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Lindgren, Tore
Publications (10 of 23) Show all publications
Lindgren, T. & Borg, J. (2012). A measurement system for the position and phase errors of the elements in an antenna array subject to mutual coupling (ed.). International Journal of Antennas and Propagation, 2012, Article ID 526121.
Open this publication in new window or tab >>A measurement system for the position and phase errors of the elements in an antenna array subject to mutual coupling
2012 (English)In: International Journal of Antennas and Propagation, ISSN 1687-5869, E-ISSN 1687-5877, Vol. 2012, article id 526121Article in journal (Refereed) Published
Abstract [en]

When deploying large antenna arrays in arctic environments, a local measurement system may be necessary in order to ensure control over the position and phase of the individual antenna elements. In this paper, a method of estimating the position and phase of each individual antenna element in the presence of mutual coupling is presented. It uses both measurements of the scattering matrix in the array and measurements of the electric field using a minimum of four probes located in the near field of the array. Simulations show that the method gives accurate results even in the presence of noise in the measurements. The geometry of the probe-array system affects the performance significantly.

National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Research subject
Industrial Electronics
Identifiers
urn:nbn:se:ltu:diva-3767 (URN)10.1155/2012/526121 (DOI)000301411200001 ()2-s2.0-84858300196 (Scopus ID)198f5821-7dde-4b65-b0ef-53e38537fb1c (Local ID)198f5821-7dde-4b65-b0ef-53e38537fb1c (Archive number)198f5821-7dde-4b65-b0ef-53e38537fb1c (OAI)
Note

Validerad; 2012; 20111205 (tore)

Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-07-10Bibliographically approved
Isoz, O., Akos, D., Lindgren, T., Sun, C.-C. & Jan, S.-S. (2011). Assessment of GPS L1/Galileo E1 interference monitoring system for the airport environment (ed.). In: (Ed.), (Ed.), Proceedings of the 23rd international technical meeting of the Satellite Division of the Institute of Navigation, ION GNSS 2011: Sept. 19 - 23, 2011, Oregon Convention Cener, Portland, Oregon. Paper presented at ION GPS GNSS : 19/09/2011 - 23/09/2011 (pp. 1920-1930). Manassas, Va: Inst. of Navigation, 3
Open this publication in new window or tab >>Assessment of GPS L1/Galileo E1 interference monitoring system for the airport environment
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2011 (English)In: Proceedings of the 23rd international technical meeting of the Satellite Division of the Institute of Navigation, ION GNSS 2011: Sept. 19 - 23, 2011, Oregon Convention Cener, Portland, Oregon, Manassas, Va: Inst. of Navigation , 2011, Vol. 3, p. 1920-1930Conference paper, Published paper (Refereed)
Abstract [en]

How does the GPS Ll spectrum look like at a commercial airport? How frequently do radio frequency interference (RFI) incidents occur? To answer this, the GPS Ll/Galileo El band was monitored at two different airports for an extended period of time. The monitor stations continuously recorded the noise level using the automatic gain control (AGC) in the frontend. Also, the raw intermediate frequency (IF) signal was recorded at regular intervals as well as when the AGC level dropped below a certain threshold. In this paper the analysis of long-term measurements of the spectrum and AGC level at Luleå Airport outside Luleå, Sweden, and Kaohsiung International Airport in Kaohsiung City, Taiwan, is presented. The results shows that RFI incidents did occur at both airports, although more frequent at Kaohsiung International Airport. The measurements also show that the AGC level is useful in systems monitoring the RFI environment. Importantly, the measured data could be utilized for analyses toward the future introduction of GBAS for civil aviation authorities.

