This thesis discusses the design, construction and testing of a highefficiency, 100 MHz, 1 kW, Class-E solid state power amplifier. The design was performed with the aid of computer simulations using electronic design software (ADS). The amplifier was constructed around Ampleon's BLF188XR LDMOS transistor in a single ended design. The results for 100 MHz operation show a power added efficiency of 82% at 1200 W pulsed power output. For operation at 102 MHz results show a power added efficiency of 86% at 1050 W pulsed power output. Measurements of the drain- and gate voltage waveforms provide validation of Class-E operation.

L'émergence depuis ces dernières années de nouvelles capacités technologiques permettant la mise en œuvre de dispositifs d'agression électromagnétique, imposent d'étudier la faisabilité de ces potentielles Armes à Energie Dirigée ÉlectroMagnétiques (AED EM). Parmi les différentes briques technologiques qui composent ces systèmes, l'aérien est l'élément déterminant de la formation du faisceau d'ondes rayonnées et nécessite donc d'être évalué. C'est dans ce contexte que le Centre de Gramat du Commissariat à l'Énergie Atomique et aux Énergies Alternatives s'est associé à la Direction Générale de l'Armement afin de proposer cette thèse réalisée en collaboration avec l'Institut d'Électronique et de Télécommunications de Rennes. Le sujet propose l'étude complète de trois solutions antennaires susceptibles d'être intégrées sur un système de type AED EM. Chaque type d'antenne répond à une problématique qui lui est propre : Il s'agit en premier lieu de réaliser une antenne fonctionnant à fréquence fixe et possédant un gain maximisé ; Dans un second temps l'étude est menée afin de concevoir et réaliser une antenne à diagramme de rayonnement variable dans un plan et stable dans l'autre plan ; Enfin une antenne large bande fonctionnant sur une octave est développée dans le but de maintenir un diagramme de rayonnement possédant des ouvertures à mi-puissance constantes. Chacune de ces études est gouvernée par deux contraintes difficiles que sont d'une part le maintien d'une tenue en puissance élevée (niveau injecté de l'ordre du kilowatt pulsé) et d'autre part un encombrement réduit en vue d'une intégration sur porteur par exemple. Chaque antenne est élaborée à l'aide d'un logiciel de calcul électromagnétique puis réalisée afin d'être validée expérimentalement. / It is true that during the last past years, High Power Microwave (HPM) weapons threat has grown up. One way to prevent from this kind of system is to study every part of it. Among them, the antenna is the element that influences the most the electromagnetic waves behavior then it has to be evaluated. This is the reason why the Centre de Gramat du Commissariat à l’Energie Atomique et aux Energies Alternatives has teamed up with the Direction Générale de l’Armement in order to propose this thesis in collaboration with the Institut d’Electronique et de Télécommunications de Rennes. The subject provides the full study of three antennas that can be integrated on an HPM weapon. Each type of antenna is developed to address a problem: The first antenna operates at a fixed frequency and is designed to provide a maximized gain; The second one is manufactured to have a variable radiation pattern in one plane and a stable radiation pattern in the other plane; Finally, a broadband antenna operating between 2 and 4 GHz is developed in order to maintain a stable radiation pattern. Each study is led by taking into consideration high input power (around 1 kW pulsed power) and also dimensional constraints in order to be integrated on a mobile device for instance. Each antenna is designed using electromagnetic software then validated by measurements.

Reconfigurable radio frequency (RF) devices are attractive for miniaturization of wireless components and systems by handling functionality of multiple distinct devices. Existing reconfiguration techniques rely on device loadings with semiconductor diodes, ferrite/ferroelectric materials, and microelectromechanical system (MEMS) switches and capacitors. However, it is well-recognized that these techniques cannot fully address important system metrics such as high efficiency, wide frequency tuning range, high power handling capability and cost. Therefore, novel alternative techniques are highly desirable to advance the state of the art in reconfigurable RF devices. The aim of this dissertation is to investigate the novel concept of microfluidically loaded reconfigurability within the context of RF antennas and imaging systems. The proposed devices operate based on continuously movable microfluidic loads consisting of metal (liquid/solid) and dielectric solutions. Microfluidics and microfabrication techniques are utilized with flexible/rigid multilayered substrates to maximize the reconfigurable loading effect on the devices and enable highly reconfigurable antennas and imaging array realizations. Specifically, a wideband frequency tunable monopole antenna is introduced by utilizing continuously movable liquid metal within the microfluidic channel as a length varying conductor. By resorting to ultra-thin channel walls, the liquid metal volume overlapping with the microstrip line feed is utilized as a non-radiating capacitive excitation point to achieve the realized 4:1 (1.29GHz – 5.17GHz) frequency tuning range. Subsequently, an alternative design that replaces liquid metal volume with a microfluidically movable metallized plate is introduced. This novel liquid-metal-free implementation alleviates the liquid metal associated drawbacks of reliability, long-term device operation, and efficiency. The antenna is shown to provide 2:1 (1.6GHz – 3.5GHz) frequency tuning range with > 87 % radiation efficient. Due to the high radiation efficiency, the antenna is also capable of handling 15 W of RF power which is 10 W more than its liquid metal counterpart. This metallized plate approach is also suitable for reconfiguration of miniature antennas, and this is demonstrated with the design/implementation of a microfluidically reconfigurable top loaded monopole antenna. It is also suitable for reconfiguration of other structures such as textile antennas – and this is demonstrated with a 0.8GHz to 1.4GHz frequency reconfigurable textile antenna realization. The last section of the dissertation introduces a novel surface imaging array realization by utilizing the microfluidically reconfigurable metallized plate as an RF read-out circuit component. Specifically, a 24 element imaging array is designed and validated to operate within 6 – 12 GHz band with subwavelength resonators to demonstrate the possibility of constructing low-cost high-resolution microwave surface imaging arrays by utilizing the microfluidics based reconfiguration techniques. The presented work emphasizes system level implementation of the proposed devices by integrating them with micropump units, controller boards, and investigating their reliability performances under higher power RF excitations.

