Dissertations / Theses on the topic 'Vector network analyzer (VNA)'

The VSWR is an important entity when assessing the properties of an antenna. This report presents measurements of the VSWR, related to antennas, by means of a Vector Network Analyzer. The open/short/load calibration method is used as a preparation before the actual measurement in order to obtain accurate results. The way that the VSWR depends on frequency is illustrated by three measurment methods: direct measurement of the VSWR, by using 𝑆11, or by using the Smith chart. The results are compared and conclusions are drawn.

In the present work, the implications of ion irradiation on the magnetostatic and dynamic properties of soft magnetic Py/Ta (Py = Permalloy: Ni80Fe20) single and multilayer films have been investigated with the main objective of finding a way to determine their saturation magnetization. Both polar magneto-optical Kerr effect (MOKE) and vector network analyzer ferromagnetic resonance (VNA-FMR) measurements have proven to be suitable methods to determine µ0MS, circumventing the problem of the unknown effective magnetic volume that causes conventional techniques such as SQUID or VSM to fail. Provided there is no perpendicular anisotropy contribution in the samples, the saturation magnetization can be determined even in the case of strong interfacial mixing due to an inherently high number of Py/Ta interfaces and/or ion irradiation with high fluences. Another integral part of this work has been to construct a VNA-FMR spectrometer capable of performing both azimuthal and polar angle-dependent measurements using a magnet strong enough to saturate samples containing iron. Starting from scratch, this comprised numerous steps such as developing a suitable coplanar waveguide design, and writing the control, evaluation, and fitting software. With both increasing ion fluence and number of Py/Ta interfaces, a decrease of saturation magnetization has been observed. In the case of the 10×Py samples, an immediate decrease of µ0MS already sets in at small ion fluences. However, for the 1×Py and 5×Py samples, the saturation magnetization remains constant up to a certain ion fluence, but then starts to rapidly decrease. Ne ion irradiation causes a mixing and broadening of the interfaces. Thus, the Py/Ta stacks undergo a transition from being polycrystalline to amorphous at a critical fluence depending on the number of interfaces. The saturation magnetization is found to vanish at a Ta concentration of about 10–15 at.% in the Py layers. The samples possess a small uniaxial anisotropy, which remains virtually unaffected by the ion fluence, but slightly reduces with an increasing number of Py/Ta interfaces. In addition to magnetostatics, the dynamic properties of the samples have been investigated as well. The Gilbert damping parameter α increases with both increasing number of Py/Ta interfaces and higher ion fluences, with the former having a stronger influence. The inhomogeneous linewidth broadening ΔB0 increases as well with increasing number of Py/Ta interfaces, but slightly decreases for higher ion fluences
In dieser Dissertation ist der Einfluss von Ionenbestrahlung auf die magnetostatischen und dynamischen Eigenschaften von weichmagnetischen Py/Ta-Einzel- und Multilagen (Py = Permalloy: Ni80Fe20) untersucht worden, wobei das Hauptziel gewesen ist, eine Methode zur Bestimmung der Sättigungsmagnetisierung zu finden. Sowohl polare magneto-optische Kerr-Effektmessungen (MOKE) als auch ferromagnetische Resonanzmessungen mittels eines Vektornetzwerkanalysators (VNA-FMR) haben sich als geeignet erwiesen, um µ0MS zu bestimmen, wobei das Problem des unbekannten effektiven magnetischen Volumens umgangen wird, welches bei der Verwendung von Techniken wie SQUID oder VSM auftreten würde. Unter der Voraussetzung, dass die Proben keinen senkrechten magnetischen Anisotropiebeitrag besitzen, kann die Sättigungsmagnetisierung selbst im Fall starker Grenzflächendurchmischung infolge einer großen Anzahl an Py/Ta-Grenzflächen und/oder Ionenbestrahlung mit hohen Fluenzen bestimmt werden. Ein weiterer wesentlicher Bestandteil dieser Arbeit ist die Konstruktion eines VNA-FMR-Spektrometers gewesen, welches vollautomatisiert ist, polare und azimutale Winkelabhängigkeiten messen kann und einen Magneten besitzt, der Proben, die Eisen beinhalten, sättigen kann. Von Grund auf beginnend umfasste dies zahlreiche Schritte wie z. B. die Entwicklung eines geeigneten koplanaren Wellenleiterdesigns sowie das Schreiben von Steuerungs-, Auswertungs- und Fitprogrammen. Mit steigender Fluenz und Zahl an Py/Ta-Grenzflächen ist eine Abnahme der Sättigungsmagnetisierung beobachtet worden. Im Fall der 10×Py-Proben findet diese bereits bei kleinen Fluenzen statt. Im Gegensatz dazu bleibt µ0MS der 1×Py- und 5×Py-Proben bis zu einer bestimmten Fluenz konstant, bevor sie sich dann umso schneller verringert. Die Bestrahlung mit Ne-Ionen verursacht eine Durchmischung und Verbreiterung der Grenzflächen. Infolgedessen erfahren die Py/Ta-Proben bei einer kritischen Fluenz, die von der Zahl der Grenzflächen abhängig ist, einen Phasenübergang von polykristallin zu amorph. Die Sättigungsmagnetisierung verschwindet ab einer Ta-Konzentration von etwa 10–15 Atom-% in den Py-Schichten. Die Proben besitzen eine kleine uniaxiale Anisotropie, die praktisch unbeeinflusst von der Fluenz ist, sich jedoch mit steigender Zahl an Py/Ta-Grenzflächen leicht verringert. Neben den statischen sind auch die dynamischen magnetischen Eigenschaften der Proben untersucht worden. Der Gilbert-Dämpfungsparameter α erhöht sich sowohl mit steigender Zahl an Py/Ta-Grenzflächen als auch mit höheren Fluenzen, wobei Erstere einen größeren Einfluss hat. Die inhomogene Linienverbreiterung ΔB0 nimmt ebenfalls mit steigender Zahl an Py/Ta-Grenzflächen zu, verringert sich jedoch bei größeren Fluenzen leicht

A greater understanding of precessional dynamics in magnetic systems is central to several emerging technologies. This thesis presents the design, construction and development of a Vector Network Analyser based Ferromagnetic Resonance measurement instrument (VNA-FMR), and its application in characterising dynamic material properties in hybrid anisotropy [CoPd]8-NiFe films, produced by remote plasma sputtering. Potential applications for hybrid films include Spin Torque Oscillators (STOs) or Vortex Oscillators (VO) for use as microwave emitters in, for example in Microwave Assisted Magnetic Recording (MAMR). The VNA-FMR system was first used to measure thin films of NiFe (permalloy) which allowed its capabilities to be quantified and compared to systems reported in the literature. The instrument demonstrated the capability of measuring permalloy films down to a thickness of 3 nm and was used to measure resonance and damping behaviour which agreed well with theory. The results obtained forMs were in agreement with measurement using Vibrating Sample Magnetometry. The effect of interlayer exchange on FMR was explored in hybrid films using a sample series with varying Pd spacer layer thickness, t, [Co/Pd]-Pd(t)-NiFe. As Pd spacer thickness increased, a transition was observed from near complete coupling with a single resonance mode to separate acoustic and optical branches of resonance. As spacing was further increased, the branches converged towards the resonances of the individual component layers of the hybrid films. The results suggest exchange coupling has a range of less than 2 nm, and is completely extinguished at 5 nm, in agreement with previous measurements. However, a change in damping behaviour was observed between 10 and 20 nm spacer thickness, independent of field orientation.

