A growing need for developing new multi-functional materials operating at microwave frequencies is demanding a better understanding of ferroelectric and ferrimagnetic materials and their combinations. Some of these materials exhibit tunable physical properties, giving an extra degree of freedom in the device design. New multifunctional ferroelectric and ferrimagnetic thin film structures are investigated in this dissertation research, in which dielectric and magnetic properties can separately be tuned over a certain frequency range. The materials of choice, Ba0.5Sr0.5TiO3 (BST) and BaFe12O19 (BaM), both well studied and used in many microwave applications, were prepared using rf magnetron sputtering and pulsed laser ablation. Thin-film bilayers, multilayers and composite thin films were grown on various substrates, and their underlying microstructure and crystallographic properties were analyzed and optimized. After identifying the most successful growth conditions,dielectric and magnetic properties were measured. Unusual features in magnetic hysteresis loops in both sputtered and laser ablated films grown under different conditions were observed. Microcircuits were fabricated using optical lithography and microwave properties and tunability were tested in the range 1-65 GHz.

L’objectif de ces travaux est le développement en technologie intégrée standard d’une topologiede ligne de propagation optimisée en termes de pertes, d’encombrement et de facteur de qualitéaux fréquences millimétriques. Cette topologie nommée S-CPW (Shielded CoPlanarWaveguide) utilise le phénomène d’ondes lentes afin de miniaturiser longitudinalement la ligned’un facteur compris entre 1,3 et 3,2 par rapport à des topologies classiques. Disposantégalement de faibles pertes, les lignes développées présentent un facteur de qualité élevé parfoissupérieur à 40, à 60 GHz. A partir de l’étude du champ électromagnétique dans la structure, unmodèle électrique a été développé. C’est le premier modèle dans la littérature prenant en compteles pertes dans ce type de guide d’onde. Plusieurs dispositifs passifs intégrés réalisés avec deslignes S-CPW dans différentes technologies CMOS ont été caractérisés jusqu’à 110GHz. Lacompacité et les faibles pertes d’insertion obtenues pour la mesure de filtres à stubs et dediviseurs de puissance permettent de réussir l’intégration de circuits passifs compacts entechnologie microélectronique CMOS standard aux fréquences millimétriques. / This work focuses on high-performance S-CPW (Shielded CoPlanar Waveguide) transmissionlines in classical CMOS integrated technologies for the millimeter-wave frequency band.Thanks to an important slow-wave phenomenon, the physical length of S-CPW decreases by afactor from 1.3 to 3.2 compared with classical transmission lines. Presenting also lowattenuation loss, the developed transmission lines show very high quality factor (higher than 40at 60 GHz). The precise study of the electromagnetism field leads to an electrical model forS-CPWs. This is the first model that takes the losses in this topology into account. Then, somebasic passive circuits designed with S-CPWs and characterized up to 110 GHz are presented invarious CMOS technologies. The low insertion losses and relative low surfaces of a powerdivider and a passband filter show the great interest of S-CPW to integrate compact passivecircuits in classical CMOS technologies at millimeter-wave frequencies.

The Archimedean spiral antenna is well-known for its broadband characteristics with circular polarization and has been investigated for several decades. Since their development in the late 1950's, establishing an analytical expression for the characteristics of spiral antenna has remained somewhat elusive. This has been studied qualitatively and evaluated using numerical and experimental techniques with some success, but many of these methods are not convenient in the design process since they do not impart any physical insight into the effect each design parameter has on the overall operation of the spiral antenna. This work examines the operation of spiral antennas and obtains a closed-form analytical solution by conformal mapping and transmission line model with high precision in a wide frequency band. Based on the analysis of spiral antenna, we propose two novel design processes for the stripline-fed Archimedean spiral antenna. This includes a stripline feed network integrated into one of the spiral arms and a broadband tapered impedance transformer that is conformal to the spiral topology for impedance matching the nominally-high input impedance of the spiral. A Dyson-style balun located at the center facilitates the transition between guided stripline and radiating spiral modes. Measured and simulated results for a probe-fed design operating from 2 GHz to over 20 GHz are in excellent agreements to illustrate the synthesis and performance of a demonstration antenna. The research in this work also provides the possibility to achieve conformal integration and planar structural multi-functionality for an Unmanned Air Vehicle (UAV) with band coverage across HF, UHF, and VHF. The proposed conformal mapping analysis can also be applied on periodic coplanar waveguides for integrated circuit applications.

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