13 research outputs found

    W-band photonic-wireless link with a Schottky diode envelope detector and bend insensitive fiber

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    The performance and potential of a W-band radio-over-fiber link is analyzed, including a characterization of the wireless channel. The presented setup focuses on minimizing complexity in the radio frequency domain, using a passive radio frequency transmitter and a Schottky diode based envelope detector. Performance is experimentally validated with carriers at 75–87GHz over wireless distances of 30–70m. Finally the necessity for and impact of bend insensitive fiber for on-site installation are discussed and experimentally investigated

    Wavelet-Coding for Radio over Fibre

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    Semiconductor Optical Amplifiers and mm-Wave Wireless Links for Converged Access Networks

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    Future access networks are converged optical-wireless networks, where fixed-line and wireless services share the same infrastructure. In this book, semiconductor optical amplifiers (SOA) and mm-wave wireless links are investigated, and their use in converged access networks is explored: SOAs compensate losses in the network, and thereby extend the network reach. Millimeter-wave wireless links substitute fiber links when cabling is not economical

    Laminat-Basierte Integrationsplattformen für Millimeterwellen-RoF-Photodioden-Module

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    This thesis investigates the potential offered by cost-effective printed circuit technology (PCT) for the packaging of mm-wave photodiode (PD) modules, as an alternative to the commonly used integration approaches based on thin/ thick-films or co-fired ceramics. We will therefore analyze the limitations imposed by this technology, focusing on the loss mechanisms and the theoretical frequency limits due to the material properties of the laminates and the RF circuitry concepts, as well as limitations imposed by the resolution and tolerances achievable in the printed circuit board (PCB) manufacturing processes. For the RF circuitry design, we will investigate characteristics and performances of traditional planar transmission lines (PTL), in particular microstrips and grounded coplanar waveguides (GCPW), and innovative substrate integrated waveguides (SIW). We will show that via holes play a fundamental role in the RF circuitry design, as they ultimately decide the highest possible frequency, independently of other parameters like conductor and dielectric loss, or etching inaccuracies. In fact, it is found that they are vital to guarantee a correct functioning of both GCPW and SIW, by avoiding board resonances and interferences between different lines. We will show that the current PCB via-hole technology allows the development of circuits working up to at least the upper limit of the W-band. As conventional microstrips are subject to higher radiation in the mm-wave region, GCPWs will be preferred for practical applications, also by virtue of their other practical advantages, such as easily accessible ground planes, increased design freedom, and extended impedance range. We will thus introduce the first concept of mm-wave PD modules with rectangular waveguide (WR) output for E-band Radio-over-Fiber (RoF) applications based on PCT integration boards. A particular feature of the proposed integration approach, is that a photonic transmitter can conveniently be assembled without any mechanical modifications of the WR, using standard off-the-shelf WR components, therefore simplifying the assembly process and reducing the cost of the module. We will also show that the availability of laminates with low moisture absorption as dielectric carrier furthermore opens up the possibility to develop quasi-hermetic packages without the need of dedicated radomes to seal the WR opening. The developed PD module will be used in mm-wave RoF demonstrators in order to prove the suitability of our approach for the development of commercial communication systems: We will be able to show a successful, error-free, 1-Gb/s, wireless connectivity in the 70-GHz communication band, with a power penalty limited to 1.5 dB. We will also present several additional prototypes, which include dedicated, on-board, biasing circuits, to allow integration of in-house-developed PDs and commercial amplifiers, and other solutions to reduce the loss of the signal power. In order to overcome the shortcomings of microstrips and GCPWs, such as unwanted radiation and increased power dissipation due to high current densities, we will then introduce for the first time the PCB SIW in the packaging of mm-wave photonic transmitters. The properties and advantages of this innovative transmission line in terms of low loss and high integration will be investigated and assessed, showing that its unique configuration allows a superior control of radiation and interferences, and drastically reduces losses. This suggests its use in all mm-wave systems where long on-board interconnects are required. A new integration approach for the development of quasi-hermetic PD modules with in-package antennas based on PCB SIW will thus be presented, focusing in particular on non-directive data distribution systems. It will be shown that compact, low-loss, and quasi-hermetic packaging solutions can conveniently be designed making use of the PCB SIW. We will furthermore introduce innovative GCPW-to-SIW transitions necessary for the integration of PDs on SIW platforms. Theoretically predicted performances will be compared with experimentally determined performances for a