La caractérisation des composants hyperfréquences après leur fabrication, est généralement réalisée par la mesure de paramètres S à l’aide d’un analyseur vectoriel de réseau (VNA). La précision de mesure dépend étroitement de la qualité du calibrage de l’analyseur vectoriel, qui permet de corriger les erreurs inhérentes au système de mesure. Des composants particuliers, dits étalons ou standards, dont les paramètres sont complètement ou partiellement connus, sont mesurés lors de la procédure de calibrage afin de déterminer les erreurs systématiques du système. La réalisation d’un circulateur coplanaire (les trois ports sont à 120 degrés les uns des autres) travaillant autour de 40 GHz est l’un des axes de recherche du laboratoire depuis plusieurs années et la caractérisation des prototypes a toujours été un souci important. Le calibrage est réalisé avec un kit commercial, avec les pointes positionnées en face à face. La mesure des dispositifs CPW à accès orthogonaux ou obliques après un calibrage avec un ensemble de standards conventionnels (droits) peut engendrer des erreurs supplémentaires. L’objectif de notre travail est donc de concevoir un ensemble de standards à accès inclinés à 120 degrés permettant de calibrer l’analyseur vectoriel « 2-ports » en positionnant directement les pointes à 120 degrés. La méthode de calibrage TRL (THRU – REFLECT - LINE) a été choisie. Le travail à accomplir se résume comme suit : - faire une étude de simulation du nouveau kit de calibrage à concevoir ; - mettre en évidence l’effet des accès coudés sur les lignes de transmission des standards ; - proposer une méthode de calcul qui tient compte de ces effets lors de la procédure de calibrage ; - mesurer quelques échantillons réalisés afin de vérifier la validité de la procédure de calibrage proposée. Les résultats obtenus au cours de ce travail ont pu être validés expérimentalement et offrent de nouvelles perspectives pour la mesure des composants planaires à accès non conventionnels
Microwave components characterization after the fabrication steps is usually performed by measuring S parameters using a Vector Network Analyzer (VNA). The measurement accuracy is highly dependent on the quality of the VNA calibration, which corrects the inherent errors in the measurement system. Specific components, called standards and whose parameters are completely or partially known, are measured during the calibration procedure to determine systematic errors of the system. Fabricating a coplanar circulator (the three ports are at 120 degrees position) functioning around 40 GHz is one of the laboratory’s research areas for several years and characterization of prototypes has always been a major concern. Usually, the calibration is made with a commercial kit ; probes are in face-to-face position. Measurements of CPW devices with orthogonal or bended accesses (120 degrees in our case) after VNA calibration with conventional (straight) set of standards may generate additional errors. The aim of our work is to design a set of standards with 120_ bended accesses allowing the calibration of the “2-ports” network analyzer. Therefore, probes are directly set at 120_ position. TRL (THRU - REFLECT -LINE) calibration procedure is chosen for the standards design. The work to be done is as follows : - to make a simulation study of the new calibration kit to design ; - to determine the bended accesses effects on the standards transmission lines ; - to propose a calculation method that takes account of these effects during the calibration procedure ; - to measure some fabricated samples to verify the validity of the proposed calibration procedure. The results of this research work have been experimentally validated and offer new perspectives for measuring planar components with unconventional accesses

The objective of this thesis work was to implement all the hardware and software necessary to simulate the functionality of a Vector Network Analyzer (VNA). With equipment that is already available, and is common in a measurement station, the most common functions of a VNA were implemented, using an Vector Signal Generator, that provide the signal for testing, and a Vector Signal Analyzer, to make all the amplitude and phase measurements. With these instruments and the appropriate software that control them, the basic functionality of a Vector Network Analyzer can be achieved with a reasonable accuracy. With this system, we can reduce costs, avoiding the need of a real VNA and take advantage off instruments that are already available in a laboratory. A Complete measurement system of all four scattering parameters is proposed at the end of the report for future implementation. With this implementation all the different S-parameter measurements were made with an acceptable accuracy that can be comparable to a commercial VNA.

Noise contribution in nonlinear systems is very different from that in linear systems. The noise effects in nonlinear systems can be complicated and not obvious to predict. In this thesis, the focus was on the noise contribution in nonlinear systems when measuring with the nonlinear vector network analyzer (NVNA). An additional noise source together with a single sinewave signal was fed into the input of the amplifier and the performance was studied. The input power of the amplifier is considered to be the sum of the noise power and the signal power. The variation of the 1 dB compression point and the third order interception point as functions of the added noise power were studied. From the measured results in this thesis, the 1 dB compression point referred to the output power will decrease when increasing the added noise power at the input of the amplifier. The contribution of the added noise to the 1 dB compression point of an amplifier is considered dual: with the added noise the linear regression lines of the AM/AM curves are changed, and due to hard clipping the useful output power is reduced. As a result of those two effects, the added noise made the compression start at a lower power level. When the added noise reaches a certain level, the 1 dB compression point is hard to measure. Thus when performing nonlinear measurements, the noise effects should be taken into considerations and further studies are required to get better understanding of the system’s behavior in noisy environment.

Объектом исследования является прибор DIY Vector Network Analyzer UVNA-63. Целью работы является разработка программного обеспечения для DIY Vector Network Analyzer UVNA-63. В данной работе описана разработка программного обеспечения в программе Matlab. Описана работа разработанных функций измерения. Описана работы разработанного графического интерфейса. Доработка методики лабораторных работ. Актуальность работы обоснована отсутствием программного обеспечения для проведения измерений на векторном анализаторе цепей, который имеется в распоряжении кафедры и может быть задействован в учебном процессе. Разработанное ПО позволит проводить измерения, производить калибровку аппарата, сохранять полученные данные в различных форматах, отображать полученные данные на графике и устанавливать маркеры на графике. Область применения является учебная сфера. С помощью разработанного программного обеспечение возможно выполнять лабораторные работы и измерять исследуемые устройства.
The object of research is the device DIY Vector Network Analyzer UVNA-63. The purpose of the work is to develop software for DIY Vector Network Analyzer UVNA-63. This paper describes software development in Matlab. The operation of the developed measurement functions is described. The work of the developed graphical interface is described. Refinement of the laboratory work methodology. The relevance of the work is justified by the lack of software for carrying out measurements on a vector network analyzer, which is at the disposal of the department and can be used in the educational process. The developed software will make it possible to carry out measurements, calibrate the apparatus, save the obtained data in various formats, display the obtained data on a graph and set markers on the graph. The scope is the educational area. With the help of the developed software, it is possible to carry out laboratory work and measure the investigated devices.

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Ultra-Wideband (UWB) technology has become very famous amongst the radar imaging community. This system is well suited for tomographic imaging as it offers high special resolution and a low probability of detection. Some of the UWB applications include ground penetrating radar, medical imaging and some military applications. In this thesis an UWB radar imaging system has been designed and implemented using an Agilent E5071B Vector Network Analyzer and a rotating pedestal. The two ports of the device are used as a transmitter and receiver, measuring the frequency domain data of the scene in front of the antennas at each angular position as the rotating pedestal rotates in front of the antennas. This data is then put through a time domain back-projection algorithm which reconstructs an image of the scene. This is done in 2D space and then later extended to 3D space.

In this report we focus on the use of an economical way on how Scalar Network Analyzer (SNA) works instead of Vector Network Analyzer (VNA) to estimate the phase angle of signals in indoor channel. This is detailed in RMS delay theory and simulation section, experimental is designed in the according Experiment Design section, where we also state the required measurements known from the math part. In our work, data are recorded both from two different channel characteristics. Method of achieving amplitude is by using deconvolution theory. The condition of applying Hilbert transform are highlighted as impulse response h(t) in time domain should be causal.  The recorded data amplitude is computed by Hilbert Transform, and therefore validate the condition using Inverse Discrete Fourier Transform (IDFT) back to time domain to achieve h(t). Power delay profile P(t) is therefore presented afterwards. In paper calculations of rms delay τrms  of the channel which is the most important variable are also performed, the results calculated from different windowing truncation and the LOS and NLOS characteristics are compared in discussion and conclusion section, it also includes Opinions of window functions chosen for the phase estimation.

L’avènement des interfaces tactiles ouvre des perspectives d’enrichissement de l’interaction entre l’homme et la machine. Nous proposons un nouveau concept de surfaces tactiles souples dont l’objectif est d’étudier l’interaction entre le signal électrique et l’environnement résistif et diélectrique du support, afin de réaliser le système d’acquisition fournissant une information exploitable par la machine.La base technologique est un guide d’ondes sur substrat souple sur lequel le toucher crée une réflexion au port d’entrée. Nous avons développé une méthode de localisation alternative à la réflectométrie temporelle, nommée Harmonic Detection and Location (HDL), permettant l’utilisation d’une électronique d’acquisition de faible complexité, en bande étroite, autour de 100 MHz. Le concept a été validé à partir de mesures sur des dalles tactiles souples et rigides connectées à un analyseur de réseau, utilisé comme référence. Un système d’acquisition compact basé sur un pont de Wheatstone associé à un détecteur de phase a été développé. Pour ce faire, un travail de caractérisation et d’identification des sources d’erreurs a été mené sur les interactions électromagnétiques entre le doigt et le guide d’onde, les imperfections du guide d’onde et la nature du substrat ainsi que l’impact des erreurs induites par l’électronique d’acquisition.Cette connaissance a permis de co-développer la partie matérielle et l’algorithme de détection pour démontrer une précision de localisation de 2cm. Les fondamentaux posés dans ce travail ouvrent la possibilité de réalisation d’interfaces de grande surface, avec une connectique simple, conformables sur des objets sensitifs en trois dimensions
The advent of sensitive interfaces is promising prospects to the human-machine interaction. We propose a new concept of sensitive flexible surface. Its aim is to study the interaction between electrical signal and resistive and dielectric environment of the support in order to realize an acquisition system providing machine readable information.The technological base is a waveguide on flexible substrate on which the touch creates a reflection at the input port. We have developed a location method as an alternative to the time domain reflectometry (TDR). It is named Harmonic Detection and Location (HDL) and it allows using a narrow band, around 100 MHz, low complexity acquisition system. The concept has been approved using measures on flexible and rigid sensitive surfaces connected to a vector network analyzer (VNA) used as reference. A compact acquisition system based on a Wheatstone bridge associated to a phase detector has been developed. For this purpose, errors characterization and identification work has been done. Electromagnetic interactions between the finger and the waveguide, waveguide imperfections, substrate nature and acquisition system errors’ impact have been studied. This knowledge has provided the possibility to co-develop the hardware and the detection algorithm to demonstrate a location accuracy of 2cm. Fundamental principles of this work provide the possibility of realizing large surface interfaces, with simple connection and conformable, for 3D sensitive objects

