of the effective relative permittivity of the heterogeneous material is derived, and the functional behavior for small radii of the spheres is given. The solution is utilizing the translation properties of the solutions to the Laplace equation in spherical coordinates. A comparison with the classical mixture formulas, e.g., the Maxwell Garnett formula, the Bruggeman formula, and the Rayleigh formula, shows that all classical mixture formulas are correct to the first (dipole) order, and, moreover, that the Maxwell Garnett formula predicts several higher order terms correctly. The solution is in agreement with the Hashin-Shtrikman limits.
|
|
| 6. |
- Kristensson, Gerhard
(författare)
-
Homogenization of the Maxwell equations in an anisotropic material
- 2003
-
Ingår i: Radio Science. - 0048-6604. ; 38:2, s. 1-19
-
Tidskriftsartikel (refereegranskat)abstract
- This paper contains an overview of the homogenization of anisotropic materials at fixed frequency using the concept of two-scaled convergence. The homogenized electric and magnetic parameters, the relative permittivity, and the relative permeability are found by suitable averages of the solution of a local problem in the unit cell. A comparison between the exact homogenization method presented in this paper and the traditional mixture formulae, which are based on physical arguments, is made.
|
|
| 7. |
- Kristensson, Gerhard
(författare)
-
On the generation of surface waves in frequency selective structures
- 2003
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- In this paper, we discuss and analyze the criteria for the existence and the generation of surface modes in dielectric slabs with and without metallic layers (frequency selective structures, FSS). The material parameter of the slab is in general bianisotropic, but the examples and the numerical computations show only isotropic materials. It is shown that there are three different categories of resonances occurring in power transmission and power reflection in a FSS, i.e., 1) resonances in the array, 2) surface wave excitations, and 3) onset of grating lobes.
|
|
| 8. |
- Kristensson, Gerhard, et al.
(författare)
-
Radiation efficiency and surface waves for patch antennas on inhomogeneous substrates
- 2003
-
Ingår i: IEE Proceedings - Microwaves Antennas and Propagation. - : Institution of Engineering and Technology (IET). - 1350-2417. ; 150:6, s. 477-483
-
Tidskriftsartikel (refereegranskat)abstract
- Surface wave characteristics and radiation efficiency are calculated for a patch antenna with a given current distribution and located on top of an inhomogeneous, isotropic substrate. The substrate is infinite in the lateral directions and inhomogeneous with respect to the height coordinate. The surface waves in the substrate are analysed using the propagator technique and residue calculus. The propagators and the residues are found by solving two sets of systems of ordinary differential equations (ODEs). Several dispersion curves of the surface waves for inhomogeneous substrates are calculated. The radiation efficiency is compared with the corresponding quantities of a printed antenna on a homogeneous substrate.
|
|
| 9. |
- Sjöberg, Daniel, et al.
(författare)
-
A Floquet-Bloch decomposition of Maxwell's equations, applied to homogenization
- 2003
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Using Bloch waves to represent the full solution of Maxwell’s equations in periodic media, we study the limit where the material’s period becomes much smaller than the wavelength. It is seen that for steady-state fields, only a few of the Bloch waves contribute to the full solution. Effective material parameters can be explicitly represented in terms of dyadic products of the mean values of the non-vanishing Bloch waves, providing a new means of homogenization. The representation is valid for an arbitrary wave vector in the first Brillouin zone.
|
|
| 10. |
|
|
