| 1. |
- Gustafsson, Mats, et al.
(författare)
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Constraints on the temporal dispersion of metamaterials
- 2010
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Ingår i: Proceedings of the Fourth European Conference on Antennas and Propagation. - 9781424464319 - 9788476534724 ; , s. 1-3
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Konferensbidrag (refereegranskat)abstract
- The frequency dependence of the permittivity, permeability, and index of refraction restrict metamaterial applications such as cloaking and perfect lenses. Here, the principles of causality and passivity together with identities for Herglotz functions are used to construct various sum rules. The sum rules relate the frequency dependence of the material parameters with their high- and low-frequency values. The corresponding physical bounds determine minimum variations of the material parameters over a frequency interval.
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| 2. |
- Haneda, Katsuyuki, et al.
(författare)
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Measurement of loop-back interference channels for outdoor-to-Indoor full-duplex radio relays
- 2010
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Ingår i: Proceedings of the Fourth European Conference on Antennas and Propagation. - 9788476534724 - 9781424464319
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Konferensbidrag (refereegranskat)abstract
- A full-duplex relay enhances the end-to-end spectral efficiency compared to a half-duplex relay, provided that the loop-back interference at relays is managed well. In order to study the feasibility of the full-duplex relay, it is crucial to measure and model the loop-back interference channels. This paper presents a measurement campaign of these channels for outdoor-to-indoor communications. A compact relay antenna was developed to serve as a signal repeater between outdoor base stations and indoor users, and was used for the loop-back interference channel measurement. Measurement results revealed that the mean interference level was -48 dB in the compact relay antenna, and it could be further reduced by placing the outdoor and indoor antennas in a different position referred to as a separate relay. Combined with an appropriate countermeasure to reduce the interference level, such as an interference canceller, the full-duplex operation of indoor compact relay terminal was found to be feasible.
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| 3. |
- Hult, Tommy, et al.
(författare)
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Analytical dual-link MIMO channel model using correlated correlation matrices
- 2010
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Ingår i: Proceedings of the Fourth European Conference on Antennas and Propagation. - 9788476534724 - 9781424464319
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Konferensbidrag (refereegranskat)abstract
- Analytical Multiple-Input Multiple-Output (MIMO) models are often attractive due to their low complexity when analyzing possibilities and limitations in the system. In this paper we outline a a possible dual link extension of an analytical MIMO channel model and investigate its suitability based on measurements of a dual link MIMO scenario. The extension is based on the correlation matrix distance (CMD) as a gauge to generate correlation matrices for the additional links of the multi-link scenario.
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| 4. |
- Javashvili, Otar, et al.
(författare)
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New method for design implementation of Vivaldi antennas to improve its UWB behaviour (EuCAP 2010)
- 2010
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Ingår i: Proceedings of the Fourth European Conference on Antennas and Propagation. - 9781424464319 - 9788476534724
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Konferensbidrag (refereegranskat)abstract
- The aim of this paper is to investigate the parameters of one of the UWB Sensors, called Vivaldi Antenna, and to propose the new ways how they can be improved. As a practical implementation of the sensor, the UWB radar for wall penetrating applications with impulse excitation was utilized. For wall penetration low frequency (0.3 – 8 GHz) supporting UWB signals are required. Within the scope of this project, the Vivaldi antenna parameters are improved in order to optimize the radiation bandwidth with an usable gain response along the whole operating band, including lower frequencies. It also automatically leads to the optimization of the size of the antenna. In addition, an investigation of the phase linearity and UWB behavior of the antenna was carried out.
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| 5. |
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| 6. |
- Larsson, Christer, et al.
(författare)
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Calibration methods for wideband forward RCS measurements
- 2010
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Ingår i: Proceedings of the Fourth European Conference on Antennas and Propagation. - 9781424464319 - 9788476534724 ; , s. 1-5
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Konferensbidrag (refereegranskat)abstract
- Calibration is an important part in all radar cross section measurements. Two different approaches to the calibration of forward and extinction cross section measurements are therefore evaluated and discussed in this paper. The first method is the commonly used calibration method employing a calibration target with a known cross section while the second calibration method does not require a calibration target. It is concluded that the method utilizing a calibration target is the most accurate method of the two.
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| 7. |
- Poutanen, Juho, et al.
(författare)
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Significance of common scatterers in multi-link indoor radio wave propagation
- 2010
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Ingår i: Proceedings of the Fourth European Conference on Antennas and Propagation. - 9781424464319 - 9788476534724
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Konferensbidrag (refereegranskat)abstract
- Correlation between different links is an essential characteristic for many of the forthcoming radio communication systems that utilize the multiple-input-multiple-output (MIMO) technology. This paper investigates the physical phenomena that cause the inter-link correlation by introducing a measure to quantify how large amount of energy propagates via similar propagation mechanisms in different links. The conditions for the so-called significance of common scatterers are derived and two dynamic dual-link indoor MIMO channel measurements are used to provide experimental results. The present work forms the indispensable basis for the channel modeling of multiuser MIMO communications.
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| 8. |
- Alfonso, E., et al.
(författare)
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Power divider in ridge gap waveguide technology
- 2010
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Ingår i: EuCAP 2010 Fourth European Conference on Antennas and Propagation, Barcelona, 12-16 April 2010. - 9781424464319
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Konferensbidrag (refereegranskat)abstract
- A power divider in ridge gap waveguide technology has been designed to work at 15GHz. Measurements and simulations are provided. Besides, a broad numerical study of the characteristic impedance of a ridge gap waveguide is presented.
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| 9. |
- Bosiljevac, M., et al.
(författare)
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Efficient spectral domain Green's function analysis of novel metamaterial bandgap guiding structures
- 2010
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Ingår i: EuCAP 2010 Fourth European Conference on Antennas and Propagation, Barcelona, 12-16 April 2010. - 9781424464319
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Konferensbidrag (refereegranskat)abstract
- The Green's function analysis of oversized waveguides with one wall realized as a periodic structure is presented in this paper. Two different realizations of the periodic structures were considered: the bed-of-nails surface and the mushroom surface. Since the period of these surfaces is small compared to wavelength it is possible to take advantage of the asymptotic boundary conditions in the derivation of the required Green's functions. By doing so, we avoid the usual Floquet mode approach needed in the analysis of periodic surfaces and significantly reduce the overall numerical complexity. The Green's functions developed in this way allow dispersion and electromagnetic field analysis since their poles correspond to surface wave modes and waveguide modes. These results reveal the dispersion characteristics of the observed structures and the bandwidth usable in the waveguide applications. The computed results are compared with the results obtained with a general electromagnetic solver and the agreement is very good.
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| 10. |
- Dobsicek Trefna, Hana, 1979, et al.
(författare)
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Time-reversal system for microwave hyperthermia
- 2010
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Ingår i: EuCAP 2010 - The 4th European Conference on Antennas and Propagation. - 9788476534724 ; , s. Art. nr. 5505231-
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Konferensbidrag (refereegranskat)abstract
- Hyperthermia is presently used as an adjuvant to the radiation therapy in the treatment of certain types of cancers. Recently, many randomised trials have shown a significant advantage of addition of hyperthermia combined with radiotherapy and/or chemotherapy in the treatment of solid tumours. This paper presents the first experimental results obtained with a prototype of a new system for microwave hyperthermia based on time-reversal algorithm. The level of absorbed energy is strongly dependent on size of treated area through penetration depth of EM waves, thus selection of the frequency depends on treated area sizes as well as tumour volume. The system has thus been designed to work at broad frequency range.
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