Due to the ever-increasing worldwide consumption of memory for digital information, new technologies for higher capacity and faster data storage systems have been the focus of research and development. A step towards achieving higher data storage densities or magnetic recording media is the concept of bit patterned media, where the magnetic recording layer is divided up into magnetically isolated bit units. This approach is one of the most promising technologies for increasing data storage densities and could be implemented by nanostructuring the wafer. Therefore, the fabrication of the appropriate nanostructures on a small scale and then be able to manufacture these structures on an industrial scale is one of the problems where science and industry are working on a solution. In addition, the answer to the open question about the influence that patterning on the nano length scale has on the magnetic properties is of great interest. The main goal of this thesis is to answer the open question, which magnetic properties can be tailored by a modification of the surface texture on the nanometre length scale. For this purpose the following properties: anisotropy, remanence, coercivity, switching field distribution, saturation magnetisation, Gilbert damping, and inhomogeneous linebroadening were compared between planar two dimensional thin ferromagnetic films and three dimensional magnetic structures. In addition, the influences of the tailored morphology on the intergranular or the exchange coupling between the structures, which is called interdot exchange coupling, was investigated. For the ferromagnetic thin films, the focus of the investigations was on the granular CoCrPt:SiO2 and [Co/Pd] layer, which currently are the state-of-the-art material for magnetic data storage media. These materials are characterised by their high coercivity and high perpendicular anisotropy, which has a low spatial distribution in the preferred direction of magnetisation. In this work the pre-structured GaSb(001) substrate with self-assembled periodic nanocone structures at the surface are used. The preparation by ion beam erosion of these structures is simple, fast, and highly reproducible and therefore this method is particularly beneficial for fundamental research. To compare the 2D thin films with the 3D magnetic structures, besides the pre-structured specimen, planar samples were also fabricated. The first sample series prepared was coated by Py. Due to the fact that the magnetic properties of this material are well-known, it was also possible to do some OOMMF simulations in addition to the VNA-FMR and MOKE measurements. Afterwards two planar samples with CoCrPt and CoCrPt:SiO2 were prepared. The planar CoCrPt:SiO2 samples were Co+ ion implanted to study the influence of such irradiation on the intergranular and interdot exchange coupling, switching field distribution, and in particular on the spin dynamics. Moreover, both samples were measured by TRMOKE in order to obtain information about the spin dynamics. Subsequently, the perpendicular storage media materials CoCrPt:SiO2 and [Co/Pd] were deposited on a prestructured GaSb(001) nanocone substrate surface. These sample series were measured by MOKE, SQUID, and vector-VSM. The measurements demonstrate the influence of the periodicity and height of the nanocones on the intergranular and interdot exchange coupling. They also show the reorientation of the magnetisation with respect to the curvature of the substrate template and furthermore, the morphology-induced influences on the magnetic domains. From the comparison between the results for the planar and the pre-structured samples, a decrease of the interdot exchange coupling was observed, which scales together with the periodicity of the nanocone pattern. In addition, it was shown that for all samples with thin magnetic films on nanocones,the magnetisation aligns along the curvature of the underlying nanocone structure. For Py on nanocones, planar granular CoCrPt:SiO2, and planar granular CoCrPt, measurements by VNA-FMR and TRMOKE could be carried out, which yielded information about the spin dynamics. The results obtained for both of the planar sample are comparable to values from the literature for the Gilbert damping. The results for the Py samples showed that the commonly used 2D model resonance condition is, in case of a 3D magnetic structure, no longer valid due to the alignment of the magnetisation along the underlying substrate structure and therefore an new model has to be derived
Aufgrund des weltweiten, immer weiter steigenden Bedarfs an Speicherplatz von digitalen Information, sind neue Technologien für größere und schnellere Speichermedien im Fokus von Forschung und Entwicklung. Ein Schritt hin zu einer höheren Speicherdichte in der magnetischen Datenspeicherung ist dabei das sogenannte Konzept der ”Bit patterned media”, das definierte Informationseinheiten auf regelmäßig angeordneten Nanostrukturen beschreibt. Dieser Ansatz ist einer der derzeit vielversprechendsten Optionen die Speicherdichte zu erhöhen. Dabei ist die Herstellung der benötigten Nanostrukturen und deren Skalierung hin zu makroskopischen Dimensionen eines der Probleme an deren Lösung die Wissenschaft und Industrie derzeit arbeitet. Desweiteren ist die Antwort auf die noch offene Frage nach der Beeinflussung der nanoskaligen Strukturen auf die magnetischen Eigenschaften von großem Interesse. Das Hauptziel in dieser Arbeit ist es, einen Beitrag zur Beantwortung der Frage, welche magnetischen Eigenschaften sich durch eine Veränderung der Oberflächenstruktur im Nanometerbereich beeinflussen lassen, zu leisten. Hierzu wurden die folgenden Eigenschaften, wie zum Beispiel die Anisotropie, Remanenz,Koerzitivität, Schaltfeldverteilung, Sättigungsmagnetisierung, Gilbertdämpfung und inhomogene Linienverbreiterung von planaren zweidimensionalen dünnen ferromagnetische Schichten mit denen von dreidimensionalen magnetischen Strukturen verglichen. Zusätzlich wurde der Einfluss der angegpassten Morphologie auf die intergranularen- beziehungsweise auf die zwischen den Strukturen wirkende (interdot) Austauschkopplung untersucht. Der Hauptaugenmerk bei den ferromagnetisch dünnen Schichten lag dabei auf den granularen CoCrPt:SiO2 und [Co/Pd] Filmen, die heutzutage ein Standardmaterial für die magnetischen Speichermedien darstellen. Diese Materialien zeichnen sich durch eine hohe Koerzivität und senkrechte Anisotropie, mit geringer räumlicher Verteilung der Vorzugsrichtung der Magnetisierung, aus. Die hier vorgestellten vorstrukturierten GaSb(001) Substrate mit selbstordnenden periodischen Nanokegeln auf der Oberfläche, sind mittels Ionenstrahlerosion einfach, schnell und sehr gut reproduzierbar herzustellen. Deshalb ist diese Methode besonders für die Grundlagenforschung von Vorteil. Um einen Vergleich zwischen 2D Filmen und 3D Strukturen ziehen zu können, wurden neben den vorstrukturierten Substraten auch planare Proben beschichtet. Eine erste Versuchsreihe wurde mit einem dünnen Py Film präpariert. Da dessen magnetische Eigenschaften wohlbekannt sind, konnten neben den Untersuchungen mit VNA-FMR und MOKE auch einige OOMF Simulationen erstellt werden. Danach wurden zwei Proben mit planarem CoCrPt beziehungsweise CoCrPt:SiO2 untersucht. Bei den planaren CoCrPt:SiO2 Proben wurden außerdem noch Co+ Ionen implantiert, um deren Auswirkungen auf die intergranulare Austauschkopplung, Schaltfeldverteilung und besonders auf die Spindynamik zu bestimmen. Bei beiden Probensystemen konnte zusätzlich die Spindynamik mittels zeitaufgelöstem MOKE gemessen werden. Im Anschluss wurden die beiden senkrechten Speichermedien CoCrPt:SiO2 and [Co/Pd] auf Substraten mit Nanokegeln vorstrukturierten GaSb(001) Oberflächen abgeschieden. Diese Proben wurden mit MFM, MOKE, SQUID und Vektor-VSM vermessen. Aus den Messungen konnnten dann die Einflüsse auf die intergranulare- beziehungsweise interdot Austauschkopplung in Abhängigkeit von der Periodizität und Höhe der Nanokegel bestimmt werden, sowie die Umorientierung der Magnetisierung bezüglich der Substratkrümmung und den Morphologie induzierten Einfluss auf die magnetischen Domänen. Anhand der Vergleiche zwischen den Messungen der planaren und den vorstrukturierten Proben konnte eine Verringerung der Austauschkopplung zwischen den Strukturen gezeigt werden, die mit der Nanokegelstrukturperiodizität skaliert. Außerdem wurde in allen dünnen magnetischen Filmen auf Nanokegeln gezeigt, dass die Magnetisierung sich in Abhängigkeit der darunterliegenden Struktur ausrichtet. Bei den Py auf Nanokegeln, den planaren CoCrPt und dem planaren CoCrPt:SiO2 Proben konnten außerdem mit VNA-FMR und TRMOKE Informationen bezüglich der Spindynamik gemessen werden. Die erzielten Ergebnisse, der beiden planaren Proben, sind vergleichbar mit denen, aus der Literatur bekannten Werten, für die Gilbertdämpfung. Darüber hinaus wurde durch die Messungen an den Py Proben gezeigt, dass die Theorie, des bisher genutzten 2D Modells, nicht mehr gültig ist, da sich die Magnetisierung entlang der Substratstruktur ausrichtet, und deshalb ein neues Model aufgestellt werden muss

