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Yes / A novel beam-forming module based on Wilkinson power divider technology, including attenuators and phase shifter chips is designed, fabricated and evaluated to be incorporated in a Relay Station connecting it with the Base Station under a 4G network. The proposed module is a 1:8 port circuit, utilizing two substrates, providing approximately 700 MHz bandwidth over 3.5 GHz frequency band and less than −20 dB transmission line coupling. Moreover an external control unit that feeds the beam-forming module with code-words that define the proper amplitude/phase of the excitation currents is established and described. The presented module is connected to a planar array and tested for two beam-forming scenarios, providing satisfactory radiation patterns.

L’objectif de cette action R&T CNES est le développement en technologie intégrée SiGe BiCMOS d’un core-chip MMIC pour les antennes à formation de faisceaux. Les nouvelles solutions pour les charges satellites développées pour les applications télécom notamment ont besoin d’être de plus en plus flexibles. Cela passe par la mise en place d’un très grand nombre de points de contrôle RF ‘Amplitude/Phase’ qui alimentent les antennes actives. Il faut donc de nouvelles solutions pour optimiser ces fonctions. Ces solutions doivent répondre à plusieurs critères : être compactes, diminuer la consommation DC et conserver les mêmes niveaux de performance en termes de gain, résolution et linéarité que les solutions déjà en place. Dans ce contexte, notre projet de recherche a porté sur le développement de circuits déphaseurs et atténuateurs en technologie SiGe. Une étude préliminaire a permis d’évaluer la technologie en réalisant un premier run comprenant des cellules de déphasage et d’atténuation élémentaires. Des lignes de transmission de type Slow Wave Lines ont également été intégrées afin de montrer leur potentiel pour des applications futures. Ces premiers résultats ont conduits à réaliser un second run comprenant des circuits plus avancés ainsi que le test d’une nouvelle technique pour le design des transistors : le body floating. Cette technique nous a permis de diminuer les pertes de nos circuits tout en améliorant la linéarité. Un troisième run incluant un déphaseur et un atténuateur 4 bits a permis de confirmer les modèles de simulations et le potentiel des circuits MMIC en technologie SiGe. Un dernier run a enfin permis de réaliser un nouveau type de SWL et de réaliser des solutions alternatives aux circuits classiques basées sur ces dernières. / This R&T CNES project concerns the design and realization of a Core-chip MMIC system integrated in SiGe BiCMOS technology. The MMIC core-chip system is dedicated to the beamforming for the active satellite antenna. The new solutions for the satellite payloads being developed for telecommunication applications need an increased flexibility at all the levels. More precisely, the system of active antennas allowing an adjustment by real-time electronic command of the terrestrial covered area offers an optimized response for the communication link budget. This performance has a cost: the necessity of a very large number of RF control points "amplitude / phase" of the beamforming equipment which power the active antenna matrix elements. So, it becomes mandatory to bring a new solution to optimize this function. The main challenges are: increasing the functions integration, decreasing the DC power consumption and keeping the RF performances in terms of gain, resolution and linearity.

This thesis consist of a theoretical study of propagation effects in optical waveguides, fibres and photonic crystals, with some comparison with experiment.¶ Chapter 1 gives a brief introduction with the current view of optical components in photonic integrated circuits and issues related to the loss mechanism.¶ In Chapter 2 the characteristics of single-mode propagation and transient effects in practical square- and rectangular-core buried channel planar waveguides are quantified, assuming a cladding which is unbounded in one transverse dimension and bounded in the other. The wavelength cut-off condition for the fundamental mode is determined when the cladding index is asymmetric and composed of step-wise, uniform index regions.¶ In Chapter 3, the application of segmented reflection gratings in planar devices that can function as either a single- or two-wavelength add/drop filter is investigated and a numerical technique developed in Chapter 2 is applied to the waveguides with high extinction ratio. The role of the segmented gratings is analogous to that of a blazed grating, but they can provide a higher reflectivity level at the Bragg wavelength, eliminate back reflection into the fundamental mode and provide arbitrarily small channel spacing in the two-wavelength case.¶ Chapters 4 address the problem of bend loss in a single-mode slab waveguide. A new theoretical strategy for reducing bend loss is presented and compared to existing designs. The results obtained in this chapter are the basis for the following two chapters.¶ Chapter 5 deals with bend loss in single-mode buried channel waveguides and demonstrates that the new strategy can lead to significant bend loss reduction when compared to other strategies, and, conversely, can be used to enhance bend loss for a fixed bend radius for application to devices such as optical attenuators.¶ In Chapter 6, a novel design of a variable optical attenuator based on a bent channel waveguide is proposed, realized by applying a new strategy for bend loss control in a polymer buried channel waveguide.¶ Chapter 7 investigates effects of the additional rings in a single mode step-index fibre on bend loss. It is supported with the experimental results of Ron Bailey from Optical the Fibre Technology Centre, University in Sydney.¶ In Chapter 8, bend loss of a one-dimensional photonic crystal is quantified and compared to bend loss of a standard single-mode slab waveguide and a bend-resistant waveguide.¶

by John Reed.

This thesis proposes research of novel hybrid photonic signal processing systems in the areas of optical communications, test and measurement, RF signal processing and extreme environment optical sensors. It will be shown that use of innovative hybrid techniques allows design of photonic signal processing systems with superior performance parameters and enhanced capabilities. These applications can be divided into domains of analog-digital hybrid signal processing applications and free-space--fiber-coupled hybrid optical sensors. The analog-digital hybrid signal processing applications include a high-performance analog-digital hybrid MEMS variable optical attenuator that can simultaneously provide high dynamic range as well as high resolution attenuation controls; an analog-digital hybrid MEMS beam profiler that allows high-power watt-level laser beam profiling and also provides both submicron-level high resolution and wide area profiling coverage; and all optical transversal RF filters that operate on the principle of broadband optical spectral control using MEMS and/or Acousto-Optic tunable Filters (AOTF) devices which can provide continuous, digital or hybrid signal time delay and weight selection. The hybrid optical sensors presented in the thesis are extreme environment pressure sensors and dual temperature-pressure sensors. The sensors employ hybrid free-space and fiber-coupled techniques for remotely monitoring a system under simultaneous extremely high temperatures and pressures.

This graduate thesis is concerned with a comparative analysis of attenuators and intensifiers in Czech and Spanish language. The research has been conducted on Czech and Spanish journalist texts from major newspaper and magazines. The theoretical analysis starts by classifying expressions that are used to intensify or attenuate. The author follows the traditional Spanish classification which has been extended with expressions that she finds important. All expressions are examined from both the grammatical and expressive perspective. The analysis then continues by introducing the types of journalists texts used in the research. The research is based on comparison of attenuators and intensifiers in both languages and their influence on the reader.