No description available.

No description available.

This research solves current RF propagation modeling gaps by modifying a single-frequency electromagnetic propagation analysis technique for use on communication signals and propagation channels. This research extended the Methods of Ordered Multiple Interactions (MOMI) algorithm to communication signal propagation studies through the use of Fourier decomposition thereby allowing the analysis and prediction of communication signals propagating over rough surfaces. Current methods of predicting and analyzing communication signal propagation rely on either using only a single frequency instead of a band of frequencies, stochastic techniques that model the environmental effect on the propagated signal, or on empirical models based of large amounts of measured situational data. None of these methods fully capture the actual effect that an environment imparts on a communication signal as it propagates. This research also modifies the Physical Optics (PO) algorithm utilizing Fourier decomposition to compare the Extended MOMI algorithm to. Both algorithms are applied to propagation scenarios utilizing frequencies in the 1-GHz and 5-GHz bands against a series of signal bandwidths and surface roughnesses. The results are analyzed singularly for Extended-MOMI and against Extended-Physical Optics to better understand the benefits associated with using the Extended-MOMI, the limits of the narrowband approximation, the errors incurred when utilizing a simpler or faster propagation algorithm, and to generally characterize these rough surface propagation channels. This research also defines and explores which metrics provide the best characterization and utility for communication signal propagation with the additional insights of amplitude-frequency-phase relationships the new algorithm provides. / Doctor of Philosophy / Communication signal propagation, defined as the propagation of signals that have non-zero bandwidths from one point to another, has significant importance in communication signal design, system design, and deployment as well as in spectrum planning applications. Current methods of predicting and analyzing communication signal propagation rely on either using only a single frequency instead of a band of frequencies, stochastic techniques that model the environmental effect on the propagated signal, or on empirical models based of large amounts of measured situational data. None of these methods fully capture the actual effect that an environment imparts on a communication signal as it propagates. A technique that accurately models the environmental effect on propagating communication signals would result in knowledge about a communication signal strength and shape as it passes through the propagation space. Analyzing communication signals with single frequency propagation algorithms requires assuming all the frequencies that make up the communication signal propagate exactly the same way, an assumption known as the narrowband approximation. It is not known when the narrowband approximation breaks down in various circumstances. Consequently a more rigorous approach needed to be identified to enable a more accurate and complete analysis of communication signals, which is the objective of the research. This research solves these modeling gaps by modifying a single-frequency electromagnetic propagation analysis technique, the Method of Ordered Multiple Interactions, for use on communication signals and propagation channels. The new algorithm, Extended-MOMI, allows for an examination of communication signal propagation over rough surfaces. This new algorithm incorporates all of the information needed for communication signal propagation analysis; something that is missing from current methods. This technique enables tailored communication signal propagation studies as well as an investigations into when the narrowband assumption is valid and when simpler and faster algorithms could be utilized for a now known increase in error. This research also explores which metrics are best utilized with the additional signal information the new algorithm enables.

<p>I denna uppsats beskrivs metoder för att skapa en arm i 3D samt att lägga in den i ett foto där den ersätter en riktigt arm. Anledningen till detta är att kunna skapa effekter i filmer och bilder som inte är möjliga med analog teknik. I denna uppsats kan man läsa om tekniker som används i varje del av utvecklingsprocessen och problem som uppstår samt lösningar och tips. I uppgiften finns det med delar som Modellering, Texturering, Rendering, Kamera Matchmoving och Compositing.</p>