Abstract [en]

How does the GPS L1 spectrum look like at a commercial airport? How frequently do radio frequency interference (RFI) incidents occur? To answer this, the GPS L1/Galileo E1 band was monitored at two different airports for an extended period of time. The monitor stations continuously recorded the noise level using the automatic gain control (AGC) in the frontend. Also, the raw intermediate frequency (IF) signal was recorded at regular intervals as well as when the AGC level dropped below a certain threshold. In this paper the analysis of long-term measurements of the spectrum and AGC level at Luleå Airport outside Lueå Sweden, and Kaohsiung International Airport in Kaohsiung City, Taiwan, is presented. The results shows that RFI incidents did occur at both airports, although more frequent at Kaohsiung International Airport. The measurements also show that the AGC level is useful in systems monitoring the RFI environment. Importantly, the measured data could be utilized for analyses toward the future introduction of GBAS for civil aviation authorities.

Place, publisher, year, edition, pages
Manassas, Va: Inst. of Navigation, 2011
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Research subject
Industrial Electronics
Identifiers
urn:nbn:se:ltu:diva-27335 (URN)0c059292-cbd3-4d09-beda-8e9e5de8108b (Local ID)9781618394750 (ISBN)0c059292-cbd3-4d09-beda-8e9e5de8108b (Archive number)0c059292-cbd3-4d09-beda-8e9e5de8108b (OAI)
Conference
ION GPS GNSS : 19/09/2011 - 23/09/2011
Note
Godkänd; 2011; Bibliografisk uppgift: 1 CD-ROM; 20111021 (osciso)Available from: 2016-09-30 Created: 2016-09-30 Last updated: 2017-11-25Bibliographically approved
Ekman, J., Lindgren, T. & Wickramanayake, A. (2011). Project: Improved measurements of mining induced ground deformations using GPS and SAR techniques. Paper presented at .
Open this publication in new window or tab >>Project: Improved measurements of mining induced ground deformations using GPS and SAR techniques
2011 (English)Other (Other (popular science, discussion, etc.))
Abstract [en]

The LKAB SAR project is implemented to measure the subsidence and terrain deformation around the Kiruna iron ore mine and in the Kiruna city area. The LKAB SAR project has two components. One is the monitoring component in which MDA (main contractor) provides the SAR deformation maps to LKAB and the second is the technology transfer component in where MDA provides theoretical and practical knowledge to LKAB so that LKAB can produce deformation maps by their own. And Cranfield University and Luleå University of technology will carryout the LKAB SAR research. During the SAR project it is expected to use “DInSAR” and “CTM” techniques to measure the deformations. By using DInSAR and CTM techniques, LKAB can achieve the required accuracy levels during the summer season but it is likely that the quality and quantity of the measurements will largely differ during winter season (due to the thick snow cover). Similarly, areas which have thick forest cover will prevent radar waves reaching the ground and because of that it is likely the quality and quantity of the measurements will decrease in such areas during the mid summer period. Therefore LKAB is planning to carry out a research program to improve the SAR measurements.

National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Research subject
Industrial Electronics
Identifiers
urn:nbn:se:ltu:diva-36180 (URN)9c48f137-9df6-438e-98a5-8ea304cdd290 (Local ID)9c48f137-9df6-438e-98a5-8ea304cdd290 (Archive number)9c48f137-9df6-438e-98a5-8ea304cdd290 (OAI)
Note

Publikationer: Seasonal Variation of Coherence in SAR Interferograms in Kiruna, Northern Sweden; Mine induced deformation measurements using SAR interferometry at high latitudes; Status: Ongoing; Period: 15/08/2009 → 15/08/2013; End date: 15/08/2013

Available from: 2016-09-30 Created: 2016-09-30 Last updated: 2017-11-25Bibliographically approved
Hobbs, S., Wickramanayake, A., Sjöberg, J., Lindgren, T., Henschel, M. & Fernando, P. (2011). SAR inteferometry with seasonally changing snow cover (ed.). Paper presented at International Workshop on "Advances in the Science and Applications of SAR Interferometry" : FRINGE 2011 Workshop 19/09/2011 - 23/09/2011. Paper presented at International Workshop on "Advances in the Science and Applications of SAR Interferometry" : FRINGE 2011 Workshop 19/09/2011 - 23/09/2011.
Open this publication in new window or tab >>SAR inteferometry with seasonally changing snow cover
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2011 (English)Conference paper, Oral presentation only (Refereed)
Abstract [en]

