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  • 1.
    Ahlbom, Fredrik
    KTH, School of Information and Communication Technology (ICT).
    Analysis of the Performance of Different DWDM FilterTechnologies for Mobile Fronthaul Applications2016Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In recent years, several studies and simulations have been made on changing the current Radio Access Network (RAN) architecture into a more centralized access network where the base band processing is done in a central oce (CO) instead of out by the antenna site. This new architecture is denoted as the mobile fronthaul and is planned to be in use for the coming 5G network. The studies that have been made so far suggest that the new architecture can reduce cost, power usage and latency which are important factors regarding environmental, economical and data transmission issues. Furthermore, the new architecture allows a smarter distribution of data for each sector covered by the antennas, reducing redundant data transmission and thus increases the data eciency. The disadvantage or challenge however is that some of the optical components will be transferred from the currently controlled environment in the CO to an uncontrolled outdoor environment at the antenna site, which may generate risks as these components may be sensitive to especially changes in temperature.

    In this master thesis, the optical performance of four di erent passive lter setups, using a thin lm lter (TFF), an arrayed waveguide grating (AWG) and an interleaver, has been studied and compared in order to nd the most suitable lter setup for the mobile fronthaul. These optical parameters include insertion loss, isolation, crosstalk, 3 dB passband, center wavelength drift and also bit error-rate (BER) which have all been measured over a temperature interval of -40-85oC. Moreover, the measurement results have been compared with results from simulations done with VPItransmissionmaker.

    From the measurement results, the TFF had a better optical performance and reliability compared to the AWG mainly due to a higher isolation and a lower BER penalty of 0.2 dB compared to 0.5-1.5 dB for the AWG. Considering data capacity and economical aspects for a more realistic mobile fronthaul scenario with 80 channels using dense wavelength division multiplexing (DWDM) however, the AWG connected to the interleaver is more benecial without risking negative a ects on trac performance.

  • 2.
    Anderson, Taurug
    KTH, School of Electrical Engineering (EES), Fusion Plasma Physics.
    Iterative Learning Control model for a Resistive Wall Mode Active Controller2013Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The EXTRAP T2R is a Reversed Field Pinch (RFP) device purposed to conduct magnetic confinement fusion research. Magnetic confinement works on the principle of isolating the hot plasma from the cool walls by locking in the plasma onto the magnetic field lines. Due to the generally unstable nature of plasma, the plasma column will shift off its centered position and encroach upon the cooling walls. To counteract this, a series of magnetic sensor coil are placed around the torus that serve as the input for another set of coils that will generate a magnetic field to force the plasma column back in place. This is a feedback mechanism that uses a Proportional-Integral-Derivative (PID) as the loop gain control mechanisms. While this was effective in stabilizing the system it was discovered that during the start up phase of the experiment there was a repeatable pattern of disturbance. As such it offers the opportunity to make use of a feedforward Iterative Learning Control (ILC) that could provide a much more precise stabilization and occlude the possibility of saturating the feedback coils. In this thesis an ILC system will be built upon the existing PID system, it will be modeled in MATLAB and SIMULINK then run to simulate and gauge its performance.

  • 3.
    Anusuya Thiruchelvan, Niveditha
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.
    Design of an antenna for automotive communication in FM band2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Antennas used for FM transmission in radio stations are too large and to fit in the same for vehicular communication is inconceivable, considering the dimensional aspects. The product “EVAM System” is used for automotive communication in emergency vehicles. This product uses FM band for transmission of traffic information to the surrounding vehicle. The FM antennas normally installed on the vehicles are used for reception. The radiation efficiency of these antennas is too low and VSWR is too large. Thus, the FM reception antennas reflect the power at large scale, damaging the product as a result. The main objective of this thesis is to design a low-profile antenna, which can be mounted on the emergency vehicle as demanded by H&E Solutions AB. In addition to the dimensional requirements, the antenna should also satisfy the specified performance characteristics. These specifications are explained in detail and a design that best suits the product is developed considering both dimensional and performance characteristics.

  • 4.
    Bharadwaj Sriram, Adhitya
    KTH, School of Electrical Engineering and Computer Science (EECS).
    Concealment Materials and Techniques for mm-Wave Advanced Antenna Systems2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    With theadventofthe5Gtechnologystandardforcommunication,itisesti-mated thataround50billiondevicesaroundtheworldwillbeinterconnectedunder thisstandard [1]. Thishaspromptedtheneedtoinvestigatenewma-terials, technologiesandmethodstoconcealantennasforpreservingtheaes-thetic valueofurbancenters,andpreventingtheseantennasystemsfrombeingidentifiedordamaged.Theaimofthisthesisworkwastoidentifypossiblematerials andinvestigatemethodsforconcealingEricsson’s5Gmm-WaveAd-vancedAntennaSystem(AAS)RadioBaseStations.Astudyofeconomicallyviable, commerciallyavailablematerialsforconcealment,andmethodstodeter-mine theirdielectricpropertieswasdone.Apracticalinvestigationoftheeffectsome availableconcealmentmaterialsontheRFperformanceofthemm-Wavebase stationbeams,wasalsoperformed.Theresultsfromtheinvestigationsand measurementsperformedledtosomeusefulconclusionsandunderstand-ing aboutthevariousconcealmentmaterialsolutions.Overall,theinvestigatedconcealmentmaterialswerefoundtohavetwoprominenteffects:1. Reduction inEIRP(EquivalentIsotropicRadiatedPower)ofthebasestation beams(attenuation).2. Distortion intheshapeofthebasestationbeams.The boresightbeamsforalltheinvestigatedcaseswerefoundtobeattenu-ated(effect 1)bytheconcealments,butthesteeredbeamswerefoundtobebothattenuatedindistorted(effect2)bytheconcealments.Inparticular,con-cealmentswithathindielectricmaterialmeshstructurewerefoundtohavetheleast effectonthebasestationbeams.Allotherthicker(> 0=2), compositeconcealmentsandeventhosewithpurefoamstructures,werefoundtohaveanoticeable effectonthebasestationbeams.Inconclusion,thindielectricmesh,films andpaintscouldhencebeofinterestasconcealmentsolutionsforfurtherinvestigationsmovingforward.