specifically optimized 60-GHz band GCPW-to-SIW transition. Also, the design and optimization of mm-wave antennas for indoor 60 GHz RoF systems will be presented, testing their performance against PCB manufacture inaccuracies. Finally, we will show an example of a fully characterized integration platform for PD modules, confirming the suitability of PCB SIW for the development of future, low-loss, and cost-effective photonic RoF transmitters.Diese Arbeit untersucht das Potenzial kostengünstige Leiterplattentechnik (PCT) für das Packaging von Millimeter-Wellen-Photodioden (PD) als Alternative zu den üblicherweise verwendeten Dünn-/ Dickschicht-Substraten oder co-fired Keramiken einzusetzen. Zunächst werden die physikalischen Grenzen dieser PCT-Technologie hinsichtlich eines Einsatzes bei höchsten Frequenzen untersucht. Die materialbedingten Verlustwinkel im Millimeter-Wellen-Bereich aber auch Abstrahlverluste im Zusammenhang mit verschiedenen planaren Schaltungs¬konzepten werden sowohl theoretisch als auch experimentell untersucht. Zum Einsatz kommen hierbei neben konventionellen planaren Übertragungsleitungen (PTL), wie Mikrostreifen und Grounded-Coplanar-Waveguides (GCPW), auch innovative Substrat-Integrierte-Wellenleiter (SIW). Weiterhin wird der Einfluss prozessbedingter Parameter, wie die minimal erreichbare Strukturgröße sowie Fertigungs¬toleranzen, auf das Hochfrequenzverhalten analysiert. Die Arbeit wird zeigen, dass Durchkontaktierungen (engl. Via Holes) eine fundamentale Rolle spielen. Unabhängig von anderen Einflussgrößen wie den dielektrischen Verlusten, den Abstrahlverlusten oder Fertigungstoleranzen begrenzt die minimal erreichbare Strukturgröße der Vias das Hochfrequenz¬verhalten der PCT-Technologie. Es wird theoretisch und experimentell nachgewiesen, dass die Vias für GCPW und SIW auf PCT-Technologie erforderlich sind, um geringe Ausbreitungsverluste zu gewährleisten, sowie um Resonanzen im Übertragungsverhalten und elektrischen Überkoppeln zwischen benachbarten Leitungen zu unterdrücken. Die Arbeit zeigt, dass die aktuelle PCB-Technologie die Entwicklung von planaren Hochfrequenz-Schaltungen erlaubt, die bis zur oberen Grenze des W-Bands (ca. 110 GHz) anwendbar sind. Da Mikrostreifenleitungen bekanntermaßen erhöhte Abstrahlverluste im Millimeterwellen-Bereich aufweisen, werden für technologische Realisierungen GCPWs vorgezogen. GCPW bieten gegenüber Mikrostreifenleitungen auch weitere Vorteile, wie leicht zugängliche Erdungsebenen, eine erhöhte Gestaltungsfreiheit und einen deutlich erweiterten Abstimmbereich der Leitungs-Impedanz. Basierend auf der PCT-Technologie und einer planaren GCPW-Schaltung wird im Folgenden ein neuartiger Ansatz für die Anbindung von hochfrequenten InP-basierten Photodioden-Chips an einen Rechteckhohlleiter entwickelt. Ein besonderes Merkmal des in dieser Arbeit vorgeschlagenen Integrationsansatzes besteht darin, dass sich das Photodioden-Modul ohne eine mechanische Modifikation des Hohlleiters realisieren lässt, was hinsichtlich Montageprozess und -kosten einen deutlichen Vorteil darstellt. Die Arbeit zeigt auch, dass die Verwendung von Laminaten mit geringer Feuchtigkeitsaufnahme weiterhin die Möglichkeit eröffnet, quasi-hermetische Module ohne die sonst erforderlichen Radome zu realisieren. Da eine wesentliche Anwendung für solche hochfrequenten Photodioden-Module im Bereich der Funkkommunikation und speziell für die Entwicklung von Punkt-zu-Punkt-Funkverbindungen im E-Band (60-90 GHz) liegt, konzentriert sich diese Arbeit auf die Entwicklung einer PCT-Integrationstechnologie für E-Band-Photodioden-Module mit WR-12 Hohlleiter. Die Arbeit beschreibt das Design und die Herstellung der GCPW-PCT-Schaltung. Die theoretisch simulierten Streuparameter der GCPW-PCT-Schaltung werden mit experimentellen Werten verglichen, bevor im Anschluss näher auf die erfolgreiche technologische Realisierung eines Prototyp-Photodioden-Moduls mit WR-12-Hohlleiterausgang eingegangen wird. Die Funktionalität des entwickelten PD-Moduls wird durch Einsatz in einer 70-GHz-Funkstrecke nachgewiesen. Es gelingt die Funkübertragung eines 1-Gbit/s-Datensignals im regulierten 70-GHz-Frequenzbereich (71-76 GHz). Die Arbeit zeigt im Anschluss weitere Prototypen, welche die Integration von hausintern entwickelten Photodioden und kommerziellen RF-Verstärkern erlauben, sowie Lösungen zur Reduzierung des Signalleistungsverlusts. Obwohl die verwendeten GCPW im Vergleich zu Mikrostreifenleitungen geringere Abstrahlverluste aufweisen, kommt es bei hohen Frequenzen doch zu einer unerwünschten Dämpfung durch Strahlungs- und ohmsche Verluste aufgrund der hohen Stromdichten in der GCPW-Schaltung. Zur weiteren Reduzierung dieser Verluste werden in dieser Arbeit daher erstmalig SIW-PCB-Schaltungen für die Integration von Millimeterwellen-Photodioden vorgeschlagen und entwickelt. Die Vorteile dieser innovativen Leitungsstruktur hinsichtlich der elektrischen Dämpfung im Millimeterwellen-Bereich werden theoretisch und experimentell untersucht. Es kann gezeigt werden, dass die SIW-PCT gegenüber den GCPW-PCT signifikant geringere Verluste aufweisen, was insbesondere für den Einsatz in planaren Hochfrequenz-Schaltungen mit vergleichsweise langen Verbindungsleitungen vorteilhaft ist. Die Arbeit präsentiert eine neue Integrationstechnologie auf Basis planarer SIW-PCB-Schaltungen für quasi-hermetische PD-Module mit In-Package-Antennen. Es werden kompakte, verlustarme und quasi-hermetische SIW-basierte Lösungen für 60-GHz-PD-Module hergestellt und experimentell untersucht. Abschließend wird die Eignung der SIW-PCB-Technologie für die Entwicklung zukünftiger, verlustarmer und kostengünstiger photonischer Millimeter-Wellen-Funktransmitter diskutiert