Spaceborne radar interferometry is an established and very powerful method of measuring land subsidence over timescales of weeks to years. It has been demonstrated on natural and urban landscapes and is becoming an operational technique with accuracy better than 1 cm yr-1. The technique generally relies on having scatterers (which reflect the radar signal) which have stable properties over the timescale of interest. In some landscapes these scatterers occur naturally. However, at high latitudes there are particular difficulties because of the strong seasonal variation in the landcover – snow cover in particular can vary dramatically over periods of weeks to months – and the satellite orbits have particular features which are not generally significant at lower latitudes. It is unlikely that natural scatterers will be stable over long periods in these areas. The aim of this project is to develop methods of SAR interferometry suitable for use in landscapes with seasonal snow cover. The project has two themes: (1) improved understanding of SAR imaging at high latitudes and the use of interferometry in such landscapes, and (2) the development of artificial radar targets which can provide the necessary stability for long-term surface deformation monitoring. The sponsor runs a large mining operation at high latitudes. The study has a practical focus and is part of a larger project to provide a mining subsidence monitoring service for the sponsor. The project’s aim is to achieve accurate monitoring of subsidence using radar interferometry at high latitudes. Techniques developed should be suitable for operational use. Test site The experiment test site is centred on the town of Kiruna in northern Sweden (67° 51’ N, 20° 13’ E). The ground is covered with snow (to a depth of 1 m or more) from October to May each year, and so the winter and summer periods have very different land cover properties. The site includes the town of Kiruna, a large mine, and areas of natural sparse forest with mainly birch and some coniferous trees up to several metres tall. Datasets Available Several datasets are available to support the research, these include: • GPS measurements from a network of control points • General weather observations • Mapping data for land cover / land use and topography • SAR images at approximately monthly intervals from 2009 (Radarsat-2, using up to 3 satellite tracks for imaging) • A network of corner reflectors across the test area The core data analysis tool is the MDA software package designed for processing Radarsat images (for both backscatter and interferometric products). The key resource for the research is the time series of high resolution SAR images suitable for interferometric processing, which allows seasonal changes in backscatter to be observed directly. Methodology The project requires a mix of simulation and practical design and fieldwork. The main contributions will be in the area of target specification, design and validation. Achievements to date The project started late in 2009 and the main emphasis so far has been to establish the datasets needed for the research. Radarsat-2 images have been acquired and are being processed to derive interferometric products and to register them to standard projections compatible with each other and ancillary data. Field observations complementing the satellite imaging are also being made. Acknowledgements The project is sponsored in full by the LKAB mining company.The project also benefits from technical advice of MDA.

National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Research subject
Industrial Electronics
Identifiers
urn:nbn:se:ltu:diva-39424 (URN)e2ee2478-d6aa-4aad-ade1-52c1282b4812 (Local ID)e2ee2478-d6aa-4aad-ade1-52c1282b4812 (Archive number)e2ee2478-d6aa-4aad-ade1-52c1282b4812 (OAI)
Conference
International Workshop on "Advances in the Science and Applications of SAR Interferometry" : FRINGE 2011 Workshop 19/09/2011 - 23/09/2011
Note
Godkänd; 2011; 20111205 (tore)Available from: 2016-10-03 Created: 2016-10-03 Last updated: 2017-11-25Bibliographically approved
Lindgren, T. (2011). Tradeoff between complexity and performance in measurement systems for large antenna arrays (ed.). Paper presented at International Symposium on Antennas and Propagation : 25/10/2011 - 28/10/2011. Paper presented at International Symposium on Antennas and Propagation : 25/10/2011 - 28/10/2011.
Open this publication in new window or tab >>Tradeoff between complexity and performance in measurement systems for large antenna arrays
2011 (English)Conference paper, Oral presentation only (Refereed)
Abstract [en]

n this paper different calibration methods for large antenna arrays subject to random errors in position and phase are compared. The results shows that the gain loss is reduced when more sophisticated calibration systems are used while the beam is broadned if the position error is measured using one probe.