abstract: A domain decomposition method for analyzing very large FDTD domains, hundreds of thousands of wavelengths long, is demonstrated by application to the problem of radar scattering in the maritime environment. Success depends on the elimination of artificial scattering from the “sky” boundary and is ensured by an ultra-high-performance absorbing termination which eliminates this reflection at angles of incidence as shallow as 0.03 degrees off grazing. The two-dimensional (2D) problem is used to detail the features of the method. The results are cross-validated by comparison to a parabolic equation (PE) method and surface integral equation method on a 1.7km sea surface problem, and to a PE method on propagation through an inhomogeneous atmosphere in a 4km-long space, both at X-band. Additional comparisons are made against boundary integral equation and PE methods from the literature in a 3.6km space containing an inhomogeneous atmosphere above a flat sea at S-band. The applicability of the method to the three-dimensional (3D) problem is shown via comparison of a 2D solution to the 3D solution of a corridor of sea. As a technical proof of the scalability of the problem with computational power, a 5m-wide, 2m-tall, 1050m-long 3D corridor containing 321.8 billion FDTD cells has been simulated at X-band. A plane wave spectrum analysis of the (X-band) scattered fields produced by a 5m-wide, 225m-long realistic 3D sea surface, and the 2D analog surface obtained by extruding a 2D sea along the width of the corridor, reveals the existence of out-of-plane 3D phenomena missed by the traditional 2D analysis. The realistic sea introduces random strong flashes and nulls in addition to a significant amount of cross-polarized field. Spatial integration using a dispersion-corrected Green function is used to reconstruct the scattered fields outside of the computational FDTD space which would impinge on a 3D target at the end of the corridor. The proposed final approach is a hybrid method where 2D FDTD carries the signal for the first tens of kilometers and the last kilometer is analyzed in 3D. / Dissertation/Thesis / Doctoral Dissertation Electrical Engineering 2018

No description available.

The potential for high spatio-temporal resolution microwave measurements has urged the adoption of the signals of opportunity (SoOp) passive radar technique for use in remote sensing. Recent trends in particular target highly complex remote sensing problems such as root-zone soil moisture and snow water equivalent. This dissertation explores the continued open-sourcing of the SoOp coherent bistatic scattering model (SCoBi) and its use in soil moisture sensing applications. Starting from ground-based applications, the feasibility of root-zone soil moisture remote sensing is assessed using available SoOp resources below L-band. A modularized, spaceborne model is then developed to simulate land-surface scattering and delay-Doppler maps over the available spectrum of SoOp resources. The simulation tools are intended to provide insights for future spaceborne modeling pursuits.