  • 5.
    Bhowmik, Shreyasi
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.
    Investigation of Wide Band mm-Wave Radome2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    “Radome” is a necessary shield for any type of antenna. Itsshape, thickness, mechanical and electrical properties defineits application. This thesis mainly revolves around thetechniques, used for radome analysis in W-band with thehelp of electromagnetic solvers of High Frequency StructureSimulator (HFSS) and CST Microwave Studio. Measurementof permittivity of many materials is not made atsuch high frequencies and hence one is not sure about itsmaterial characteristics. This thesis includes a survey onmaterials which are applicable in W-band regime and givea sturdy performance with single type of material or commonlyknown as ‘Style A’ radomes. The thesis further describes,the shape and thickness modification of the radome.It contemplates on the the choice of solver involved and thedifferent advantages and disadvantages of the electromagneticsolvers with respect to this particular case. Severaltrials have been done on each of these platforms and onlythe relevant results have been presented. The antenna studiedis a “Travelling Wave Microstrip Patch Antenna” whichis subjected to different sizes of ground plane in order toobtain the realistic environment for it to be simulated in.It was observed that as the thickness of radome increased,the gain through the radome enclosed antennas decreasedbut the side lobe level performances improved. The simulationsdone in HFSS have a closer resemblance to theoryof radome performance.From the perspective of measurement, the return lossand insertion loss has been recorded for the radome in theW-band. A radome piece having different thicknesses hasalso been measured using the Rhode & Shwarz VNA. Asa step further, to study the radome pattern characteristic,Fabry perot periodic resonating dipoles are simulated ona radome of desired thickness. The height of the radomefrom the ground plane is optimized in order to get a 3-dB gain at the region of interest. After implementationit was observed that, around 76.5 GHz the setup which isdescribed later on acquired a gain of 20.33 dB. Althoughit is a high gain and low profile solution, it comes witha cost of narrow beam-width. Thus one has to optimizethe number of periodic elements along with phase taperingin order to achieve the desirable beam characteristics. Inshort, the thesis outlines the theory and thinking behinddesigning a radome, its effect on the antenna and how onecan resolve the issues.

  • 6.
    Björkqvist, Oskar
    KTH, School of Electrical Engineering and Computer Science (EECS).
    Analog Front End Development for the Large Hadron Collider Interlock Beam Position Monitor Upgrade2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The interlock Beam Position Monitor (BPM) system in the Large Hadron Collider(LHC) is responsible for monitoring the particle beam position at the point of thebeam dump kicker magnets and is part of the machine protection system. Thecurrent interlock BPM system has some limitations and because of this, an upgradeproject has been initiated. This master thesis describes the development of theanalog front end electronics of this system, consisting mainly of two parts: A delayline based microwave filter and a high isolation and highly balanced power combinercircuit.The filter has been validated with real LHC beam measurements and is found towork as expected. More work however needs to be done to ensure the effect that thefilter itself has on the beam measurements as the filter could introduce some ringingeffects on the signal. The highly balanced high isolation power combiner has beentested through lab measurements and also shows promising results but long-termtests need to be conducted to ensure the reliability of the component as it will needto endure very high signal levels over long periods of time.

  • 7.
    Bolmgren, Karl
    KTH, School of Electrical Engineering (EES), Space and Plasma Physics.
    Time dependence of average structure size and precipitation energy in pulsating aurora2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Pulsating aurora is low intensity aurora appearing in limited structures with quasiperiodicalmodulations in intensity. The highly energetic electron precipitation associatedwith pulsating aurora has been shown to cause chemical changes as far downas the mesosphere, causing ozone depletion. The drivers involved in generating pulsatingaurora are not fully known, and efforts have been made to model many of thesuggested mechanisms. In order to evaluate these results observational constraintson the temporal and spatial characteristics of pulsating aurora are necessary.Previous studies have noted that the pulsating area tends to decrease over timefrom studying single pulsating patches. This study examines a large set of all-skycamera data comprising approximately 400 image series with pulsating aurora fromthe MIRACLE network in northern Fennoscandia in order to determine the time dependenceof the average size and precipitation energy in pulsating aurora. The 20 stime resolution of the all-sky images makes it challenging to identify spatial boundariesof the pulsating structures whose periods have a typical range of 2-20 s. Twomethods are implemented here, with the same results showing a gradual decreasein average size. No relationship between UT and size is clear. The electron precipitationenergies are inferred from the peak emission height and 557,7 nm/427,8 nmintensity ratio, and seem not to be directly related pulsating structure size. Thepeak emission height shows a constant average energy following an initial increasefollowing the onset of the pulsating aurora, and the intensity ratio suggests a constantaverage electron precipitation energy.