National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Research subject
Industrial Electronics
Identifiers
urn:nbn:se:ltu:diva-38788 (URN)d49f1725-ba9c-4f07-9576-7b5430dafdc6 (Local ID)d49f1725-ba9c-4f07-9576-7b5430dafdc6 (Archive number)d49f1725-ba9c-4f07-9576-7b5430dafdc6 (OAI)
Conference
International Symposium on Antennas and Propagation : 25/10/2011 - 28/10/2011
Note
Godkänd; 2011; 20111205 (tore)Available from: 2016-10-03 Created: 2016-10-03 Last updated: 2017-11-25Bibliographically approved
Lindgren, T., Ekman, J. & Backén, S. (2010). A measurement system for the complex far-field of physically large antenna arrays under noisy conditions utilizing the equivalent electric current method (ed.). Paper presented at . IEEE Transactions on Antennas and Propagation, 58(10), 3205-3211
Open this publication in new window or tab >>A measurement system for the complex far-field of physically large antenna arrays under noisy conditions utilizing the equivalent electric current method
2010 (English)In: IEEE Transactions on Antennas and Propagation, ISSN 0018-926X, E-ISSN 1558-2221, Vol. 58, no 10, p. 3205-3211Article in journal (Refereed) Published
Abstract [en]

Precipitation in the form of snow or rain could severely degrade the performance of large antenna arrays, in particular if knowledge about the beam shape and pointing direction in absolute numbers is necessary. In this paper, a method of estimating the far-field of each individual antenna element using the equivalent electric current approach is presented. Both a least squares estimator and a Kalman filter was used to solve the resulting system of equation and their performance was compared. Simulation results shows that the estimated far-field for one antenna element is very accurate if there is no noise on the signal. During noisier conditions the Kalman filter gives less noisy results while the systematic errors are slightly larger compared to the least squares estimator.

National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Research subject
Industrial Electronics
Identifiers
urn:nbn:se:ltu:diva-9582 (URN)10.1109/TAP.2010.2055780 (DOI)000283364300013 ()2-s2.0-77957788608 (Scopus ID)83ac9ab0-5143-11df-a0f4-000ea68e967b (Local ID)83ac9ab0-5143-11df-a0f4-000ea68e967b (Archive number)83ac9ab0-5143-11df-a0f4-000ea68e967b (OAI)
Note
Validerad; 2010; 20100426 (tore)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-07-10Bibliographically approved
Lindgren, T. (2010). A partial element equivalent circuit (PEEC) and numerical electromagnetics code (NEC) interface toolbox for Matlab (ed.). Paper presented at . Luleå: Luleå tekniska universitet
Open this publication in new window or tab >>A partial element equivalent circuit (PEEC) and numerical electromagnetics code (NEC) interface toolbox for Matlab
2010 (English)Report (Other academic)
Place, publisher, year, edition, pages
Luleå: Luleå tekniska universitet, 2010. p. 31
Series
Technical report / Luleå University of Technology, ISSN 1402-1536
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Research subject
Industrial Electronics
Identifiers
urn:nbn:se:ltu:diva-25611 (URN)fe9e3cb0-5c01-11df-ab16-000ea68e967b (Local ID)978-91-7439-105-3 (ISBN)fe9e3cb0-5c01-11df-ab16-000ea68e967b (Archive number)fe9e3cb0-5c01-11df-ab16-000ea68e967b (OAI)
Note
Godkänd; 2010; 20100510 (tore)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2017-11-24Bibliographically approved
Wannberg, G., Andersson, H., Behlke, R., Belyey, V., Bergqvist, P., Borg, J., . . . Wolf, I. (2010). EISCAT_3D - a next-generation European radar system for upper atmosphere and geospace research (ed.). Radio Science Bulletin (332), 75-88
Open this publication in new window or tab >>EISCAT_3D - a next-generation European radar system for upper atmosphere and geospace research
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2010 (English)In: Radio Science Bulletin, ISSN 1024-4530, no 332, p. 75-88Article in journal (Refereed) Published
Abstract [en]