Diese Arbeit untersucht den Einfluss der elektronischen Bandstruktur von Festkörperoberflächen auf den resonanten Ladungsaustausch zwischen Festkörpern und atomaren Projektilen. Dazu wurden diese atomaren Projektile an einkristallinen Cu(111)- und Cu(110)-Oberflächen gestreut. Die Streuung erfolgt unter streifendem Einfall, typischerweise bei Einfallswinkeln zwischen 0.5 bis zu 4 Grad zur Oberfläche bei Projektilgeschwindigkeiten von 0.05 bis zu 1.4 atomaren Einheiten. Unter diesen Bedingungen erfolgt kein Eindringen des Projektils in den Festkörper, sondern eine Reflektion des Projektils von der Oberfläche. Somit können die Ladungszustände der auslaufenden Projektile als Funktion von Projektilgeschwindigkeit und Einfallswinkel untersucht werden. Die Verteilung der Ladungszustände nach der Streuung hängt theoretischen Vorhersagen zufolge signifikant von der Bandstruktur der Festkörperoberfläche ab. Die Experimente wurden an zwei verschiedenen Cu-Oberflächen durchgeführt. Während die Cu(110)-Oberfläche gut durch das Modell des freien Elektronengases (jellium-Modell) beschrieben werden kann, ist die Cu(111)-Oberfläche durch eine Bandlücke im Bereich der Fermienergie sowie durch einen in der Bandlücke liegenden Oberflächenzustand gekennzeichnet. Um den Effekt der elektronischen Bandstruktur auf den resonanten Ladungsaustausch zwischen Festkörperoberflächen und atomaren Zuständen deutlich herauszustellen, wurden atomare Zustände, die sich energetisch in Resonanz zur Bandlücke befinden, untersucht. Insbesondere wurde der Ladungsaustausch von negativen Wasserstoff-, Fluor-, Chlor-, Sauerstoff-, Kohlenstoff- und Schwefelionen sowie der Grund- und angeregten Zustände von Lithium, Natrium und Kalium mit Cu(110)- und Cu(111)-Oberfläche experimentell untersucht. Die Neutralisation hochgeladener Ionen an einer Cu(111)-Fläche wurde stellvertretend am Beispiel von bis zu 21-fach geladenen Xenonionen studiert. Gravierende Effekte der elektronischen Bandstruktur der Cu(111)-Oberfläche wurden durch die Theorie für die Formierung negativer Wasserstoffionen vorhergesagt. Nach den Ergebnissen der WPP-Methode wird das Maximum der Abhängigkeit der H- -Ausbeute von der Parallelgeschwindigkeit bei 6% erwartet, während bei einer jellium-Oberfläche gleicher Austrittsarbeit und Fermienergie nur etwa 0.3% negativer Ionen vorhergesagt werden. Mit einer experimentell ermittelten H- -Ausbeute von maximal 1% wird ein signifikanter Einfluß der elektronischen Bandstruktur auf den Ladungsaustausch bestätigt. Der Verlauf der Geschwindigkeitsabhängigkeit der Ausbeute an negativen Ionen, insbesondere die Breite der Resonanzstruktur, deutet in Übereinstimmung mit der theoretischen Vorhersage auf eine dominante Beteiligung des Oberflächenzustandes am resonanten Ladungsaustausch hin. Die Differenz zwischen experimentellen und theoretischen Ergebnissen wird durch die Existenz eines zusätzlichen Elektronen-Verlustkanals erklärt. Die Berücksichtigung der Streuung an Festkörperelektronen führt zu einer wesentlichen Verbesserung der Übereinstimmung zwischen Experiment und Theorie. Die experimentelle Untersuchung der Neutralisation der Alkaliatome Lithium, Natrium und Kalium bestätigt einen signifikanten Einfluß der Bandlücke der Cu(111)-Oberfläche auf den resonanten Ladungsaustausch: Im Vergleich zur Vorhersage des jellium-Modells treten deutlich erhöhte Ausbeuten an neutralisierten Projektilen auf. Weiterhin finden sich in der Abhängigkeit der Neutralausbeuten von der Parallelgeschwindigkeit mehrere Maxima bzw. Schulterstrukturen, die auch von der WPP-Theorie qualitativ vorhergesagt werden. Die bei der Formierung negativer Halogenionen experimentell beobachtete Signatur der elektronischen Bandstruktur ist schwächer, als dies bei der Neutralisation von Alkaliatomen und der Formierung negativer Wasserstoffionen beobachtet werden konnte. Ein deutlicher Effekt der Bandlücke kann aber auch hier, wie auch bei der Streuung von Sauerstoff-, Kohlenstoff- und Schwefelionen, konstatiert werden. Die Untersuchung des Ladungsaustausches an der Cu(110)-Oberfläche ergab in allen Fällen eine gute Übereinstimmung mit der Vorhersage des jellium-Modells. Die in dieser Arbeit vorgestellten experimentellen Ergebnisse zeigen, daß die elektronische Bandstruktur der Cu(111)-Oberfläche den resonanten Ladungsaustausch substantiell beeinflußt. Das wurde besonders am Beispiel der Formierung negativer Wasserstoffionen und der Neutralisation von Alkaliatomen überzeugend demonstriert. Die Überzeugungskraft der experimentellen Ergebnisse wird durch die gute Übereinstimmung der an der (110)-Fläche des gleichen Metalls erzielten experimentellen Resultate mit den Vorhersagen des jellium-Modells erhöht. / This thesis investigates the influence of the electronic band structure of single crystal surfaces on the resonant charge transfer between solid and atomic projectiles. Atoms and ions were scattered off Cu(111)- and Cu(110) surfaces under grazing incidence conditions with angles of incidence between 0.5 to 4 degrees. Projectile velocities were varied between 0.05 and 1.4 atomic units. In this regime no penetration of the projectile into the solid occurs. Instead, the projectile is reflected from the crystal surface. Therefore the charge state distribution of scattered projectiles can be investigated as a function of the incidence conditions. According to theoretical predictions this charge state distribution strongly depends on the electronic band structure of the surface. The experiments were performed on 2 different Cu surfaces. While the Cu(110) surface can be well described by the free electron gas model (also refered to as jellium model), the Cu(111) surface is characterized by a bandgap around the Fermi energy and a surface state within this bandgap. To investigate the effect of the electronic band structure on the resonant charge transfer between solids and atoms/ions, the projectiles were choosen in a way that the atomic valence state is in resonance to the bandgap. In particular the formation of negative hydrogen, fluorine, chlorine, oxygen, carbon and sulfur ions as well as the population of ground and excited states of lithium, sodium and potassium in front of Cu(110) and Cu(111) surfaces was investigated. The neutralization of highly charged (up to 21 times positively charged) xenon ions in front of a Cu(111) surface was studied as well. A significant impact of the band structure of the Cu(111) surface has been theoretically predicted for the formation of negatively charged hydrogen ions. From wave packet propagation calculations 6% negative hydrogen ions are expected in front of a Cu(111) surface, compared to 0.3% that are expected for a jellium surface of the same work function and Fermi level. The experimental result of 1% confirms a significant influence of the electronic band structure on the charge exchange. The shape of the velocity dependence of the negative ion yield, in particular the width of this dependence, implies a dominant contribution of the surface state to resonant charge exchange in compliance with the theoretical predicition. The discrepancy between experimental data and theoretical prediction is explained by taking an additional electron loss channel into account. The consideration of scattering from electrons in the solid conduction band significantly improves the agreement between experimental and theoretical data. The investigation of the neutralization of the alkali atoms lithium, sodium and potassium confirms a significant influence of the electronic band structure of the Cu(111) surface on the resonant charge transfer. Significantly higher yields of neutralized projectiles as compared to the prediction of the jellium model are found. Furthermore the parallel velocity dependences of the neutral atom yield shows maxima or shoulder structures which are qualitavely reproduced by wave packet propagation calculations. The formation of negative halogen ions shows less pronounced effects of the Cu(111) surface band structure. However, also for these projectils a significant influence of the band structure on the resonant charge transfer is experimentaly confirmed. This holds as well for the formation of negatively charged oxygen, carbon and sulfur ions. The investigation of the resonant charge transfer in front of a Cu(110)surface resulted for all ions investigated in a good agreement between experiment and theory. The experimental results presented in the framework of this thesis show, that the electronic band structure of the Cu(111) surface has a substantiell impact on the resonant charge transfer. This has been presented in a particularly convincing way by the investigation of negative hydrogen ion and neutral alkali atom formation in front of a Cu(111) surface. The cogency of the experimental results is improved by the good agreement between the experimental results achieved at the Cu(110) surface and the theoretical prediction for a jellium metal.