  • 8.
    Bäckström, Hampus
    KTH, School of Electrical Engineering and Computer Science (EECS), Electromagnetic Engineering.
    Design and Evaluation of V/UHF Satellite Communication Antennas for Naval Applications2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In this master thesis, compact antenna design aimed towards naval applicationshave been designed, analyzed and evaluated. There is a recentinterest in the development of compact antennas to be used for smallersubmarine models, and with a smaller hull on a submarine, communicationand antenna systems must be adapted and minimized, which limitsantenna design. With two limiting cylindrical volumes with maximumallowed dimensions r = 10 cm, h = 50 cm and r = 5 cm, h = 90 cm,the antennas would operate on the upper to lower V/UHF band, radiatehemispherically and have a high RHCP purity. It was found that the mostappropriate antenna structure for both volumes was QHA design. Afterthe design and analysis process was completed, it was concluded that theshorter antenna design could meet all requirements set while the longerantenna design did not meet all requirements but could still establish agood communication link on the higher frequencies. Antenna prototypesbased on the produced design were constructed and measured and, despiteminor deviations, veried that the results obtained from this thesis werereliable.

  • 9.
    Conroy, Philip
    KTH, School of Electrical Engineering (EES), Space and Plasma Physics.
    Intradyne Signal Recovery and Equalization for Optical Satellite Links2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    An optical communication system employing intradyne reception withoffline digital signal processing for a geostationary satellite communicationscenario is presented. The digital signal processing is improvedvia the implementation and comparison of several timing recovery algorithms,and the inclusion of an equalization stage. The system istested over a 10.45 km link through the atmosphere, in which 40 Gbit/stransmission using binary phase shift keying in the optical C-band isdemonstrated. Results show that the system’s performance in the fieldclosely matches back-to-back measurements. Simultaneous channelmeasurements show that turbulence in the atmospheric channel representsa worst-case scenario for a geostationary satellite uplink.

  • 10.
    Dahlberg, Oskar
    KTH, School of Electrical Engineering and Computer Science (EECS), Electromagnetic Engineering.
    Low-dispersive Leaky-wave Antennas: A Viable Approach for Fifth Generation (5G) mmWave Base Station Antennas2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In this work, a method to achieve reduced beam-squint in fully metallic leaky-wave antennas is proposed and its applicability for high frequency, high gain, base station antennas in future communication networks is indicated.

    The antenna is built in gap waveguide technology, where the fundamental mode is allowed to leak by removal of one of the waveguide walls. The leakage is varied along the structure for reduced side lobes and a stable radiation pattern is obtained by coupling the leaked energy from the waveguide through a dispersive prism-lens.

    The gap waveguide is formed as a groove, sided by three rows of a glide-symmetric holey EBG-structure on one side, suppressing propagation of waves in that direction, and one row of vertical square pins, with tailored heights for optimal leakage, on the other. Beyond the single row of tailored pins, a prism-lens is placed. The prism lens is made of multiple rows of equally spaced and dimensioned, vertical square pins. The dispersive nature of the TE10-mode inside the waveguide is canceled by the oppositely dispersive prism-lens and a stable radiation beam (<1 degree beam-squint) is achieved over a 20% bandwidth.

    Two antennas are realized, both operating with a center frequency of roughly 60 GHz. The first design is optimized for single-beam operation such that the achieved efficiency is close to 90% across the band and the side lobe levels are below -20 dB. The second design is optimized for dual-beam operation such that two highly directive beams can be obtained, simultaneously or separately. The second design is placed in a 1D-array configuration for electrical beam-steering in one plane, and beam-switching in the orthogonal plane. The two antennas are simulated using CST Microwave Studio.

  • 11.
    Dickeli, Guillame
    KTH, School of Electrical Engineering (EES), Space and Plasma Physics.
    Statistical analysis of the electric field measurements from the Rosetta spacecraft in the plasma environment of comet 67P/Churyumov-Gerasimenko2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Comets are a key to understanding the early stages of the solar system. They were hereat its formation and have not evolved ever since, which means they are our best shotat learning the processes that led to the formation of the solar system as we know ittoday. Yet, our knowledge about these bodies is very limited. They are far from theEarth and small, which makes it complicated and expensive to reach them. But thestudy of the chemistry and geology of comets is not the only goal of the scientific community.The plasma environment of these astronomical bodies could also give answersto many questions regarding the science of plasma physics, such as the interaction ofthe solar wind with plasmas. Answering some of these questions was an objectiveof the Rosetta Mission. Before its launch, only three space missions out of eight targettingcomets had plasma instruments onboard. Rosetta carried several instrumentsdesigned to analyse the plasma environment of comet 67P/Churyumov-Gerasimenko.We were able to perform a statistical analysis of the electric field spectrum in the vicinityof comet 67P/Churyumov-Gerasimenko. This allowed us to determine two regionsof high spectral activity using the two probes of the LAP instrument and to proposeseveral theories about the physical processes that were active.

