We reinvestigate the validity of mapping the problem of two onsite interacting particles in a random potential onto an effective random matrix model. To this end we first study numerically how the non-interacting basis is coupled by the interaction. Our results indicate that the typical coupling matrix element decreases significantly faster with increasing single-particle localization length than is assumed in the random matrix model. We further show that even for models where the dependency of the coupling matrix element on the single-particle localization length is correctly described by the corresponding random matrix model its predictions for the localization length can be qualitatively incorrect. These results indicate that the mapping of an interacting random system onto an effective random matrix model is potentially dangerous. We also discuss how Imry's block-scaling picture for two interacting particles is influenced by the above arguments.

La conception de filtres hautes fréquences requiert l’optimisation des paramètres physiques du filtre afin d’obtenir une réponse en fréquence qui remplit les conditions imposées par le gabarit de fréquence. Cette optimisation dépend de simulations électromagnétiques. La résolution de ces équations aux dérivées partielles étant très couteuse en temps de calcul, nous proposons de développer des modèles pour le filtre qui permettent de réduire le nombre de simulations EM nécessaires au réglage du filtre. Le but recherché est d’incorporer ces modèles dans une méthode de conception assistée par ordinateur. Dans cette thèse, je propose différentes approches pour la modélisation du filtre. La première approche utilise la matrice de couplage du filtre, qu’elle décrit en fonction des paramètres physiques. La deuxième approche modélise les paramètres S en fonction de ces mêmes paramètres. Dans la première méthode, on se concentre essentiellement sur l’extraction de la matrice de couplage physique. On introduit une technique pour estimer la matrice de sensibilité (le Jacobien) qui lie les paramètres physiques aux paramètres de couplage. Cette estimation utilise les sensibilités adjointes des paramètres. L’utilisation de cette information réduit drastiquement le nombre de simulations EM et donc le temps de calcul global. Une deuxième approche utilise le concept de méta-modèle. L’idée maitresse de cette approche est que l’évaluation de ce modèle est numériquement beaucoup plus avantageuse que celle des simulations EM. Les méthodes développées sont tour à tour appliquées à la conception de filtres complexes qui sont réalisés en technologie microstrip / The design of microwave bandpass filter generally requires optimization or fine-tuning of the physical design parameters in order to meet the electrical specifications given by a frequency template. In this thesis we develop models to assist the designer in the time-efficient physical design of the distributed element microwave filters. The aim is to incorporate these models in different CAD methods. By a time-efficient design, we mean a design that requires a low number of EM simulations. The EM-simulations typically represent the most time-consuming step during the optimization process. We propose different modeling approaches for the frequency response behavior of the filter. The first approach models the coupling matrix as a function of the physical design parameters and the second approach models the scattering parameters, again as a function of the physical parameters. In the first part we focus on the extraction of the coupling matrix. We introduce a novel CAT technique based on an efficient estimation of the Jacobian of the function relating the design parameters to the coupling parameters. The estimation of the Jacobian uses adjoint sensitivity analysis, which drastically reduces the number of required EM-simulations. In the second part of the thesis we propose an alternative modeling approach which is based on the concept of a metamodel. The idea is that the metamodel is numerically much cheaper to evaluate than the original simulation model while keeping an acceptable accuracy. We apply these methods to several state of-the-art microstrip bandpass filters

The aim of this master’s theses was a designing of duplexer working in non license frequency band 5.6GHz. The theses is concerning with selection of suitable concept for a given duplexer, with creating a model in software for simulation of distribution of electromagnetic field and with subsequent implementation of duplexer and verifying its parameters.

This thesis deals with the analysis of coaxial cavity filters and synthesis of generic topology of these filters. Transfer function comes out the synthesis, which is based on low-pass prototype and similarity with real structure. The next aim of this thesis is to build the basic software for coaxial cavity filters synthesis from engaged characteristic parameters of the filter. This work also includes the analysis of coupling matrix synthesis based on transfer function, where we can use direct coupling or cross-coupling between resonators. The last point is focused on the diplexer filter based on specified parameters and obtained coupling matrix. Entire diplexer model is optimized using Tuning-Space Mapping method.

We reinvestigate the validity of mapping the problem of two onsite interacting particles in a random potential onto an effective random matrix model. To this end we first study numerically how the non-interacting basis is coupled by the interaction. Our results indicate that the typical coupling matrix element decreases significantly faster with increasing single-particle localization length than is assumed in the random matrix model. We further show that even for models where the dependency of the coupling matrix element on the single-particle localization length is correctly described by the corresponding random matrix model its predictions for the localization length can be qualitatively incorrect. These results indicate that the mapping of an interacting random system onto an effective random matrix model is potentially dangerous. We also discuss how Imry's block-scaling picture for two interacting particles is influenced by the above arguments.