    1-D broadside-radiating leaky-wave antenna based on a numerically synthesized impedance surface

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    A newly-developed deterministic numerical technique for the automated design of metasurface antennas is applied here for the first time to the design of a 1-D printed Leaky-Wave Antenna (LWA) for broadside radiation. The surface impedance synthesis process does not require any a priori knowledge on the impedance pattern, and starts from a mask constraint on the desired far-field and practical bounds on the unit cell impedance values. The designed reactance surface for broadside radiation exhibits a non conventional patterning; this highlights the merit of using an automated design process for a design well known to be challenging for analytical methods. The antenna is physically implemented with an array of metal strips with varying gap widths and simulation results show very good agreement with the predicted performance

    Beam scanning by liquid-crystal biasing in a modified SIW structure

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    A fixed-frequency beam-scanning 1D antenna based on Liquid Crystals (LCs) is designed for application in 2D scanning with lateral alignment. The 2D array environment imposes full decoupling of adjacent 1D antennas, which often conflicts with the LC requirement of DC biasing: the proposed design accommodates both. The LC medium is placed inside a Substrate Integrated Waveguide (SIW) modified to work as a Groove Gap Waveguide, with radiating slots etched on the upper broad wall, that radiates as a Leaky-Wave Antenna (LWA). This allows effective application of the DC bias voltage needed for tuning the LCs. At the same time, the RF field remains laterally confined, enabling the possibility to lay several antennas in parallel and achieve 2D beam scanning. The design is validated by simulation employing the actual properties of a commercial LC medium

    Biomedical Engineering

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    Biomedical engineering is currently relatively wide scientific area which has been constantly bringing innovations with an objective to support and improve all areas of medicine such as therapy, diagnostics and rehabilitation. It holds a strong position also in natural and biological sciences. In the terms of application, biomedical engineering is present at almost all technical universities where some of them are targeted for the research and development in this area. The presented book brings chosen outputs and results of research and development tasks, often supported by important world or European framework programs or grant agencies. The knowledge and findings from the area of biomaterials, bioelectronics, bioinformatics, biomedical devices and tools or computer support in the processes of diagnostics and therapy are defined in a way that they bring both basic information to a reader and also specific outputs with a possible further use in research and development

    Wide Bandgap Based Devices: Design, Fabrication and Applications, Volume II

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    Wide bandgap (WBG) semiconductors are becoming a key enabling technology for several strategic fields, including power electronics, illumination, and sensors. This reprint collects the 23 papers covering the full spectrum of the above applications and providing contributions from the on-going research at different levels, from materials to devices and from circuits to systems

    Photodetectors

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    In this book some recent advances in development of photodetectors and photodetection systems for specific applications are included. In the first section of the book nine different types of photodetectors and their characteristics are presented. Next, some theoretical aspects and simulations are discussed. The last eight chapters are devoted to the development of photodetection systems for imaging, particle size analysis, transfers of time, measurement of vibrations, magnetic field, polarization of light, and particle energy. The book is addressed to students, engineers, and researchers working in the field of photonics and advanced technologies
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