  • 12.
    Franzén, Fernando
    KTH, School of Electrical Engineering and Computer Science (EECS).
    Direction Finding: Determine the direction to a transmitter with randomly placed sensors2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    There are a lot of stand-alone and mobile platforms using transmitters today. Some want to be found while others do not. In our modern society there is a great demand of mobility and communication abilities. This means that several mobile platforms could potentially carry a sensor to record incoming signals to be used in Direction Finding.

    This thesis identifies the possibility to determine the direction to a transmitter with randomly placed sensors. By conducting a literature review well-known methods such as Time Difference Of Arrival (TDOA) and MUltiple SIgnal Classification (MUSIC) where chosen as methods in this analysis. The methods are applied on two antenna arrays, an Uniform Circular Array (UCA) and a Random Circular Array (RCA). The RCA is generated with randomly placed sensors. The performance in the Direction Of Arrival (DOA) is investigated in presence of time synchronization error and with different numbers of elements, radius and Signal to Noise Ratio (SNR). The ambiguity in the arrays is also investigated to insure a ambiguity-free DOA estimation.

    The results from this analysis identifies that the accuracy in the DOA estimation is dependent on the number of elements, SNR, the elements positions and the radius of the DF array. Furthermore, the accuracy of a UCA is greater than a RCA when the elements are randomly distributed within the area of a circle with radius R. Finally, it has shown that if time synchronization error occurs between the sensors, then the MUSIC method the accuracy will decrease greatly.

  • 13.
    Gurciullo, Antonio
    KTH, School of Electrical Engineering (EES), Space and Plasma Physics.
    Numerical study of spectral densities of fluctuations in thermal plasma2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    There are open issues within the uctuation theory owing to the approximations invoked

    in regimes outside fully ionized collisionless plasmas. This includes laboratory and space

    environments where e ects of Coulomb collisions or collisions with neutrals or dust particles

    cannot be ignored. Molecular Dynamics simulations have the potential to address

    such parameter regimes which are intractable by the analytical approach.

    The numerical method employed in this work for the calculation of the space-time correlation

    function of density uctuations is based on molecular dynamics in (r, v) space

    using an importance sampling Monte Carlo. The outcome of these MD simulation is

    then transformed into Fourier space to enable comparison with the analytical results of

    the uctuation theory. The comparison is carried out in the regime of thermal collisionless

    fully ionized plasmas, with no drifts and neutral component, in order to verify the

    numerical approach, choose appropriate simulation and FFT settings and to estimate

    error bars on the features of the electron spectral density of uctuations.

  • 14.
    Hasan, Mohammad
    KTH, School of Electrical Engineering (EES), Space and Plasma Physics.
    Modeling the extraction of sputtered species out of a pulsed hollow cathode2011Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
  • 15.
    Hussain, Nizamudin
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.
    Nizamudin Hussain, Performance Limitations and Estimates for Infinite Array Antennas2013Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    A novel quantitative measure for predicting the performance of arrays is tested on a few selected wide band arrays. This measure is called the array figure of merit. It is valid for lin-early polarized, infinite planar arrays, which are backed by a perfectly conducting ground plane. It predicts performance of arrays (which are free from grating lobes) in the E- or H-plane. The array figure of merit builds on the low frequency asymptotic expansion of the reflection coefficient and a sumrule of Rozanov type for passive structures. This measuretakes values between zero and one, and estimates array's performance on the basis of four key trade-off parameters:return loss, scan range, array thickness, and bandwidth. Arrays were found that yield values as high as 0.67, thus indicating a high performance array with respect to this measure. The sensitivity of the array figure of merit with respectto scan range is studied. Trade-off between bandwidth andreflection coefficient is investigated with respect to the ar-ray figure of merit. Finally an infinite array of stronglycoupled dipole elements is modeled and simulated. For this array, we test the sum rule based measure and find a veryhigh value for this measure: 0.84 - with 1 as its theoretical upper limit. This measurement reveals some insight into the influence of approximating material properties on the antenna performance measure.

  • 16.
    Ivan, Ionut Madalin
    KTH, School of Electrical Engineering (EES), Space and Plasma Physics.
    Analysis of the electric and magnetic fields time variation inside the auroral oval region2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The Master's thesis is part of a more comprehensive research topic aimed at investigating

    the interaction between the magnetosphere and the ionosphere. The study of the

    temporal variation of the eld aligned currents in the auroral region was done through

    analyzing Electric and Magnetic eld data downloaded from the ESA Cluster Active

    Archive and gathered through in situ measurements by the tetrahedral Cluster satellite

    constellation. The four satellites have an almost identical orbit, with a distance separation

    ranging between a hundred kilometers to several thousand kilometers. This allows

    for the measurement of the Electric and Magnetic elds associated with Birkeland currents

    in the same spatial region at four dierent times. By performing a cross-correlation

    between any two spacecraft measurements we obtain six correlation coecients along

    with the corresponding time lags, which can then be used to study the lifetime of the

    associated eld aligned currents. Further data analysis and interpretation is then performed

    to obtain a better understanding of the temporal stability of auroral structures

    and the intrinsic coupling between the ionosphere and the magnetosphere.