Due to the ever-increasing worldwide consumption of memory for digital information, new technologies for higher capacity and faster data storage systems have been the focus of research and development. A step towards achieving higher data storage densities or magnetic recording media is the concept of bit patterned media, where the magnetic recording layer is divided up into magnetically isolated bit units. This approach is one of the most promising technologies for increasing data storage densities and could be implemented by nanostructuring the wafer. Therefore, the fabrication of the appropriate nanostructures on a small scale and then be able to manufacture these structures on an industrial scale is one of the problems where science and industry are working on a solution. In addition, the answer to the open question about the influence that patterning on the nano length scale has on the magnetic properties is of great interest. The main goal of this thesis is to answer the open question, which magnetic properties can be tailored by a modification of the surface texture on the nanometre length scale. For this purpose the following properties: anisotropy, remanence, coercivity, switching field distribution, saturation magnetisation, Gilbert damping, and inhomogeneous linebroadening were compared between planar two dimensional thin ferromagnetic films and three dimensional magnetic structures. In addition, the influences of the tailored morphology on the intergranular or the exchange coupling between the structures, which is called interdot exchange coupling, was investigated. For the ferromagnetic thin films, the focus of the investigations was on the granular CoCrPt:SiO2 and [Co/Pd] layer, which currently are the state-of-the-art material for magnetic data storage media. These materials are characterised by their high coercivity and high perpendicular anisotropy, which has a low spatial distribution in the preferred direction of magnetisation. In this work the pre-structured GaSb(001) substrate with self-assembled periodic nanocone structures at the surface are used. The preparation by ion beam erosion of these structures is simple, fast, and highly reproducible and therefore this method is particularly beneficial for fundamental research. To compare the 2D thin films with the 3D magnetic structures, besides the pre-structured specimen, planar samples were also fabricated. The first sample series prepared was coated by Py. Due to the fact that the magnetic properties of this material are well-known, it was also possible to do some OOMMF simulations in addition to the VNA-FMR and MOKE measurements. Afterwards two planar samples with CoCrPt and CoCrPt:SiO2 were prepared. The planar CoCrPt:SiO2 samples were Co+ ion implanted to study the influence of such irradiation on the intergranular and interdot exchange coupling, switching field distribution, and in particular on the spin dynamics. Moreover, both samples were measured by TRMOKE in order to obtain information about the spin dynamics. Subsequently, the perpendicular storage media materials CoCrPt:SiO2 and [Co/Pd] were deposited on a prestructured GaSb(001) nanocone substrate surface. These sample series were measured by MOKE, SQUID, and vector-VSM. The measurements demonstrate the influence of the periodicity and height of the nanocones on the intergranular and interdot exchange coupling. They also show the reorientation of the magnetisation with respect to the curvature of the substrate template and furthermore, the morphology-induced influences on the magnetic domains. From the comparison between the results for the planar and the pre-structured samples, a decrease of the interdot exchange coupling was observed, which scales together with the periodicity of the nanocone pattern. In addition, it was shown that for all samples with thin magnetic films on nanocones,the magnetisation aligns along the curvature of the underlying nanocone structure. For Py on nanocones, planar granular CoCrPt:SiO2, and planar granular CoCrPt, measurements by VNA-FMR and TRMOKE could be carried out, which yielded information about the spin dynamics. The results obtained for both of the planar sample are comparable to values from the literature for the Gilbert damping. The results for the Py samples showed that the commonly used 2D model resonance condition is, in case of a 3D magnetic structure, no longer valid due to the alignment of the magnetisation along the underlying substrate structure and therefore an new model has to be derived.
Aufgrund des weltweiten, immer weiter steigenden Bedarfs an Speicherplatz von digitalen Information, sind neue Technologien für größere und schnellere Speichermedien im Fokus von Forschung und Entwicklung. Ein Schritt hin zu einer höheren Speicherdichte in der magnetischen Datenspeicherung ist dabei das sogenannte Konzept der ”Bit patterned media”, das definierte Informationseinheiten auf regelmäßig angeordneten Nanostrukturen beschreibt. Dieser Ansatz ist einer der derzeit vielversprechendsten Optionen die Speicherdichte zu erhöhen. Dabei ist die Herstellung der benötigten Nanostrukturen und deren Skalierung hin zu makroskopischen Dimensionen eines der Probleme an deren Lösung die Wissenschaft und Industrie derzeit arbeitet. Desweiteren ist die Antwort auf die noch offene Frage nach der Beeinflussung der nanoskaligen Strukturen auf die magnetischen Eigenschaften von großem Interesse. Das Hauptziel in dieser Arbeit ist es, einen Beitrag zur Beantwortung der Frage, welche magnetischen Eigenschaften sich durch eine Veränderung der Oberflächenstruktur im Nanometerbereich beeinflussen lassen, zu leisten. Hierzu wurden die folgenden Eigenschaften, wie zum Beispiel die Anisotropie, Remanenz,Koerzitivität, Schaltfeldverteilung, Sättigungsmagnetisierung, Gilbertdämpfung und inhomogene Linienverbreiterung von planaren zweidimensionalen dünnen ferromagnetische Schichten mit denen von dreidimensionalen magnetischen Strukturen verglichen. Zusätzlich wurde der Einfluss der angegpassten Morphologie auf die intergranularen- beziehungsweise auf die zwischen den Strukturen wirkende (interdot) Austauschkopplung untersucht. Der Hauptaugenmerk bei den ferromagnetisch dünnen Schichten lag dabei auf den granularen CoCrPt:SiO2 und [Co/Pd] Filmen, die heutzutage ein Standardmaterial für die magnetischen Speichermedien darstellen. Diese Materialien zeichnen sich durch eine hohe Koerzivität und senkrechte Anisotropie, mit geringer räumlicher Verteilung der Vorzugsrichtung der Magnetisierung, aus. Die hier vorgestellten vorstrukturierten GaSb(001) Substrate mit selbstordnenden periodischen Nanokegeln auf der Oberfläche, sind mittels Ionenstrahlerosion einfach, schnell und sehr gut reproduzierbar herzustellen. Deshalb ist diese Methode besonders für die Grundlagenforschung von Vorteil. Um einen Vergleich zwischen 2D Filmen und 3D Strukturen ziehen zu können, wurden neben den vorstrukturierten Substraten auch planare Proben beschichtet. Eine erste Versuchsreihe wurde mit einem dünnen Py Film präpariert. Da dessen magnetische Eigenschaften wohlbekannt sind, konnten neben den Untersuchungen mit VNA-FMR und MOKE auch einige OOMF Simulationen erstellt werden. Danach wurden zwei Proben mit planarem CoCrPt beziehungsweise CoCrPt:SiO2 untersucht. Bei den planaren CoCrPt:SiO2 Proben wurden außerdem noch Co+ Ionen implantiert, um deren Auswirkungen auf die intergranulare Austauschkopplung, Schaltfeldverteilung und besonders auf die Spindynamik zu bestimmen. Bei beiden Probensystemen konnte zusätzlich die Spindynamik mittels zeitaufgelöstem MOKE gemessen werden. Im Anschluss wurden die beiden senkrechten Speichermedien CoCrPt:SiO2 and [Co/Pd] auf Substraten mit Nanokegeln vorstrukturierten GaSb(001) Oberflächen abgeschieden. Diese Proben wurden mit MFM, MOKE, SQUID und Vektor-VSM vermessen. Aus den Messungen konnnten dann die Einflüsse auf die intergranulare- beziehungsweise interdot Austauschkopplung in Abhängigkeit von der Periodizität und Höhe der Nanokegel bestimmt werden, sowie die Umorientierung der Magnetisierung bezüglich der Substratkrümmung und den Morphologie induzierten Einfluss auf die magnetischen Domänen. Anhand der Vergleiche zwischen den Messungen der planaren und den vorstrukturierten Proben konnte eine Verringerung der Austauschkopplung zwischen den Strukturen gezeigt werden, die mit der Nanokegelstrukturperiodizität skaliert. Außerdem wurde in allen dünnen magnetischen Filmen auf Nanokegeln gezeigt, dass die Magnetisierung sich in Abhängigkeit der darunterliegenden Struktur ausrichtet. Bei den Py auf Nanokegeln, den planaren CoCrPt und dem planaren CoCrPt:SiO2 Proben konnten außerdem mit VNA-FMR und TRMOKE Informationen bezüglich der Spindynamik gemessen werden. Die erzielten Ergebnisse, der beiden planaren Proben, sind vergleichbar mit denen, aus der Literatur bekannten Werten, für die Gilbertdämpfung. Darüber hinaus wurde durch die Messungen an den Py Proben gezeigt, dass die Theorie, des bisher genutzten 2D Modells, nicht mehr gültig ist, da sich die Magnetisierung entlang der Substratstruktur ausrichtet, und deshalb ein neues Model aufgestellt werden muss.