Bandpass microwave filters are often modeled as a set of coupled discrete and localized resonators. This model is adequate in the narrow-band case. It, however, fails to describe accurately compact structures where stray couplings can be strong. To address this problem, a new view is proposed in this thesis. Instead of basing the model on localized discrete resonances, we start by constructing a model that is based on the global resonances of the structure. These are the resonances that the ports see and emerge when the entire structure is treated as a single unit. The resulting circuit, the transversal circuit, is universal. It is valid for any coupled resonator filter. The circuit is used in optimization of compact and ultra wideband suspended stripline filters and excellent results were obtained. In order to relate the global-eigen modes model to the conventional model, the issue of representation of microwave filters is investigated in detail. It is shown that a microwave filter can be represented by an infinite number of similar coupling matrices by using different modes as basis. According to this new view, a similarity transformation in microwave coupled resonator filters is interpreted as a change of basis. Two circuits that are related by a similarity transformation represent the same filter structure by using different sets of modes as basis. These conclusions were exploited in establishing a design theory for filters with dual-mode cavities. The new theory leads to direct and accurate design techniques that need no, or minimal, optimization. No tuning is used in the CAD steps. Tuning may only be required to account for manufacturing tolerances. A new tuning configuration is described and validated by computer simulation. A novel dual-mode filter with improved quality factor and reduced sensitivity is developed and designed within the same approach. The filter is fabricated and measured and excellent results are achieved. The same design methodology was used to introduce a new class of dual-mode dual-band microwave filters with improved sensitivity. It is also shown that canonical dual-mode filters can be designed within the same view with minimal local optimization of the input cavity. / Thesis (Ph.D, Electrical & Computer Engineering) -- Queen's University, 2010-03-31 01:33:36.818

Pour les systèmes de communication par satellite, des filtres avec de très bonnes performances électriques sont indispensables afin de rejeter les signaux indésirables dans de nombreuses parties de la chaîne de communication. Les technologies fort-Q peuvent répondre à cette exigence mais elles conduisent souvent à des dispositifs encombrants. D'autre part, les technologies compactes faible-Q souffrent généralement d'une dégradation des performances électriques en termes de pertes d'insertion, de sélectivité et de platitude. Pour répondre à une demande croissante concernant la réduction de la taille, il est essentiel de développer des filtres hyperfréquences compacts avec des performances électriques améliorées.Pour le filtre de réception, le défi est de concevoir un filtre passe-bande compact avec une réponse plate dans la bande passante et une forte réjection hors bande. Les pertes d'insertion ne sont pas cruciales et peuvent être compensées par un amplificateur en laissant ainsi un espace pour la conception de filtre à pertes. Un tel filtre accepte des pertes supplémentaires, qui peuvent être distribués dans le réseau afin de fournir une transmission plate dans la bande passante et une forte sélectivité hors bande.Dans le cadre de cette thèse, des nouvelles méthodes de synthèse de dispositifs de filtrage ont été étudiées et développées dans le but d’améliorer les performances tout en conservant un encombrement réduit. Ces méthodes ont été validées pour la conception de filtres de récepteur dans la charge utile de satellites de télécommunication dans le cadre d’une collaboration entre le laboratoire Xlim, le Centre National d’Etudes Spatiales et Thales Alenia Space. / For satellite communication systems, high performance filters are needed in order to reject unwanted signals in many parts of the communication chain. High quality factor (Q) technologies can meet this requirement, but they often lead to bulky devices. On the other hand, compact technologies are generally low Q and suffer from a degradation of electrical performances in terms of insertion loss, selectivity and flatness. To meet a growing demand concerning size reduction, it is essential to develop compact microwave filters with improved electrical performances.For a receive filter, the challenge is to design a compact bandpass filter with a flat response in the passband and a sharp transition in the passband edges. The insertion loss is not crucial and it can be compensated by the amplifier, leaving a room to the design of a lossy filter. Such a filter accepts additional losses, which can be distributed in the network in order to provide a flat transmission in the passband and a sharp selectivity.In this thesis, new synthesis methods for filtering devices have been studied and developed to improve performances while maintaining a small footprint. These methods have been validated for the design of filters for a receiver in payload satellites as part of collaboration between the Xlim laboratory, the France National Space Centre and Thales Alenia Space.