  • 17.
    Kambisseri Roby, Neelu
    KTH, School of Electrical Engineering and Computer Science (EECS).
    Wireless communication using metasurfaces for condition monitoring in motor2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Wireless sensors are used widely for condition monitoring in electric machines. The metal enclosure of an electric motor restricts the signal from sensors to radiate outside. The signal from the metal cavity needs to be guided to the only opening in the enclosure, through a narrow gap between the stator and the rotating rotor.

    Gap waveguide technology is proposed as a solution by texturing the stator surface with electromagnetic band gap (EBG) structures. Arrays of periodic holey structures are used to realize the metasurface waveguide. Two Bravais lattice structures – square and hexagonal, are explored for guiding waves along a desired path in a parallel plate waveguide. Simulations are carried out to study the influence of various dimensions of the unit cells. A waveguide with hexagonal hole-type unitcell is designed and manufactured for experimental verification. The possibility of extending the same technology to cylindrical surface is confirmed by simulations.

  • 18.
    Kazemi, Noj
    KTH, School of Electrical Engineering and Computer Science (EECS), Electromagnetic Engineering.
    Circuit analysis of a parallel plate waveguide2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The aim of this work was to model a four-port waveguide as a simple circuit,by first starting with a two-port then a three-port waveguide. Duethat the work was based on Nathan Marcuvitz book Waveguide handbook,an analytical solution for the circuit parameters was desired. In order toobtain an analytical solution three methods were studied; the Variationalmethod, the Integral equation method and the Static method. Out of thesethree methods the latter was chosen, because its strength of simplifying theboundary conditions. The goal to model a four-port and a three-portedwaveguide was too complicated. This led to that the goal was changed totrying to get a higher accuracy on the existing circuit model for a two-portwaveguide, by solving an extension to the circuit parameter. This was donebecause Marcuvitz only treated the first two modes correctly and it was notclear if the circuit model was stable for the higher orders of Taylor series. Inthe end a circuit model for a waveguide with an iris that treats the first 16modes correctly was solved. By looking at the dispersive properties of thecircuit a comparison with simulation software CST Microwave Studio couldbe done, which resulted in that the circuit model gave good results up to2b/ < 1. It was also showed that the accuracy was about the same as thecircuit model found in Waveguide handbook, but it can be mentioned thatthe accuracy is minimally better for the circuit model that was developed inthis work. Something that was discovered in this work is that the restrictionmentioned in Waveguide handbook for the case when the window is centeredis unreliable, it should be 2b/ < 1. It also appeared that the circuit modelremained stable for higher orders of the Taylor series, in this case up to the16:th order.

  • 19.
    Lai, Ying-Chun
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.
    A Development of a Common-Mode FilterUsing an EBG Structure in High Speed SerialLinks2012Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    As signal speed increases and electronic products become progressively smaller,the risks of electromagnetic radiation and interference are also heightened.Ericsson's SCXB, an Ethernet switch card, experiences exactly this problem,with excessive emission levels probably caused by common-mode noise.In this project, a common-mode lter using the electromagnetic bandgap(EBG) structure has been designed and implemented in the SCXB. Unlikeconventional common-mode lters, the common-mode lter is embedded inthe printed circuit board (PCB) beneath the dierential lines. The eect ofthe common-mode lter is assessed by measuring the insertion loss and thepower radiation of a shielded cable connected to the common-mode lter.A compact common-mode lter using an EBG structure has been proposedin this project and this works eectively at 937.5 MHz. One of the resultsfrom the parametric analysis shows that the common-mode lter is suitableto work in a high frequency range due to the smaller structure and the widerbandwidth range. The common-mode lter is constructed with the PCBfabrication process. No additional components are necessary, although morelayers of the PCB's stack up are required in which to embed the common-mode lter.

  • 20.
    Lindberg, Martin
    KTH, School of Electrical Engineering and Computer Science (EECS), Electromagnetic Engineering.
    Mode Matching Analysis of One-Dimensional Periodic Structures2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In this thesis, we analyze the electromagnetic wave propagation in waveguidestructuresexhibiting periodical geometry, including glide symmetry. The analysisis performed using a mode matching technique which correlates the different modecoefficients from separate but, connected regions in the structure. This technique isused to obtain the dispersion diagrams for two one-dimensional periodic structures:a glide-symmetric corrugated metasurface and a coaxial line loaded with periodicholes. The mode matching formulation is presented in Cartesian and cylindricalcoordinate system for the former and the later, respectively. The mode matchingresults are compared to simulated results obtained from the Eigenmode Solver inCST Microwave Studio and are found to agree very well.

  • 21.
    Ljungberg, Björn
    KTH, School of Electrical Engineering and Computer Science (EECS).
    3D Finite Element Modelling of ICRH in JET2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This master's thesis assesses the possibility of using the nite element method to solve the electromagneticwave equation in a fusion plasma in 3D. In particular, the frequency is chosen to match that of ioncyclotron resonance heating in the fusion experiment JET. In this work, a brief introduction on fusion isgiven, followed by an explanation of the damping process in a plasma. A projection of the 3D wave eldonto a poloidal plane is compared to the 2D wave eld produced by the code FEMIC for validation ofthe developed 3D code. The comparison was done with good results.The power spectrum and coupling resistance per toroidal mode obtained from the 3D model arealso compared to the corresponding quantities obtained from an analytical slab model. Though somediscrepancies can be seen near the toroidal mode number n = 0 and for higher mode numbers (jnj > 70),the appearance of the power spectra are similar. The dierence near n = 0 is attributed to inducedcurrents in the reactor wall, whereas for higher mode numbers, the dierence is likely due to bad resolution.The induced currents in the wall causes singularities in the chosen model of the coupling resistance. Thisproduces unreliable predictions of the coupling resistance.