Tandem pumping technique are traditionally adopted to develop > 3-kW continuous-wave (cw) Yb3+-doped fiber lasers, which are usually pumped by other fiber lasers at shorter wavelengths (1018 nm e.g.). Fiber lasers directly pumped by laser diodes have higher wall-plug efficiency and are more compact. Here we report two high brightness monolithic cw fiber laser sources at 1080 nm. Both lasers consist of a cw fiber laser oscillator and one laser-diode pumped double cladding fiber amplifier in the master oscillator-power amplifier configuration. One laser, using 30-mu m-core Yb3+-doped fiber as the gain medium, can produce > 5-kW average laser power with near diffraction-limited beam quality (M-2<1.8). The slope efficiency of the fiber amplifier with respect to the launched pump power reached 86.5%. The other laser utilized 50-mu m-core Yb3+-doped fiber as the gain medium and produced > 8-kW average laser power with high beam quality (M-2: similar to 4). The slope efficiency of the fiber amplifier with respect to the launched pump power reach 83%. To the best of our knowledge, this is the first detailed report for > 5-kW near-diffraction-limited and > 8-kW high-brightness monolithic fiber lasers directly pumped by laser diodes.

Radio Frequency (RF) filters are among the key components of today’s multifunctional devices and test equipment. However, the multifuctionality need significantly drives the required filter number and causes large areas to be allocated for filters. To alleviate this issue, over the recent years, reconfigurable filters have been proposed as an attractive alternative. Nevertheless, existing reconfigurable filter technologies demonstrate degraded performances in terms of loss, frequency tunability bandwidth, and power handling capability. This work investigates, for the first time, microfluidic based reconfiguration techniques for implementation of RF bandpass filters. Specifically, microfluidics is shown to provide mechanisms for achieving compact RF bandpass filters that can exhibit low loss, high power handling, and high frequency tunability. First, we present the utilization of liquid metals for realization of a frequency-agile microstrip bandpass filters consisting of broadside coupled split ring resonator (BC-SRR). In this design approach, one of the loops of the BC-SRR is realized from liquid metal to be able to microfluidically change the resonator shape and associated resonance frequency. The filter exhibits a 29% frequency tunable range from 870 MHz to 650 MHz, with insertion loss <3 >dB, over the entire frequency tuning range, for a fractional bandwidth (FBW) of 5%. To the best of our knowledge, this filter design is the first in available literature that shows a continuously frequency reconfigurable microfluidic RF band-pass filter. To overcome the oxidization and lower conductivity issues associated with liquid metals and enhance the frequency tuning range further, subsequently, we introduce a filter design technique in which microfluidically repositionable metallized plates are utilized within microfluidic channels with ultra-thin insulator walls. Specifically, this technique is employed to design a two pole microstrip bandpass filter where microfluidically repositionable metalized plates are used to capacitively load printed open loop resonators. To operate the filter (and control movement of multiple metalized plates) with a single bi-directional micropump unit, a strategically designed meandered microfluidic channel is implemented. The filter exhibits a 50% tuning range (from 1.5 GHz to 0.9 GHz), with an insertion loss15 W input power without the need of thick ground planes and/or heat sinks.

