| 31. |
- Sjöberg, Daniel, et al.
(författare)
-
A physical bound on high impedance surfaces
- 2010
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Ingår i: [Host publication title missing]. ; , s. 393-396
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Konferensbidrag (refereegranskat)abstract
- A high surface impedance can be achieved in a limited frequency band by using composite structures. Based on the principles of causality, passivity, linearity, and time translational invariance we demonstrate that this bandwidth is bounded by the thickness and magnetic polarizability per unit area of the structure at normal incidence.
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| 32. |
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| 33. |
- Sjöberg, Daniel, et al.
(författare)
-
All-spectrum oblique transmission through a periodic screen
- 2010
-
Ingår i: [Host publication title missing]. ; , s. 764-767
-
Konferensbidrag (refereegranskat)abstract
- We show that the all-spectrum transmission blockage through a low-pass screen is bounded by the static polarizability per unit area of the screen, irrespective of how complicated the materials involved are. The angular dependence at oblique incidence is investigated, and the results are verified by measurements on an array of split ring resonators.
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| 34. |
- Sjöberg, Daniel, et al.
(författare)
-
Convex optimization for optimal realization of material properties
- 2014
-
Ingår i: 2014 International Conference on Electromagnetics in Advanced Applications (ICEAA), 3-8 Aug. 2014, Palm Beach. - : IEEE Press. - 9781479973255 ; , s. 782-785
-
Konferensbidrag (refereegranskat)abstract
- We show how the best passive approximation to a given target material or structure can be found byconvex optimization. The approach is based on a representation of positive real functions, where some of the parameters can be given physical relevance by comparison to low- and high-frequency asymptotics of the material or structure under study. A number of different optimization problems can be formulated, which generalizes previous approaches using sum rules.
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| 35. |
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| 36. |
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| 37. |
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| 38. |
- Sjöberg, Daniel, et al.
(författare)
-
On the quality factor of a low-loss parallel-plate resonator based on complementary metamaterials
- 2011
-
Konferensbidrag (refereegranskat)abstract
- Several proposals have been made during the last ten years on size-independent resonators by using metamaterials for phase compensation. In this paper, we present an estimate of the quality factor of a simple parallel-plate resonator, based on realistic assumptions such as linear, passive, causal, time-translational invariant metamaterials, and lossy walls. It is found that the quality factor of the resonator depends on whether the losses of the material or the metal walls are dominating: in the former case, there is no size dependence, in the latter case, the size dependence is similar to a vacuum-lled resonator.
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| 39. |
- Sjöberg, Daniel, et al.
(författare)
-
Physical bounds on the all-spectrum transmission through periodic arrays: oblique incidence
- 2010
-
Ingår i: Europhysics Letters. - : IOP Publishing. - 0295-5075. ; 92, s. 1-34009
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- The performance of a low-pass screen designed to block electromagnetic waves in a stop-band is shown to have an upper bound defined by the static electric and magnetic polarizability per unit area of the screen. The bound is easy to calculate for all angles of incidence and polarizations, and applies regardless of how complicated the screen's microstructure is. For a homogeneous dielectric sheet the bound for TM polarization is more restrictive than the bound for TE, but this is not generally true for a screen with microstructure. The results are verified by measurements and simulations of oblique transmission through an array of split ring resonators, printed on a dielectric substrate.
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| 40. |
- Sjöberg, Daniel, et al.
(författare)
-
Realization of a matching region between a radome and a ground plane
- 2010
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Ingår i: Progress In Electromagnetics Research Letters. - 1937-6480. ; 17, s. 1-10
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- In order to reduce the monostatic signature of the junction between a radome and the metallic structure to which it is attached, a tapered resistive sheet can be used. In this paper, we describe an easy method to realize this tapering using geometric variations on a subwavelength scale, with a significant reduction of the number of processing steps as a result.
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