Questo elaborato si pone l’obiettivo principale di formulare una metodologia volta alla misura sperimentale della risposta impulsiva di ambienti indoor in ambito acustico. Lo studio della risposta impulsiva di una stanza trova diverse applicazioni nell’ambito dell’ingegneria acustica. Essa contiene infatti informazioni sulla geometria della stanza stessa, che può essere ricostruita con appositi algoritmi. È sovente impiegata anche in campo architettonico per progettare interventi di correzione o ottimizzazione acustica. In questo elaborato si darà spazio ad una terza applicazione: si utilizzerà la risposta impulsiva misurata in una determinata stanza per aggiungere effetti ambientali a suoni registrati in camere anecoiche. Per perseguire quest’obiettivo, nel capitolo 1 si richiamano i concetti di base riguardo i sistemi LTI, funzioni di trasferimento e risposta impulsiva, approfondendo gli aspetti legati alle tecniche tradizionalmente usate per la misura della risposta impulsiva in ambito acustico. Si pone poi la base teorica del metodo sperimentale che sarà sviluppato nel corso dell’elaborato, fondato sulla stima numerica dello spettro di segnali ad energia finita. Nel secondo capitolo s’illustra l’impostazione della catena di misura, chiarendo le scelte hardware intraprese, le motivazioni di tali scelte, il funzionamento generale dei dispositivi impiegati e le condizioni ottimali di misura. Il capitolo 3 rappresenta il cuore di questo elaborato, nel quale viene illustrata l’implementazione vera e propria della metodologia della misura della risposta impulsiva, a partire dal settaggio degli strumenti utilizzati, alla realizzazione del codice MATLAB per l’elaborazione dei dati, per giungere infine all’analisi dei risultati sperimentali ottenuti. Con il quarto ed ultimo capitolo si introduce il concetto di equalizzazione e si implementa una prima e grossolana soluzione al problema degli effetti distorcenti introdotti dai dispositivi non ideali.

Объектом исследования является дискретный фазовращатель ДМВ диапазона. Цель работы - разработка фазовращателя с требуемыми в техническом задании параметрами. В процессе работы был рассчитан и смоделирован фазовращатель в среде проектирования «АWR Design Environment», разработана электрическая принципиальная схема и перечень элементов, создан макет устройства и проведены его измерения. Моделирование ФВ проводилось с применением методов электромагнитного анализа и использованием в качестве основных активных элементов их S-параметров и Spice-моделей. В результате проведенной работы был создан макет фазовращателя с требуемыми параметрами. Результаты работы будут применены при создании фазированной антенной решетки метеорологического радиолокатора.
The object of the research is a discrete phase shifter of the UHF range. The purpose of the work is to develop a phase shifter with the parameters required in the technical specification. In the process of work, the phase shifter was calculated and modeled in the AWR Design Environment, an electrical schematic diagram and a list of elements were developed, a device model was created and its measurements were carried out. PV modeling was carried out using the methods of electromagnetic analysis and using their S-parameters and Spice-models as the main active elements. As a result of the work carried out, a prototype of a phase shifter with the required parameters was created. The results of the work will be used to create a phased array of a meteorological radar.

In biomedical applications realistic phantoms are becoming more useful for validation and testing of precursor systems. These artificial phantoms require stable and flexible tissue-mimicking materials with realistic dielectric properties in order to properly model human tissues. We have fabricated a low-water-content, low cost, mechanically and electrically stable, good shelf life and multi-layered heterogeneous phantom consisting of skin, fat and muscle tissues. We have chosen semi-solid type phantom for each tissue layer. The size and thickness of the each layer is chosen based on the average thickness of human tissue. Altering the ingredient composition wisely we can alter its dielectric properties also. By reason of no osmosis occurrence, the tissues can be employed to construct heterogeneous phantoms or even anthropomorphic phantoms without causing any changes in geometry or electrical properties. The performance of the fabricated phantom is carried out using an open-ended coaxial slim probe system by Agilent Technologies. Nearly all previous studies were based on very high frequency( VHF), so we present ultra-wide band (UWB), 500MHz-20GHz multilayered phantoms. We have measured our phantom after 2 month time period and we got quite good results for the dielectric properties without having significant variations. Thus, our fabricated sets of ATE phantom have good long lasting properties with good physical and dielectric stability.

This thesis describes possibilities of measuring permittivity of various materials, especially with coaxial probe method. It describes character of measuring method, hardware requirements and how to calculate values from the measured. Objective of this thesis is to design measuring station for measuring permittivity of materials with coaxial probe including calibration set. Code in Matlab is also programmed and whole station is tested with known samples to discuss measurement accuracy.

Abstract This dissertation presents complete parameterizations for a three-dimensional (3-D) geometry-based stochastic radio channel model (GSCM) at 10 GHz based on measurement campaigns. The thesis is divided into the following main parts: radio channel measurements, the characterization of model parameters, and model validation. Experimental multiple-input multiple-output (MIMO) channel measurements carried out in two-story lobby and urban small cell scenarios are first described. The measurements were performed with a vector network analyzer and dual polarized virtual antenna arrays with a bandwidth over 500 MHz. The measurement data was post-processed using the ESPRIT algorithm and the post-processed data was verified using a semi-deterministic map-based model. The results showed a good match between estimated and modeled multipath components (MPCs). In addition, single-input single-output outdoor-to-indoor measurements were executed through a standard multi-pane glass window and concrete wall. A statistical analysis was carried out for defining full 3-D characterization of the propagation channel in both line-of-sight (LOS) and non-line-of-sight (NLOS) propagation conditions. The delay and angular dispersions of MPCs are smaller in comparison to lower frequency bands due to the higher attenuation of the delayed MPCs. Moreover, specular reflection is observed to be the more dominant propagation mechanism in comparison to diffuse scattering, leading to smaller cluster angle spreads in comparison to lower frequency bands. The penetration loss caused by a standard multi-pane glass window is on the same level as in the lower frequency bands, whereas the loss caused by the concrete wall is a few dBs higher than at lower frequency bands. Finally, the GSCM with determined parameters is validated. A MIMO channel was reconstructed by embedding 3-D radiation patterns of the antennas into the propagation path estimates. Equivalently the channel simulations were performed with a quasi deterministic radio channel generator (QuaDRiGa) using the defined parameters. The channel capacity, Demmel condition number, and relative condition numbers are used as the comparison metrics between reconstructed and modeled channels. The results show that the reconstructed MIMO channel matches the simulated MIMO channel well
Tiivistelmä Tämä väitöskirja esittää parametroinnit kolmiulotteiselle geometriaan perustuvalle stokastiselle radiokanavamallille 10 GHz:n taajuusalueella perustuen mitattuun radiokanavaan. Väitöskirja koostuu kolmesta pääalueesta: radiokanavamittaukset, radiokanavamallin parametrien määrittäminen ja mallin validointi. Aluksi kuvataan kaksikerroksisessa aula ja kaupunkipiensolu ympäristöissä monilähetin monivastaanotin (MIMO) järjestelmällä tehdyt kanavamittaukset. Mittaukset tehtiin vektoripiirianalysaattorilla ja kaksoispolaroiduilla virtuaaliantenniryhmillä 500 MHz kaistanleveydellä. Mittausdata jälkikäsiteltiin käyttämällä ESPRIT-algoritmia ja jälkikäsitelty data varmennettiin osittain deterministisellä mittausympäristön karttaan pohjautuvalla radiokanavamallilla. Tulokset osoittivat hyvän yhteensopivuuden mitattujen ja mallinnettujen moniteiden välillä. Lisäksi toteuttiin yksi-lähetin yksi-vastaanotin mittaukset ulko-sisä etenemisympäristössä monikerroksisen lasin ja betoniseinän läpi. Tilastollinen analyysin avulla määritettiin täysi kolmiulotteinen kuvaus radioaallon etenemiskanavasta näköyhteys ja näköyhteydettömässä tilanteissa. Moniteiden suuremmista vaimennuksista johtuen viive ja kulmahajonnat ovat pienemmät verrattaessa matalempiin taajuuksiin. Peiliheijastus on diffuusisirontaa merkittävämpi radioaallon etenemismekanismi johtaen pienempiin klustereiden kulmahajeisiin matalempiin taajuuksiin verrattuna. Monikerroksisen lasin läpäisyvaimennus on samankaltainen kuin alemmilla taajuuksilla, kun sitä vastoin betoniseinän vaimennus on muutaman desibelin suurempi kuin alemmilla taajuuksilla. Lopulta geometriaan perustava stokastinen radiokanavamalli validoidaan määritellyillä parametreilla. MIMO kanava uudelleen rakennetaan lisäämällä kolmiulotteiset antennien säteilykuviot estimoituihin radioaallon etenemisteihin. Vastaavasti radiokanava simuloidaan näennäisesti deterministisellä radiokanavageneraattorilla (QuaDRiGa) käyttäen määriteltyjä mallin parametreja. Kanavakapasiteettia, Demmel ehtolukua ja suhteellista ehtolukua käytetään vertailumittareina uudelleen rakennetun ja simuloidun kanavan välillä. Tulosten perusteella uudelleen rakennettu MIMO kanava on yhteensopiva simuloidun radiokanavan kanssa