The EISCAT Scientifi c Association, together with a number of collaborating institutions, has recently completed a feasibility and design study for an enhanced performance research radar facility to replace the existing EISCAT UHF and VHF systems. This study was supported by EU Sixth-Framework funding. The new radar retains the powerful multi-static geometry of the EISCAT UHF, but will employ phased arrays, direct-sampling receivers, and digital beamforming and beam steering. Design goals include, inter alia, a tenfold improvement in temporal and spatial resolution, an extension of the instantaneous measurement of full-vector ionospheric drift velocities from a single point to the entire altitude range of the radar, and an imaging capability to resolve small-scale structures. Prototype receivers and beamformers are currently being tested on a 48-element, 224 MHz array (the "Demonstrator") erected at the Kiruna EISCAT site, using the EISCAT VHF transmitter as an illuminator.

National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Research subject
Industrial Electronics; Embedded System; Signal Processing
Identifiers
urn:nbn:se:ltu:diva-8203 (URN)6acc9980-8341-11de-8da0-000ea68e967b (Local ID)6acc9980-8341-11de-8da0-000ea68e967b (Archive number)6acc9980-8341-11de-8da0-000ea68e967b (OAI)
Note

Validerad; 2010; 20090807 (gustav_j)

Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-06-11Bibliographically approved
Kvarnström, B., Lindgren, T. & Ekman, J. (2010). Monte Carlo simulation of an radio frequency identification system with moving transponders using the partial element equivalent circuit method (ed.). Paper presented at . IET Microwaves, Antennas & Propagation, 4(12), 2069-2076
Open this publication in new window or tab >>Monte Carlo simulation of an radio frequency identification system with moving transponders using the partial element equivalent circuit method
2010 (English)In: IET Microwaves, Antennas & Propagation, ISSN 1751-8725, E-ISSN 1751-8733, Vol. 4, no 12, p. 2069-2076Article in journal (Refereed) Published
Abstract [en]

When designing an radio frequency identification system it is important to take both the position and the movement of the transponders into account. In this study, a simulation method that enables the description of a complete RFID system including moving and rotating transponders as well as a complex, industrial environment is presented. By using the partial element equivalent circuit method to calculate the magnetic field generated by the reader antenna and describing the transponders using a magnetic dipole, it is possible to use the Monte Carlo method to describe the dynamic behaviour of the complete system. The method is used in this study to describe the difference in performance between two different reader antennas and these results are also compared to measurements of similar systems operating in an industrial environment. The difference in performance between the two systems is similar in both the simulations and the measurements. A small discrepancy was seen between the results from the simulations and the measurements which is for the most part because of the limited read rate of the RFID systems used in the measurements.

