| 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)
-
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
-
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
-
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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| 11. |
- Ellgardt, Anders, et al.
(författare)
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Edge element evaluation of tapered-slot elements in phased arrays
- 2010
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Ingår i: EuCAP 2010 - The 4th European Conference on Antennas and Propagation. - 9781424464319
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Konferensbidrag (refereegranskat)abstract
- The edge elements in large phased arrays of tapered-slot elements are analyzed and compared with the infinite array. In large phased arrays the elements that are close to the center of the antenna have similar performance. However, the elements close to an edge will have different coupling coefficients and embedded radiation patterns due to the truncated geometry. In this paper the edge effects in a triangular grid tapered-slot array is studied by using finite-by-infinite arrays. The array is infinite in the direction along the edge and finite in the other direction. The S-parameters for three truncations of the tapered slot element are compared with the infinite array solution for the case when the edge is orthogonal to the E-plane.
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| 12. |
- Fhager, Andreas, 1976, et al.
(författare)
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Clinical Diagnostics and Treatment with Electromagnetic Fields
- 2010
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Ingår i: 4th European Conference on Antennas and Propagation, EuCAP 2010; Barcelona; Spain; 12 April 2010 through 16 April 2010. - 9788476534724 ; , s. C15P2-1
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Konferensbidrag (refereegranskat)abstract
- There is a need for novel diagnostic and treatment systems to overcome the limitations with todays modalities. Microwave and THz based system has the potential to become both sensitive and specific in several applications. In this paper we discuss several applications that are currently being developed at the Chalmers University of Technology.
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| 13. |
- Fhager, Andreas, 1976, et al.
(författare)
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Stroke Detection Using a Broad Band Microwave Antenna System
- 2010
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Ingår i: EUCAP2010, 4th European Conference on Antennas and Propagation, April 12-16, Barcelona, Spain. - 9788476534724 ; , s. C13P1-2
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- In this paper we describe a microwave based measurement setup and a signal processing algorithm for stroke detection and diagnostics.
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| 14. |
- Gustafson, Carl, et al.
(författare)
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Archimedean spiral antenna for underground soil measurements in Greenland
- 2010
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Ingår i: [Host publication title missing]. - 9781424464319
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Konferensbidrag (refereegranskat)abstract
- In this paper, we present a thin single-arm Archimedean spiral antenna designed to be used in underground soil measurements to characterize the dielectric properties of soil during freezing and thawing processes. The designed antenna works in low permittivity, low-loss frozen soil as well as in high permittivity, high-loss marshy soil and operates over the frequency range 1–3 GHz. The antennas has been successfully used for measurements of soil properties in situ.
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| 15. |
- He, Sailing, et al.
(författare)
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Patch Antennas Based On a Pair of DPS and SNG Metamaterial
- 2010
-
Ingår i: EuCAP 2010 - The 4th European Conference on Antennas and Propagation. - 9788476534724
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- In this talk we show some potential applications of a pair of conventional double positive (DPS) and single negative (SNG) metamaterial blocks for specific patch antennas. We propose two designs. One is a 900- and 1800-MHz dual-band rectangular patch antenna filled with a pair of juxtaposed DPS and mu-negative (MNG) metamaterial blocks. With proper constitutive parameters and filling ratio of the material blocks, the conventional TM(020) mode is modified and broadside radiation pattern can be simultaneously achieved at both bands. The other is a two-layered rectangular patch antenna, with a bilayer of DPS and epsilon-negative (ENG) metamaterial as its substrate. Due to the super-slow TM surface wave mode that the bi-layer structure supports, the size of the patch antenna is substantially reduced as compared to conventional lambda/2 patch antennas.
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| 16. |
- Jamaly, Nima, 1979, et al.
(författare)
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Performance of directive multi-element antennas versus multi-beam arrays in MIMO communication systems
- 2010
-
Ingår i: EuCAP 2010 Fourth European Conference on Antennas and Propagation, Barcelona, 12-16 April 2010. - 9781424464319
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Konferensbidrag (refereegranskat)abstract
- In an isotropic rich scattering environment, the shape of the patterns of the elements has long been considered as irrelevant to their Multiple-Input and Multiple-Output (MIMO) performances. In the current communication it is cleared that the directivities of the embedded elements, which are immediate outcomes of their patterns, contribute to the diversity gains as well as capacity of the system. Indeed, the number of scatterers plays a significant role in this respect. It is demonstrated that unless the number of scatterers is high enough, the diversity gain and capacity do not reach their final limits, even though the spatial correlation and radiation efficiencies reside on their ideally best levels. A brief study of the matter is presented in this paper and the simulation results are verified by measurements in reverberation chamber.