Des circuits différentiels sont largement utilisés pour la conception de composants hyperfréquences principalement en raison de leur meilleure immunité au bruit. Ces circuits doivent être caractérisés au moyen de paramètres S en mode mixte (mode différentiel, mode commun et conversion entre les deux modes). De plus, la tendance à la miniaturisation et à l’intégration des dispositifs hyperfréquences conduit à l’utilisation de structures planaires ou coplanaires telles que les lignes micro-ruban ou les lignes coplanaires. La structure coplanaire avec les conducteurs déposés à la surface supérieure du substrat évite de réaliser des trous métallisés, et donc simplifie la fabrication et empêche l’apparition d’éléments parasites. Du point de vue de la métrologie électrique, il est nécessaire d’établir la traçabilité des mesures de paramètres S en mode mixte au Système International d’unités (SI). La méthode d’étalonnage Multimode Thru – Reflect – Line (TRL), dérivée de l’étalonnage TRL couramment utilisée pour les mesures de paramètres S de circuits asymétriques, est bien adaptée à cette problématique. En effet, l’impédance caractéristique, qui définit l’impédance de référence du système de mesure, peut être obtenue à partir des constantes de propagation déterminées lors de la procédure Multimode TRL et des capacités linéiques en DC.Nous présentons la première conception et la réalisation d’un kit d’étalonnage Multimode TRL et d’un kit de vérification à base des lignes coplanaires couplées en configuration « Ground – Signal – Ground – Signal – Ground » sur un substrat de quartz (SiO2) à faibles pertes diélectriques pour des mesures de paramètres S en mode mixte sur wafer de 1 GHz à 40 GHz. Les mesures sont effectuées à l’aide de deux méthodes : l’approche « one-tier » basée sur la procédure d’étalonnage Multimode TRL afin de déterminer et de corriger l’ensemble des erreurs systématiques ou bien l’approche « two-tier » qui fractionne la détermination et la correction des termes d’erreur en deux étapes dont la deuxième est associée à la méthode Multimode TRL. La faisabilité et la validation de ces techniques sont démontrées par des mesures d’éléments de vérification, constitués de lignes (adaptées, désadaptées et déséquilibrées) et d’atténuateurs en T, qui montrent un très bon accord entre les valeurs mesurées et simulées.La propagation des incertitudes est évaluée soit à partir du calcul des dérivées partielles à l’aide de l’outil Metas.Unclib ou bien par simulation numérique basée sur la méthode de Monte Carlo. La précision des mesures de paramètres S sous pointes dépend des sources d’influence attribuées aux mesures et aux imperfections des étalons telles que le bruit et la non-linéarité de l’analyseur de réseaux vectoriel, la stabilité des câbles, la répétabilité des mesures et la sensibilité dans la réalisation des étalons. Faute de temps, nous nous limitons à estimer la propagation d’incertitudes liées à la répétabilité de mesure des étalons et du dispositif sous test (DST) aux valeurs des paramètres S corrigés de la ligne désadaptée. Les résultats montrent que l’approche des dérivées partielles basée sur une approximation de la série de Taylor au premier ordre ne peut pas être utilisée avec précision à cause de l’influence significative de la non-linéarité des fonctions mathématiques de l’algorithme Multimode TRL. La méthode Monte Carlo s’avère alors plus précise bien qu’elle nécessite des temps de calcul très longs
Differential circuits are widely used in the design of high frequency components mainly because of their better noise immunity. These circuits can be characterized using mixed-mode S parameters (differential- and common-mode S-parameters and cross-mode terms). Furthermore, the trend toward miniaturization and integration of microwave devices increases the need for planar or coplanar microwave integrated circuits such as micro-strip lines or coplanar waveguides. The ungrounded coplanar waveguide structure with all the conductors located on the same side of the substrate eliminates the need for via-holes, and thus simplifies manufacturing and prevents the appearance of some parasitic elements. From the viewpoint of electrical metrology, it is necessary to establish the traceability of the mixed-mode S-parameter measurements to the International System of Units (SI). The Multimode Thru-Reflect-Line (TRL) calibration method, derived from the commonly-used TRL calibration for S-parameter measurements of single-ended circuits, is particularly well suited for this purpose as the standards are traceable via dimensional measurements. The characteristic impedance, which defines the reference impedance of the measurement system, can be achieved from the propagation constants determined during the Multimode TRL calibration and the capacitances per unit length of the transmission line.We present the first design and realization of Multimode TRL calibration and verification kits using coupled coplanar lines in the "Ground - Signal - Ground - Signal - Ground" configuration on quartz (SiO2), the low-loss substrate, for on-wafer mixed-mode S-parameter measurements from 1 GHz to 40 GHz. Measurements are performed using two methods: the “one-tier” technique, based on the Multimode TRL calibration procedure, determines and corrects all systematic errors. The “two-tier” approach, in which the Multimode TRL is applied at the second-tier, is applied to measurement data that were partially corrected by the first calibration. The feasibility and the validation of the methods are demonstrated by measurements of matched, mismatched and unbalanced lines and T-attenuators showing good agreement between simulated and measured results.The propagation of uncertainty can be derived by the calculation of partial derivatives using the Metas.Unclib tool or by the numerical approach based on the Monte Carlo technique. The accuracy of on-wafer S-parameter measurements depends on sources of influence attributed to the measurements and to the imperfections of the standards such as the VNA noise and non-linearity, the cable stability, the measurement repeatability, and the sensitivity in calibration standards’ realization. We focus, first and foremost, on the propagation of uncertainties related to the repeatability of the standards and the device under test measurements to the corrected mixed-mode S-parameters of the mismatched line. The results show that the partial derivatives approach based on an approximation of the first-order Taylor series cannot be accurately used due to the significant influences of non-linear functions in the Multimode TRL algorithm. The Monte Carlo method is then more precise although it requires very long computation time