  • 22.
    Lycken, Tomas
    KTH, School of Electrical Engineering (EES), Fusion Plasma Physics.
    Modelling of Collisionless Alpha-particle Confinement in Tokamaks2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    A collisionless model for fast-ion transport in a tokamak

    reactor is derived from first principles, and a new orbitfollowing

    code is developed to simulate this model. Results

    from the model applied on two scenarios of DT fusion

    plasmas, one from ITER and one from JET, are compared,

    and the prompt losses as well as the effects of orbit

    shapes are quantified; it is shown that both the prompt

    losses and the orbit effect on confined particles are very

    small in both reactors. Although some problems are still

    present, the method presented shows potential for further

    investigating orbit effects.

  • 23.
    Magnusson, Patrick
    KTH, School of Electrical Engineering (EES), Space and Plasma Physics.
    Antenna for GNSS Reception in GEO-Orbit2014Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    There are a number of global navigation satellite systems (GNSS), in use or planed,

    which are used for navigation on earth but also for autonomous navigation of satellites

    in low earth orbit (LEO). It would be desirable to also have autonomous navigation in

    geosynchronous earth orbit (GEO) to reduce costs and make it possible to get higher

    accuracy on the position of the satellite. One part of the navigation system is the

    GNSS antenna which is examined in this master thesis.

    The specifications of the antenna were first decided and then three antenna

    alternatives were investigated in greater detail: a monofilar helix antenna, a three

    element circular array antenna and a twelve element circular array antenna. The result

    was that they would all work as a GNSS antenna in GEO but none could be judged to

    be the best under all circumstances. The size requirement for the mission and the used

    GNSS receiver would primarily decide which fits the mission best.

  • 24.
    Masselin, Matthieu
    KTH, School of Electrical Engineering (EES), Space and Plasma Physics.
    Development of a hybrid PIC code for the simulation of plasma spacecraft interactions2012Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Electric propulsion is gaining popularity in space industry. This type of propulsion is replacing chemical propulsion for different maneuvers. But it deeply modifies the ambient plasma that surrounds the satellites and can affect the operation of satellites. Modelling the interactions arising from electric propulsion is then critical. In the frame of SPIS, a simulation software designed to simulate plasma-spacecraft interactions, European Space Agency (ESA) started the AISEPS project which aimed at modelling these interactions. Here, we report the development of new features for SPIS during the last phase of the AISEPS project, how they operate and were tested. Using these developments, a complete spacecraft is modelled and the variation of its floating potential resulting from its solar array rotation is reproduced.

  • 25.
    Miao, Jingwei
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.
    Ka-band 2D Luneburg Lens Design with Glide-symmetric Metasurface2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    A Luneburg lens is a beam former that has two focal points where one isat the surface and the other lies at innity. It is a cheap passive steerableantenna at high frequencies. In this thesis, a 2D at-prole Luneburglens with all-metal structure is designed for Ka band. Commercial softwareCST Microwave Studio Suite and Ansys Electronic Desktop (HFSS)are used for simulations.The lens is composed of two glide-symmetric metasurface layers with asmall gap in between. The high order symmetry, glide symmetry, couldprovide ultra wide band property for the lens. Each layer contains manyunit cells. Dierent unit cells are tested in this thesis to nd the best solutiontaking into account both electromagnetic properties and the easinessof manufacturing. A are is designed to achieve better matching betweenthe air gap of the lens and free space. A self-designed waveguide feedingis also used, including a transition from coaxial cable to TE10 mode ofrectangular waveguide at the focus of the lens.The prototype will be built in the future and measurements will be doneto compare with simulation results in this thesis.

  • 26.
    Neuner, Oliver
    KTH, School of Electrical Engineering (EES), Communication Networks.
    Automatic learning of state machines for fault detection systems in discrete event based distributed systems2011Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The electronic components in modern automobiles build up a distributed system with so called electronic control units connected via bus systems. As more safety- and security-relevant functions are implemented in such systems, the more important fault detection becomes. A promising approach to fault detection is to build a system model from state machines and compare its predictions with properties observed in a real system. In the automobile, potential are communication characteristics between the distributed control units. Especially, the sequence of transmitted messages can be used as the basis for supervising the communication. This thesis investigates if data gathered during system tests can be used to create state-machine system models. Such an automatically created model reflects the observed normal system behavior and can potentially be used for fault detection purposes. The task can be seen as learning a state machine from a single long message sequence. Today’s automata learning algorithms are not designed for such singlemessage- sequence input data. Especially, learning without interaction between the original system and the learning algorithm is in general a NPcomplete task. Additionally, if only positive data from the normal behaving system is available, the task is further complicated. The well-known Angluin’s L∗ state-machine learning algorithm works in general independent from the type of input data. In order for this algorithm to be applicable, certain queries have to be answered. This work proposes a statistical approach to answer such queries. The implemented adapted Angluin algorithm showed the potential of automatic model building in fault detection systems and, in particular, the possibility of learning state machines from a single positive data stream.