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| 17. |
- Karandikar, Yogesh, 1982
(författare)
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Comparisons of different descrambler/ power combining boards layout for multi-port, decade bandwidth Eleven feed
- 2010
-
Ingår i: 4th European Conference on Antennas and Propagation, EuCAP 2010; Barcelona; Spain; 12 April 2010 through 16 April 2010. - 9788476534724 ; , s. Art. no. 5505128-
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Konferensbidrag (refereegranskat)abstract
- Eleven feed based on parallel folded dipole log-periodic arrays has four differential ports above ground plane. This paper presents different possibilities of combining these ports below ground plane so as to have two unbalanced ports for orthogonal linear polarizations. Also the various ways of combining LNA in these boards is discussed. For radio astronomy applications, where lowest noise is desired, the use of differential LNA and further passive power combining is justified as best possible choice.
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| 18. |
- Karandikar, Yogesh, 1982, et al.
(författare)
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Reduction of radiation from central exciting region of Eleven feed and pattern improvements for VLBI 2010 applications
- 2010
-
Ingår i: EuCAP 2010 Fourth European Conference on Antennas and Propagation, Barcelona, 12-16 April 2010. - 9788476534724 ; , s. Art. no. 5505151-
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Konferensbidrag (refereegranskat)abstract
- Multiport, decade bandwidth Eleven feed for prime focus reflector is ongoing development for VLBI 2010 applications. Current version of this feed uses four differential lines used to excite the log-periodic arrays above ground plane. These excitation lines packaged in small central region referred as centre puck shows radiation from lines above 10GHz causing distortion in feed pattern. This paper focuses on these radiations from exciting structures and proposes new methods to efficiently excite log-periodic arrays of Eleven feed while minimizing the radiation losses.
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| 19. |
- Karlsson, Kristian, et al.
(författare)
-
Non-foster networks for improvement of radiation efficiency and effective diversity gain of a multi-port antenna
- 2010
-
Ingår i: EuCAP 2010 - The 4th European Conference on Antennas and Propagation. - 9788476534724
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Konferensbidrag (refereegranskat)abstract
- The use of non-Foster components in wideband matching networks for improvement of effective diversity gain and total radiation efficiency of a multi-port antenna is studied. The frequency response of an optimized wideband matching network is first derived, and afterwards synthesized with real circuit components. As the required reactance slope of the realized components often turns out to be negative for both single and multi-port wideband antennas, the possibility to use negative capacitors and inductors (i.e. non-Foster components) is investigated. To exemplify this, two inverted L-antennas (bended monopoles) on a mobile phone sized ground plane is studied.
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| 20. |
- Li, Hui, et al.
(författare)
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High isolation compact four-port MIMO antenna systems with built-in filters as isolation structure
- 2010
-
Ingår i: Proceedings of the Fourth European Conference on Antennas and Propagation. - : Institute of Electrical and Electronics Engineers (IEEE). - 9788476534724
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Konferensbidrag (refereegranskat)abstract
- In this work, we present a built-in filter method to enhance the isolation level between closely packed MIMO antennas. The built-in filter is composed of several slits etched on the ground of the antenna structure. The number and length of slits depend on both the resonance frequency and the structure of the MIMO antenna system. To illustrate its usefulness, two designs of compact planar four-port MIMO antenna systems with built-in filters are proposed. One MIMO system is composed of different types of antennas with similar radiation characteristics, such as polarization. The lateral size of the whole system is 0.64λ×0.48λ. To further reduce the size of the MIMO structure, polarization diversity is utilized in the second example. The dimension is only 0.4λ×0.4λ. In both cases, with the built-in filters, the isolation level can be improved by 10dB. In both MIMO systems, the measured port isolations between antennas are below -25dB, and the envelope correlations are smaller than 0.04, indicating good MIMO performance.
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| 21. |
- Polemi, A., et al.
(författare)
-
Approximated closed form characteristic impedance for the bed of nails-based gap waveguide
- 2010
-
Ingår i: EuCAP 2010 Fourth European Conference on Antennas and Propagation, Barcelona, 12-16 April 2010. - 9781424464319
-
Konferensbidrag (refereegranskat)abstract
- The parallel-plate ridge gap waveguide has been introduced recently. It consists of a metal ridge in a metamaterial magnetic conductor surface, covered by a metallic plate at a small height above it. The metamaterial surface is designed to provide a frequency band where parallel-plate modes are in cut-off, thereby allowing for a conned gap wave to propagate along the ridge. In this paper, the investigation upgrades the analytical expression of the modal dispersion equation given previously, by including the first higher order mode. Furthermore, the characteristic impedance of the dominant mode is analytically calculated, by means of three different closed form expressions.