In the present work, the implications of ion irradiation on the magnetostatic and dynamic properties of soft magnetic Py/Ta (Py = Permalloy: Ni80Fe20) single and multilayer films have been investigated with the main objective of finding a way to determine their saturation magnetization. Both polar magneto-optical Kerr effect (MOKE) and vector network analyzer ferromagnetic resonance (VNA-FMR) measurements have proven to be suitable methods to determine µ0MS, circumventing the problem of the unknown effective magnetic volume that causes conventional techniques such as SQUID or VSM to fail. Provided there is no perpendicular anisotropy contribution in the samples, the saturation magnetization can be determined even in the case of strong interfacial mixing due to an inherently high number of Py/Ta interfaces and/or ion irradiation with high fluences. Another integral part of this work has been to construct a VNA-FMR spectrometer capable of performing both azimuthal and polar angle-dependent measurements using a magnet strong enough to saturate samples containing iron. Starting from scratch, this comprised numerous steps such as developing a suitable coplanar waveguide design, and writing the control, evaluation, and fitting software. With both increasing ion fluence and number of Py/Ta interfaces, a decrease of saturation magnetization has been observed. In the case of the 10×Py samples, an immediate decrease of µ0MS already sets in at small ion fluences. However, for the 1×Py and 5×Py samples, the saturation magnetization remains constant up to a certain ion fluence, but then starts to rapidly decrease. Ne ion irradiation causes a mixing and broadening of the interfaces. Thus, the Py/Ta stacks undergo a transition from being polycrystalline to amorphous at a critical fluence depending on the number of interfaces. The saturation magnetization is found to vanish at a Ta concentration of about 10–15 at.% in the Py layers. The samples possess a small uniaxial anisotropy, which remains virtually unaffected by the ion fluence, but slightly reduces with an increasing number of Py/Ta interfaces. In addition to magnetostatics, the dynamic properties of the samples have been investigated as well. The Gilbert damping parameter α increases with both increasing number of Py/Ta interfaces and higher ion fluences, with the former having a stronger influence. The inhomogeneous linewidth broadening ΔB0 increases as well with increasing number of Py/Ta interfaces, but slightly decreases for higher ion fluences.
In dieser Dissertation ist der Einfluss von Ionenbestrahlung auf die magnetostatischen und dynamischen Eigenschaften von weichmagnetischen Py/Ta-Einzel- und Multilagen (Py = Permalloy: Ni80Fe20) untersucht worden, wobei das Hauptziel gewesen ist, eine Methode zur Bestimmung der Sättigungsmagnetisierung zu finden. Sowohl polare magneto-optische Kerr-Effektmessungen (MOKE) als auch ferromagnetische Resonanzmessungen mittels eines Vektornetzwerkanalysators (VNA-FMR) haben sich als geeignet erwiesen, um µ0MS zu bestimmen, wobei das Problem des unbekannten effektiven magnetischen Volumens umgangen wird, welches bei der Verwendung von Techniken wie SQUID oder VSM auftreten würde. Unter der Voraussetzung, dass die Proben keinen senkrechten magnetischen Anisotropiebeitrag besitzen, kann die Sättigungsmagnetisierung selbst im Fall starker Grenzflächendurchmischung infolge einer großen Anzahl an Py/Ta-Grenzflächen und/oder Ionenbestrahlung mit hohen Fluenzen bestimmt werden. Ein weiterer wesentlicher Bestandteil dieser Arbeit ist die Konstruktion eines VNA-FMR-Spektrometers gewesen, welches vollautomatisiert ist, polare und azimutale Winkelabhängigkeiten messen kann und einen Magneten besitzt, der Proben, die Eisen beinhalten, sättigen kann. Von Grund auf beginnend umfasste dies zahlreiche Schritte wie z. B. die Entwicklung eines geeigneten koplanaren Wellenleiterdesigns sowie das Schreiben von Steuerungs-, Auswertungs- und Fitprogrammen. Mit steigender Fluenz und Zahl an Py/Ta-Grenzflächen ist eine Abnahme der Sättigungsmagnetisierung beobachtet worden. Im Fall der 10×Py-Proben findet diese bereits bei kleinen Fluenzen statt. Im Gegensatz dazu bleibt µ0MS der 1×Py- und 5×Py-Proben bis zu einer bestimmten Fluenz konstant, bevor sie sich dann umso schneller verringert. Die Bestrahlung mit Ne-Ionen verursacht eine Durchmischung und Verbreiterung der Grenzflächen. Infolgedessen erfahren die Py/Ta-Proben bei einer kritischen Fluenz, die von der Zahl der Grenzflächen abhängig ist, einen Phasenübergang von polykristallin zu amorph. Die Sättigungsmagnetisierung verschwindet ab einer Ta-Konzentration von etwa 10–15 Atom-% in den Py-Schichten. Die Proben besitzen eine kleine uniaxiale Anisotropie, die praktisch unbeeinflusst von der Fluenz ist, sich jedoch mit steigender Zahl an Py/Ta-Grenzflächen leicht verringert. Neben den statischen sind auch die dynamischen magnetischen Eigenschaften der Proben untersucht worden. Der Gilbert-Dämpfungsparameter α erhöht sich sowohl mit steigender Zahl an Py/Ta-Grenzflächen als auch mit höheren Fluenzen, wobei Erstere einen größeren Einfluss hat. Die inhomogene Linienverbreiterung ΔB0 nimmt ebenfalls mit steigender Zahl an Py/Ta-Grenzflächen zu, verringert sich jedoch bei größeren Fluenzen leicht.

RCs (Reverberation Chambers) has historically been used mainly for aerospace and military purposes in EMC (Electromagnetic Compatibility) testing, but the interest also seems to increase in the automotive industry (the development of an international standard for vehicles is in progress). The vehicles of the future will most likely be electrified, wirelessly connected and autonomous, i.e., more control units, more communication systems, and more sensors, will be implemented in the vehicles requiring increased robustness against all possible electromagnetic interferences. EMC testing in an RC is a step in the direction of ensuring this robustness for the future vehicle platforms. Compared to a traditional EMC test method in a fully or semi-AC (Anechoic Chamber), testing in an RC has the advantage that the electromagnetic field will be isotropic, randomly polarized and homogeneous in a statistical sense, i.e., the exposed object will be surrounded by electromagnetic energy from all directions. It can be considered relatively expensive to build a brand new RC with motorized stirrers and associated measurement instrumentation, instead it would be desirable to perform immunity tests in a more cost-effective conductive fabric tent. The great advantage is the flexibility, the tent can be set up almost anywhere, even in already existing semi-ACs, such set-up is referred to as VIRC (Vibrating Intrinsic Reverberation Chamber). This thesis aims to develop a new test method in a VIRC environment. In order to achieve good RC conditions, the electromagnetic field must be statistically Rayleigh distributed. Furthermore, it is of great importance to avoid LoS (Line of Sight) between the antenna and the test object, and to achieve good stirring in the tent. Provided this can be achieved, there are still some challenges by testing in a tent. For example, the classical dwell time of two seconds for immunity testing in EMC is not possible to achieve in a VIRC environment. The validation in this thesis shows that the dwell time or the total exposure time in the tent might be enough to trigger possible malfunctions in today's modern high-speed communication vehicles. Furthermore, it is showed, testing in a VIRC gives good field uniformity and repeatability, and can trigger malfunctions that are not triggered in traditional EMC testing in semi-AC, i.e., ALSE (Absorber-Lined Shielded Enclosure) testing.

碩士
中華大學
電機工程學系碩士班
99
In this thesis is to device PXI Vector Network Analyzer Which including RF ports multiplexer module and RF signal processing module circuit board, then add NI (National Instruments) PXI instrument module and LABVIEW software enabled to reach automatic measurement. Chapter 2 is the system planning of PXI Vector Network Analyzer. Chapter 3 & 4 to discuss the device idea and approbation of RF ports multiplexer module and RF signal management mold circuit board which are used on PXI Vector Network Analyzer. Chapter 5 is the design idea and approbation of the device of PXI Vector Network Analyzer. The main purpose of PXI Vector Network Analyzer is to cost down the testing platform and to replace the traditional expensive machine. Except to be used on PXI Vector Network Analyzer for both RF ports multiplexer module and RF signal management mold, they are also applicable to be used on other testing purposes to achieve one card for multiple functions.