To date only very few bistatic measurements (airborne or in controlled laboratories) have been reported. Therefore most of the current remote sensing methods are still focused on monostatic (backscatter) measurements. These methods, based on theoretical, empirical or semi-empirical models, enable the estimation of soil roughness and the soil humidity (dielectric constant). For the bistatic case only theoretical methods have been developed and tested with monostatic data. Hence, there still remains a vital need to gain of experience and knowledge about bistatic methods and data. The main purpose of this thesis is to estimate the soil moisture and the soil roughness by using full polarimetric bistatic measurements. In the experimental part, bistatic X-band measurements, which have been recorded in the Bistatic Measurement Facility (BMF) at the DLR Oberpfaffenhofen, Microwaves and Radar Institute, will be presented. The bistatic measurement sets are composed of soils with different statistical roughness and different moistures controlled by a TDR (Time Domain Reflectivity) system. The BMF has been calibrated using the Isolated Antenna Calibration Technique (IACT). The validation of the calibration was achieved by measuring the reflectivity of fresh water. In the second part, bistatic surface scattering analyses of the calibrated data set were discussed. Then, the specular algorithm was used to estimate the soil moisture of two surface roughnesses (rough and smooth) has been reported. A new technique using the coherent term of the Integral Equation Method (IEM) to estimate the soil roughness was presented. Also, the sensitivity of phase and reflectivity with regard to moisture variation in the specular direction was evaluated. Finally, the first results and validations of bistatic radar polarimetry for the specular case of surface scattering have been introduced. / Aktuell sind nur sehr wenige Messungen mit bistatischem Radar durchgeführt worden, sei es von Flugzeuggetragenen Systemen oder durch spezielle Aufbauten im Labor. Deshalb basieren die meisten der bekannten Methoden zur Fernerkundung mit Radar auf monostatis-chen Messungen der Rückstreuung des Radarsignals. Diese Methoden, die auf theoretischen, empirischen oder halb-empirischen Modellen basieren, ermöglichen die Schätzung der Oberfächenrauhigkeit und die Bodenfeuchtigkeit (Dielektrizitätskonstante). Im bistatischen Fall wurden bisher nur theoretische Modelle entworfen, die mittels monostatischer Messungen getestet wurden. Aus diesem Grund ist es von großer Bedeutung, Erfahrung und Wissen über die physikalischen Effekte in bistatischen Konfigurationen zu sammeln. Das Hauptziel der vorliegenden Dissertation ist es, anhand vollpolarimetrischer, bistatischer Radarmessungen die Oberfächenrauhigkeit und Bodenfeuchtigkeit zu bestimmen. Im experimentellen Teil der Arbeit werden die Ergebnisse bistatischer Messungen präsentiert, die in der Bistatic Measurement Facility (BMF) des DLR Oberpfaffenhofen aufgenommen wurden. Die Datensätze umfassen Messungen von Böden unterschiedlicher statistischer Rauhigkeit und Feuchtigkeit, die mittels eines Time Domain Reflectivity (TDR) Systems bestimmt werden. Zur Kalibration des BMF wurde die Isolated Antenna Calibration Technique (IACT) verwendet und anhand der Messung der Reflektivität von Wasser überprüft. Im zweiten Teil der vorliegenden Arbeit wird anhand der kalibrierten Daten eine Analyse der Oberflächenstreuung in bistatischen Konfigurationen vorgenommen. Im Anschluss daran wird mittels des Specular Algorithm eine Schätzung der Bodenfeuchte zweier Proben unter- schiedlicher Rauhigkeit (rau und fein) durchgeführt. Ein neues Verfahren zur Schätzung der Oberfächenrauhigkeit, das auf dem kohärenten Term der Integral Equation Method (IEM) basiert, wurde eingeführt. Daneben wird die Empfindlichkeit der Phase sowie der Reflektivität des vorwärtsgestreuten Signals gegenüber Veränderungen der Bodenfeuchtigkeit analysiert. Schließlich werden erste Ergebnisse und Validierungen bistatischer Radarpolarimetrie für den Fall der Vorwärtsstreuung präsentiert.