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| 22. |
- Pucci, Elena, 1982, et al.
(författare)
-
Losses in ridge gap waveguide compared with rectangular waveguide and microstrip lines
- 2010
-
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 study and quantification of losses in ridge gap waveguide, compared to losses in ideal standard rectangular waveguide and microstrip transmission line is presented. The study is performed by evaluating the quality factor of resonators made of ridge gap waveguide, rectangular waveguide and microstrip line. Results will show that the ridge gap waveguide has a very low loss.
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| 23. |
- Rajo, Eva, 1972, et al.
(författare)
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Groove gap waveguide - A rectangular waveguide between contactless metal plates enabled by parallel-plate cut-off
- 2010
-
Ingår i: EuCAP 2010 Fourth European Conference on Antennas and Propagation, Barcelona, 12-16 April 2010. - 9788476534724
-
Konferensbidrag (refereegranskat)abstract
- This work presents a numerical study of a topology of gap waveguide referred to as groove-type gap waveguide, including dispersion diagrams and field distributions for different groove geometries. The main difference between this groove gap waveguide and the ordinary rectangular waveguides is that there is no need of electrical contact between upper and lower plate constituting the waveguide. This is a clear advantage at high frequencies when designing cavity filters and other components which require the fabrication of the waveguide based on two pieces and consequently requiring a large number of screws to ensure good conducting contact and avoid leakage.
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| 24. |
- Thiel, Andreas, et al.
(författare)
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In-situ vehicular antenna integration and design aspects for vehicle-to-vehicle communications
- 2010
-
Ingår i: [Host publication title missing]. - 9781424464319 ; , s. 1-5
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Konferensbidrag (refereegranskat)abstract
- Vehicle-to-vehicle (V2V) communications aim to enhance driver safety and traffic efficiency by using the recently designated frequency bands in the 5.9 GHz range in Europe. Due to the time-frequency selective fading behavior of the vehicular communication channel, multi-antenna techniques can provide enhanced link conditions by means of diversity processing. This paper highlights the integration of a four-element (N =4) linear array antenna into the roof-top compartment of a vehicle to conduct Multiple-Input Multiple-Output (MIMO) high-resolution mobile-to-mobile channel measurements.
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| 25. |
- Uz Zaman, Ashraf, 1975, et al.
(författare)
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Validation of ridge gap waveguide performance using in-house TRL calibration kit
- 2010
-
Ingår i: EuCAP 2010 Fourth European Conference on Antennas and Propagation, Barcelona, 12-16 April 2010. - 9781424464319
-
Konferensbidrag (refereegranskat)abstract
- In this work, the low-loss performance of the recently evolved ridge gap waveguide technology has been demonstrated. A TRL calibration kit was designed to do the calibration of the manufactured ridge gap waveguide demonstrator. The calibrated S-parameters for the gap waveguide demonstrator are presented in this work and it is verified that the ridge gap waveguide work according to simulations with wide bandwidth and low loss. The loss of the gap waveguide section was found to be so low that it cannot be quantified for the chosen waveguide length due to measurement uncertainties arising from imperfect connectors, possible imperfections in standards of the TRL kit due to manufacturing tolerance, VNA random errors etc.
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| 26. |
- Yang, Jian, 1960, et al.
(författare)
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Comparison of two decade bandwidth feeds for reflector antennas: Eleven antenna and quadridge horn
- 2010
-
Ingår i: EuCAP 2010 Fourth European Conference on Antennas and Propagation, Barcelona, 12-16 April 2010. - 9781424464319
-
Konferensbidrag (refereegranskat)abstract
- This paper presents a comparison the Eleven Antenna and the ETS-Lindgren quadridge horn in terms of their radiation performance as feeds for reflector antennas. They are both candidates for feeding future radio telescopes for Square Kilometer Array and VLBI2010. The comparison is done by processing measured radiation field functions and input reflection coefficients of both antennas to determine expected reflector antenna performance
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| 27. |
- Zeng, Xuezhi, 1980, et al.
(författare)
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Study on the sensitivity of image reconstruction to the measurement uncertainty in microwave tomography
- 2010
-
Ingår i: EuCAP 2010 - The 4th European Conference on Antennas and Propagation. - 9788476534724
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Konferensbidrag (refereegranskat)abstract
- We investigated the effects of measurement uncertainty on the image reconstructions for different breast models. Three different contrast levels between the background tissue and tumor were chosen. It was shown that the reconstruction of lower contrast breast model was more sensitive to the measurement uncertainty. For a breast model with contrast as low as 1.1 : 1, an amplitude uncertainty of 0.2 dB or a phase uncertainty of 2 degrees would result in an unsuccessful reconstruction.
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