碩士
國立交通大學
電信工程研究所
86
A vector network analyzer is an important instrument for measuring and characterizing RF or microwave devices and components. We can obtain the transmission and reflection characteristics of RF of microwave devices by using a vector network analyzer. Most network analyzers currently sold on the markets adopt a super-heterodyne receiver architecture for its measurements. This architecture is a measurement method in frequency domain. The frequency of a signal source change continuously to trigger the device under test (DUT). Then the frequency response of our desired band can be detected by the receiver. Some calibration laboratory might use a six-port network analyzer in order to achieve more accurate measurement results, nevertheless at the expanse of much higher system complexity and cost. Another way to do network analysis is to use very high speed pulses and conduct measurements in the time domain. This method is still under development in some research laboratories. In this article, we propose a new vector network analyzer architecture. We use the sliding correlator techniques commonly employed in a spread spectrum communication system to design a vector network analyzer. A sliding correlator technique is based on the time domain sliding effect caused by a small clock frequency offset in the pseudo random code generators of a transmitter and a receiver. Utilizing the periodic impulse train like autocorrelation function property of the pseudonoise (PN) code sequence, the receiver is able to measure the characteristics of the device under test (DUT). A time scaled version of the impulse response of the device under test (DUT) can be obtained from the time domain slided pseudo random code signals by using a correlator. A fast Fourier transform of the measured impulse response is the frequency response of the device under test. This paper describes how to design a vector network analyzer based on the sliding correlator technique and analyzes the advantage of using this method.

碩士
國立雲林科技大學
材料科技研究所
106
In this study, the ferromagnetic resonance phenomena induced by different structure and process parameters were investigated for the CoFeB film with in-plane anisotropy. The samples of structure Sub/Co40Fe40B20(X nm)/MgO(0 or 5 nm) were deposited by ultra-high vacuum sputtering system, where the Co40Fe40B20 thickness ranges from 5 to 30 nm. By using the scanning-frequency ferromagnetic resonance system combined with Vector Network analyzer (VNA) and Conductor-Backed coplanar waveguide (CBCPW) are analyzed. In this study, the resonance phenomenon was observed by changing the external magnetic field (0~800 Gauss) and Sweep range (300k~10 GHz). The dynamic magnetic properties such as Lande g-factor and damping constant (α) were obtained by fitting the experimental data. The research contents of this thesis include: The influences of MgO capping layer and substrate quality, thickness of different magnetic layer and annealing processes on dynamic magnetic properties. The resonant frequency dependences on applied in-plane field for all the experimental data follow the typical Kittel equation, The g-factors can be obtained by fitting these experiment curves. The result shows that the capping layer, substrate, magnetic film thickness and annealing processes have no effect on the g-factor, and g is the fixed value 2.153±0.310. The damping constant decreases inversely with magnetic film thickness, and the annealing processes increase the damping constant substantially. The results of this study are helpful to understand the origin of the dynamic magnetic properties of the CoFeB film structure, and to clarify the factors inducing the resonance phenomenon. The established parameter database is beneficial to the development and research of the future spin electronic components.

碩士
國立臺灣大學
電子工程學研究所
95
Conventionally, we have to know the value of at least one terminator in advance when measuring multi-port network by using two-port vector network analyzer. [16] proposed the algorithm for three-port to two-port port reduction method with unknown terminators. [17] proposed the algorithm which can reconstruct the multi-port network with known terminator from three-port or more port scattering matrices. This work adopt the main idea of these two works and implement with Matlab program. The measured scattering matrices of a branch line coupler on FR4 substrate using proposed port reduction method shows good agreement with measurement by multi-port VNA.

博士
國立臺灣大學
電信工程學研究所
92
In this dissertation, novel techniques are developed for microwave imaging and circuit calibration using vector network analyzer (VNA). For microwave imaging applications, based on two-port VNA, three measurement systems are designed for quasi-monostaitc, bistatic and multistatic frequency-swept microwave imaging. Firstly, in Chapter 2, a quasi-monostatic frequency-swept microwave imaging system using multi-source illumination is proposed to have an efficient scattered field acquisition arrangement. Furthermore, the measurement system, calibration method and experimental results are presented. In order to implement the two-source and two-receiver multistatc arrangement, in Chapter 3, a new four-port test set is developed to connect with VNA for multistatic microwave imaging. In Chapter 4, the principle, measurement system, calibration and experimental results of bistatic microwave imaging in a multi-source illumination arrangement are presented. The experimental results shown in Chapter 2, 3 and 4 demonstrate that the three cost-effective imaging systems developed in this dissertation can improve the image resolution, object aspect angle and the efficiency of Fourier-domain data acquisition in comparison with the microwave imaging system using monostatic or bistatic arrangement with single-source illumination. For microwave circuit calibration applications, four novel calibration techniques are proposed in Chapter 5 to solve the difficulties in microwave circuit measurements using VNA. Firstly, a new test set with two-port stimulus is developed to avoid the switch leakage errors. Instead of TRL (thru, reflection, line) self-calibration procedure with limited frequency range, this test set exploits the wideband on-wafer TAN (thru, attenuation, network) calibration procedure to correct the measurement systematic errors. Secondly, the differential TRL calibration procedure is developed to improve the differential-type discontinuity measurement. Thirdly, in order to evaluate the performance of a single flip-chip interconnect, the TRL and LRL (short line, reflection, long line) calibration procedures are combined as a two-step de-embedding procedure to measure the characteristics of flip-chip interconnects. Finally, a novel three-port calibration method using three three-port calibrators is developed to calibrate a three-port VNA. It has the potential as an effective method to calibrate a multi-port VNA using multi-port calibrators.

碩士
國立中央大學
通訊工程研究所碩士在職專班
96
When technologies have been moving very fast still high speed digital application becomes more and more popular in different applications. PC peripheral as good example, in order to improve the whole performance, we should link each component in efficient way. For CPU and VGA card, we have PCI-Express2 interface in front side bus. For data storage, we have SATA2/ SATA3 to interface with H.D.D. data transferring. For Display, there is high quality video technology as HDMI 1.3 and display port. For internet, we have 10 Gbps Ethernet as optical fiber communication to reach longer distance than before. The speed requests from 3 GHz to 10 GHz and later application will definitely need higher speed to fulfill bandwidth requirement. To make high speed dream world real, digital circuit designs dominate the differential topology which shows benefit of low power consumption and noise suppression. As test standard defined by SATA or HDMI society, mixed-mode S-parameter is one of the necessary items for applying the certification logo. But as compared to traditional Vector Network Analyzer, its 2-port and single ended structure cannot meet modern applications. Another choice is using virtual or true differential 4-port VNA announced after 2001. In order to reutilize the 2-port VNA, we generate the test set combined with microwave switches. With hardware switching function, we defined the individual signal path that could leverage 4-port differential measurement. We also use TDR technique in time domain platform to verify the measurement accuracy. Furthermore, this technique also provides the methodology of equivalent circuit that for further ADS simulation. In this thesis, we utilize two types of transmission line and an on-wafer LNA as the device under test, to prove the proposed algorithm, and we also use real 4-port VNA as reference for performance verification.

This PhD thesis work is about the development of radio frequency oriented measurement and characterization approaches for mixed-signal devices. Mixed-signal devices are an important building block for newer, higher data-rate and smart radios. However, intuitive and simple characterization approaches have not yet been developed. The most basic mixed-signal device is an ADC or a DAC. The ADCs and DACs will be considered in this work, as well as, more complex mixed-signal devices and even entire (integrated) radio front-ends. A microwave network analysis approach, in an S-parameters like fashion, will be used to augment the modeling techniques of mixed-signal devices. This type of behavioral modeling approach is extensively supported within the tools used during the RF design stages. This will allow RF engineers to account for the non-ideal effects of these devices in a simpler way. The final outcome may be used to establish an instrument capable to characterize both basic and more complex mixed-signal devices, in the same way a traditional VNA does for fully analog devices.
Este trabalho de doutoramento aborda o desenvolvimento de técnicas de medida e caracterização, usando uma perspetiva de radiofrequência, para dispositivos analógico-digitais. Os dispositivos analógico-digitais são blocos importantes no desenho de novos rádios, com maior velocidade de troca de dados, ou mesmo rádios inteligentes. As ADCs e DACs podem ser consideradas como os dispositivos analógico-digitais mais simples. Neste trabalho vão ser consideradas as ADCs e DACs, bem como dispositivos analógico-digitais mais complexos, ou mesmo cadeias completas de rádio. Uma abordagem baseada na análise de circuitos de micro-ondas, semelhante `a utilizada pelos ‘parâmetros S’, vai ser utilizada para expandir as técnicas de caracterização dos dispositivos analógico-digitais. Este tipo de caracterização comportamental ´e suportada amplamente pelas ferramentas utilizadas durante o desenvolvimento de aparelhos rádio. Esta técnica vai permitir aos engenheiros de RF considerar os efeitos não-ideais deste tipo de dispositivos, de uma forma mais simples. O resultado final deste trabalho poder´a vir a ser utilizado para estabelecer um instrumento capaz de caracterizar dispositivos analógico-digitais simples ou mais complexos, da mesma forma que um VNA é utilizado para dispositivos puramente analógicos.
Programa Doutoral em Engenharia Eletrotécnica