The 2006 International Technology Roadmap for Semiconductors projects that for 2020, interconnects will be as narrow as 14 nm and will operate at frequencies as high as 50GHz. For a wire that operates at ultra-high frequencies, such that skin depth and the mean free path of the electrons are in the same order, skin effect and surface scattering should be considered simultaneously. This is known as the anomalous skin effect (ASE). The objective of this work is to identify the challenges and opportunities for using GSI interconnects in the nanometer and GHz regime. The increase in the resistivity of a thin wire caused by the ASE is studied. The delay of a digital transmission line resulting from this effect is modeled. Compact models are presented for the bit-rate limit of transmission lines using a general form of resistance that for the first time simultaneously considers dc resistance, skin effect, and surface scattering. A conventional low-loss approximation that is only valid for fast rising signals is also relaxed. The impact of size effects on the design of multi-level interconnect networks is studied. For high-performance chips at the 18 nm technology node, it is shown that despite a more than four times increase in the resistivity of copper for minimum-size interconnects, the increase in the number of metal levels is negligible (less than 7%), and interconnects that will be affected most are so short that their impact on chip performance is inconsequential. It is shown that for low-cost applications where very few wiring pitches are normally used, the number of metal levels needed to compensate for the impact of size effects on the average rc delay of a copper interconnect is drastically high. An optimization methodology has been presented for power distribution interconnects at the local level. For a given IR drop budget, compact models are presented for the optimal widths of power and ground lines in the first two metal levels for which the total metal area used for power distribution is minimized.