  • 27.
    Prasad Sishtla, Chaitanya
    KTH, School of Electrical Engineering and Computer Science (EECS).
    A kinetic perspective of electron trapping near a weakly outgassing comet2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The European Space Agency’s Rosetta spacecraft followed the comet 67P/Churyumov-Gerasimenko from August 2014 to September 2016, providingobservations of the comet ionosphere at varying heliocentric distances. Measurementsfrom the Rosetta mission have shown a multitude of non-thermalelectron distributions in the cometary environment, challenging the previouslyassumed origin and plasma interaction mechanisms near a cometary nucleus.In this thesis, we discuss electron trapping near a weakly outgassing cometfrom a fully kinetic (particle-in-cell) perspective which self consistently describethe ambipolar field. Using electromagnetic fields derived from the simulation,we characterize the trajectories of trapped electrons in the potentialwell surrounding the cometary nucleus and identify the distinguishing featuresin their respective velocity and pitch angle distributions. In accordancewith theoretical findings in space plasma, our analysis allows us to define aclear boundary in velocity phase space between the distributions of trappedand passing electrons.

  • 28.
    Sjöström, Daniel
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Unlicensed and licensed low-power wide area networks: Exploring the candidates for massive IoT2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In the Internet of things (IoT), many applications will require low-power and low-cost to achieve long lifetime and scale (respectively). These types of applications are referred to as massive IoT, as opposed to critical IoT, which emphasizes ultra-high reliability and availability and low latency. One type of network catering to massive IoT applications are Low-Power Wide Area Networks (LPWANs), and presently, many LPWAN standards are trying to assert their role in the IoT ecosystem.

    This thesis explores LPWANs from both technical and non-technical perspectives to ascertain their use-case versatility and influence on the future telecommunications’ landscape. With respect to spectrum, the studied LPWANs may be categorized as unlicensed LPWAN or licensed LPWAN. The prior category typically refers to proprietary solutions and in this thesis are represented by SigFox and LoRaWAN. The latter group includes EC-GSM-IoT, eMTC, and NB-IoT and can be considered synonymous with cellular LPWAN because they are designed to be integrated into existing cellular infrastructures.

    The results indicate that all of the different types of explored LPWANs support applications without strict downlink, payload size, and latency requirements. For use cases without these specific demands (typically sensors, meters, tracking, etc.), it is not a question of whether or not a network fulfills the requirements, but rather how flexible the requirements are. As a result the choice of network will be determined by non-technical aspects and a cost versus functionality trade-off where unlicensed LPWAN is typically cheaper. Hence, both categories of LPWANs offer a unique value proposition; therefore, they can be considered complementary. This notion is reinforced when looking at non-technical aspects such as ecosystem, regulation, network ownership and control, and network coordination, which differ quite significantly. Furthermore, unlicensed LPWANs are likely to be the vanguard of a new type of competitor offering the core service of connectivity.

  • 29.
    Stanev, Asparuh
    KTH, School of Electrical Engineering (EES), Space and Plasma Physics.
    Experimental studies of nucleation and growth of nanoparticles using a pulsed hollow cathode discharge2011Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The properties of the nanoparticles are highly eected by their size. In order to apply nanoparticles commercially it is desirable to synthesize them with a narrow size distribution and at high productivity. We synthesized copper nanoparticles (grains) using a plasma generated by a hollow cathode with a pulsed voltage. The gas used for sputtering was argon. The collected copper grains were analyzed by scanning electron microscopy and afterwards their size distribution was analyzed. We studied the inuence on the size distribution of four parameters: mesh; magnetic eld (B- eld); anode ring position; frequency. The productivity of the setup was highly inuenced by the mesh. No grains were found on the substrates after experiments run without both the B- eld and the mesh. The productivity was also dependent on the B- eld. We noticed that when the B- eld was applied to a no-mesh setup we collected a few grains. The size of the grains was eected by the position of the anode ring and the value of the frequency. The size of the grains enlarged when the distance between the hollow cathode and anode ring was increased. The eect of grains enlargement was also seen with increasing frequency.

  • 30.
    Tolias, Panagiotis
    KTH, School of Electrical Engineering (EES), Space and Plasma Physics.
    Kinetic effects in low-temperature responses of dusty plasmas2010Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
  • 31.
    Tourtier, alice
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Satellite Positioning.
    Study of the contribution of an ionospheric model embedded on a dual frequency GNSS receiver.2016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    GNSS (Global Navigation Satellite System) is a system that allows a receiver to know its position. It includes GPS (Global Positioning System), a system designed by the United States, Galileo (European), Beidou (Chinese) and others.Currently, with a stand-alone GPS receiver, the accuracy on the position estimation is around 1m. Indeed,GNSS signals are altered when spreading through the atmosphere and can be diffracted, reflected or scattered by the nearby environment of the receptor. These contributions (respectively called atmospheric delay and multipath) lead to errors on the receiver position estimation. The goal of this study is to present methods in order to tackle these errors.