National Category
Reliability and Maintenance Other Electrical Engineering, Electronic Engineering, Information Engineering
Research subject
Quality Technology and Management; Industrial Electronics
Identifiers
urn:nbn:se:ltu:diva-4776 (URN)10.1049/iet-map.2009.0414 (DOI)000285139200011 ()2-s2.0-78649927699 (Scopus ID)2c4cfb90-d2c0-11de-bae5-000ea68e967b (Local ID)2c4cfb90-d2c0-11de-bae5-000ea68e967b (Archive number)2c4cfb90-d2c0-11de-bae5-000ea68e967b (OAI)
Note
Validerad; 2011; 20091116 (bjokva)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-07-10Bibliographically approved
Lindgren, T. (2009). Characterization problems in radio measurement systems (ed.). (Doctoral dissertation). Paper presented at . Luleå: Luleå tekniska universitet
Open this publication in new window or tab >>Characterization problems in radio measurement systems
2009 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Radio measurement systems may have their performance significantly degraded due to environmental factors such as multipath, weather effects, and mechanical displacements. Characterization of these effects are therefore important in order to ensure functionality of the system. The characterization itself may also be the purpose of the system. This thesis contributes to the answer to the question of how to assess the effect of the environment on the propagation and reception of radio waves for three different applications.Traditionally the functionality of a radio measurement system has been assessed using either simulations assuming ideal conditions (e.g. free space) or measurements under controlled circumstances. There is no doubt that both these approaches are very useful when designing antennas and related hardware. In many applications it is also sufficient to assume ideal conditions and only use an a priori characterization. The applications considered in this thesis all operates in an environment that can be considered to be challenging. In these cases the environment needs to be taken into account in the design process of the system. Both simulations and measurement methods have been considered. The combination of electromagnetic simulation methods, such as the method of moments (MOM) or the partial element equivalent circuit (PEEC) method, with statistical methods, such as the Monte Carlo method, have been given special attention. The measurement systems considered, both for determining the performance of antennas and for detection of objects and transponders, are all assessed from a "challenging environment" point of view.The three application considered are multistatic radar using global navigation satellite systems (GNSS), measurement systems for antenna arrays in noisy conditions, and simulation of RFID systems with moving transponders. In the multistatic radar the focus is on detecting signals reflected in directions other than that of the primary reflection. The results shows that detecting these signals is possible even with the low signal levels involved. This is especially the case when reflecting objects are present which could scatter the signal in a specular way. By using the equivalent electric current method it is possible to estimate the complex far-field radiation pattern of antenna arrays even when the signals used have a low signal-to-noise ratio (SNR). This has been shown using simulation of a large antenna array and with measurements using a small array for GNSS receivers. When designing RFID systems it is important to be able to estimate the performance in terms of number of detected transponders with all movements of the transponders taken into account. This is possible by using a very simple model of the transponders (e.g. a magnetic dipole) in which case only one electromagnetic simulation is needed. This enables the use of the Monte Carlo method to take the random movements of the transponders into account using a low number of computations. The use of the PEEC method further enables a combined simulation of both the electromagnetic properties of the reader antenna and the electric functionality of the receiver circuit.Although the considered application are very different the obtained solutions are in many ways general. The fact that even the weak signals reflected in non-specular directions in a multi-static GNSS radar can be detected can be used in any application involving multi-path propagation or stray signals. The equivalent electric current method have here been considered for two radically different antenna arrays operating in a low SNR environment. Although the simulation approach chosen for the RFID simulations rely heavily on the simple magnetic dipole method it would work with any antenna at any frequency as long as the model of the antenna is sufficiently simple.

Place, publisher, year, edition, pages
Luleå: Luleå tekniska universitet, 2009. p. 166
Series
Doctoral thesis / Luleå University of Technology 1 jan 1997 → …, ISSN 1402-1544
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Research subject
Industrial Electronics
Identifiers
urn:nbn:se:ltu:diva-16972 (URN)0f5673a0-ca72-11de-b769-000ea68e967b (Local ID)978-91-7439-034-6 (ISBN)0f5673a0-ca72-11de-b769-000ea68e967b (Archive number)0f5673a0-ca72-11de-b769-000ea68e967b (OAI)
Note
Godkänd; 2009; 20091106 (tore); DISPUTATION Ämnesområde: Industriell elektronik/Industrial Electronics Opponent: Professor Zvonimir Sipus, University of Zagreb, Kroatien Ordförande: Docent Jonas Ekman, Luleå tekniska universitet Tid: Torsdag den 10 december 2009, kl 10.00 Plats: D 770, Luleå tekniska universitetAvailable from: 2016-09-29 Created: 2016-09-29 Last updated: 2017-11-24Bibliographically approved
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