  • 32.
    Tuoriniemi, Teemu
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.
    Automotive Power Line Communication: A New Wiring Topology for Powertrain Sensor Network: A pre-study on the technical feasibility of implementing power line communication for Volvo powertrain sensor network2013Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In motor vehicles the power and information are distributed by their own separate wiresand the amount of wires over the past decades has increased tremendously due to theever increasing electronics onboard. Solely the average weight of the wires has increasedfrom 4 to 91 kg over the last 50 years and it is therefore clear that a remedy to theever increasing wiring is needed. A possible solution to this could be to introducepower line communication (PLC) onboard a vehicle. The PLC aims at overlaying theinformation on top of the already existing power feed cables and thus eliminating theneed of dedicated wires for communication purposes. The PLC solution would thussimplify the wiring network to a bare minimum, since no additional wires besides thepower cables are needed.During this thesis work the PLC technology was studied as a possible cost and qualityreform of the powertrain sensor network, where it could be used to both reduce the costof wires and increase the system reliability.A theoretical background study was rst performed to investigate the limitations andpossibilities of the PLC implemented in a vehicle, and the PLC technology was alsotested upon the DC-lines of an e6 Volvo FMX truck, between the post catalytic NOxsensor and the ACM with two CAN protocol based PLC modems. The throughput, noiseand the scalar voltage gain was measured in this link with the ignition key at dierentpositions to test dierent modes of operations. It was shown that this particular link hada clear low pass characteristics with severe voltage attenuation without any signicantdierence caused by the dierent modes of operation. The severe characteristics of thelink did result into a fault connement mode of the CAN based PLC modems wheretheir communication capabilities were inhibited, which shows that at least with thisparticular link, reliable communication was not possible with the equipment at hand.Short EMC measurements were also carried out regarding the radiated emissions. Theresults showed that the PLC technology implemented in the existing wiring architecturecould be a possible cause of EMC problems if no counter actions are been taken intoaccount.Some of the economical aspects were also investigated, but most of the results were leftas hypothetical assumptions. A detailed cost saving analysis was nevertheless made onthe EATS-wire harness where the savings were estimated to be 1e. It is the hope thatthese calculations could be used as a sounding board for future PLC wire harness costanalysis.

  • 33.
    Vencels, Juris
    KTH, School of Electrical Engineering (EES), Space and Plasma Physics.
    The Hermite-Fourier spectral method for solving the Vlasov-Maxwell system of equations2016Independent thesis Advanced level (degree of Master (Two Years)), 80 credits / 120 HE creditsStudent thesis
    Abstract [en]

    This thesis focuses on the improvement of the Hermite-Fourier spectral method for solving kinetic plasma problems. In the first part of the thesis a novel dynamically adaptive techniques for changing the number of Hermite modes and Hermite basis are presented. Preconditioning of the problem and use of high-end scientific toolkit PETSc are discussed. The technique of changing the number of modes and preconditioning are believed to reduce computational time, while a change of basis improves robustness and numerical convergence of the method. The second part of the thesis focuses on paralellization strategies and performance analysis of the code implemented in the Fortran programming language.

  • 34.
    Zaheer, Muhammad
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Geoinformatics.
    Kinematic orbit determination of low Earth orbiting satellites, using satellite-to-satellite tracking data and comparison of results with different propagators2014Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The GPS data from Challenging Mini-satellite Payload (CHAMP) is used for its orbit determination for the epoch day of January 1st 2002.  The orbit of CHAMP is computed from the GPS data and ionospheric effects are removed by frequency combination.

    Further, the orbits of CHAMP for the same epoch day are computed using the satellite tool kit (STK) employing simplified general perturbations (SGP4) and a high precision orbit propagator (HPOP). Results from both techniques (GPS computed orbit and STK computed orbit) are compared.

    Furthermore, orbits computed using GPS data are also compared with jet propulsion laboratory’s published CHAMP spacecraft orbit and we have found that root mean square difference in ECEF position X component is below 0.01km other than some spikes at poles. The standard deviation of the difference in ECEF position X coordinate is 11.7m.

    The accuracy of our computed satellite positions (using GPS data) is about 12 metres for other than polar areas. However there are some occasional spikes, especially at poles, having maximum errors (about 0.055 km).

  • 35.
    Zaheer, Muhammad
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Geoinformatics.
    Kinematic orbit determination of low Earth orbiting satellites, using satellite-to-satellite tracking data and comparison of results with different propagators2014Independent thesis Advanced level (degree of Master (Two Years)), 80 credits / 120 HE creditsStudent thesis
    Abstract [en]

    GPS data from Challenging Mini-satellite Payload (CHAMP) is used for its orbit determination for the epoch day of January 1st 2002.  The orbit of CHAMP is computed from the GPS data and ionospheric effects are removed by frequency combination.

    Further, the orbits of CHAMP for the same epoch day are computed using the satellite tool kit (STK) employing simplified general perturbations (SGP4) and a high precision orbit propagator (HPOP).

    Furthermore, orbits computed using GPS data are also compared with jet propulsion laboratory’s published CHAMP spacecraft orbit and we have found that root mean square difference in ECEF position X component is below 0.01km other than some spikes at poles. The standard deviation of the difference in ECEF position X coordinate (JPL results – GPS computed results) is 11.7m. Since JPL computed orbits are considered as true orbits of CHAMP with accuracy of centimeter level (https://gipsy-oasis.jpl.nasa.gov/). Therefore this difference can also be referred as observed error in GPS computed orbits. Considering above discussion, we can expect that accuracy of our computed satellite positions (using GPS data) is about 12 metres for other than poles area. However there are some occasional spikes, especially at poles, having maximum errors (about 0.055 km).

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