Comme toutes modulations multiporteuses, l'OFDM souffre d'une forte variation d'amplitudes qui se traduit par un PAPR élevé. Cette caractéristique de l'OFDM la rend très sensible aux non-linéarités de l'amplificateur de puissance. Pour faire face à cette problématique, on peut surdimensionner l'amplificateur de puissance (solution non efficace en terme de rendement énergétique), linéariser l'amplificateur via les techniques de pré-distorsions, ou réduire le PAPR du signal avant amplification. L'objectif de cette thèse s'inscrit dans cette dernière thématique et plus particulièrement sur les techniques dites d'ajout de signal.Dans cette thèse, après une étude sur l'état de l'art des techniques de réduction du PAPR et en particulier les techniques dites d'ajout de signal, nous avons développé et proposé de nouvelles techniques de réduction du PAPR. Ces contributions s'articulent principalement autour des techniques de Clipping et de la Tone Reservation. / One of the main drawbacks of the OFDM modulation scheme is its high Peak-To-Average Power variation (PAPR) which can induce poor power efficiency at the transmitter amplifier. The digital base band pre-distortion for linearisation of power amplifier and the PAPR mitigation are the most commonly used solution in order to deals with efficiency and linearisation at the high power amplifier. This thesis is focused on the PAPR mitigation solution, and particularly on the adding signal based techniques. The proposed solutions in this report are about improving the Tone Reservation method which is the most popular adding signal based technique for PAPR mitigation, and also the classical clipping method which is the most simple method (in terms of computational complexity) actually.

This Thesis examines the operation and dynamic performance of a single-stage, single-switch power factor corrector, S4 PFC, with an integrated magnetic device, IM. Also detailed isthe development and analysis of a high power light emitting diode, HP LED, power factorcorrection converter and proposed voltage regulation band control approach.The S4 PFC consists of a cascaded discontinuous current mode, DCM, boost stage anda continuous current mode, CCM, forward converter. The S4 PFC achieves a high powerfactor, low input current harmonics and a regulated voltage output, utilising a singleMOSFET. A steady-state analysis of the S4 PFC with the IM is performed, identifying theoperating boundary conditions for the DCM power factor correction stage and the CCMoutput voltage regulation stage. Integrated magnetic analysis focuses on understanding theperformance, operation and generated flux paths within the IM core, ensuring the device doesnot affect the normal operation of the converter power stage. A design method for the S4 PFCwith IM component is developed along with a cost analysis of this approach. Analysis predictsthe performance of the S4 PFC and the IM, and the theoretical work is validated by MATLABand SABER simulations and measurements of a 180 W prototype converter.It is not only the development of new topological approaches that drives theadvancement of power electronic techniques. The recent emergence of HP LEDs has led to aflurry of new application areas for these devices. A DCM buck-boost converter performs thepower factor correction and energy storage, and a cascaded boundary conduction current modebuck converter regulates the current through the LED arrays. To match the useful operatinglifetime of the HP LEDs, electrolytic capacitors are not used in the PFC converter. Analysisexamines the operation and dynamic characteristics of a PFC converter with low capacitiveenergy storage capacity and its implications on the control method. A modified regulationband control approach is proposed to ensure a high power factor, low input current harmonicsand output voltage regulation of the PFC stage. Small signal analysis describes the dynamicperformance of the PFC converter, Circle Criterion is used to determine the loop stability.Theoretical work is validated by SABER and MATLAB simulations and measurements of a180 W prototype street luminaire.

Ce travail de thèse porte sur la conception, la réalisation et l'étude physique de sources lasers de haute cohérence et de forte puissance émettant dans le proche et le moyen infrarouge. Nous nous intéressons plus particulièrement aux lasers à semiconducteur émettant par la surface en cavité externe verticale (VECSEL), l'objectif étant d'obtenir un fonctionnement laser monofréquence accordables et robustes, de forte puissance à température ambiante et en régime continu dans la gamme spectrale 2-3µm et autour de 1µm, avec des dispositifs pompés optiquement ou électriquement. Nous traitons de la conception et de la caractérisation des VECSEL, depuis l'optimisation du milieu à gain jusqu'à l'élaboration et la caractérisation de prototypes laser fonctionnels, et nous effectuons une étude approfondie des propriétés physiques de l'émission laser en terme de cohérence spatiale et temporelle. / This thesis focuses on the design, realization and physical study of high power and highly coherent laser sources emitting in the near and mid-infrared. We are particularly interested in vertical external cavity surface emitting laser (VECSEL), the aim being to obtain a robust and tunable single frequency operation with high power at room temperature in continuous wave and in the spectral range of 2-3µm and around 1µm, with optically or electrically pumped devices . We discuss the design and characterization of VECSEL, from optimization of the gain medium to the development and characterization of a functional laser prototype, and we conduct a thorough study of the physical properties of the laser emission in terms of spatial and temporal coherence.

This diploma thesis deals with the analysis and description of high power laboratory CVVOZE. In the text we can find a description of the individual elements high power laboratory stating their parameters and their analysis from the perspective of impedance. The practical concern of this work is the creation of program for calculating the adjustment burdens and creating utilities helpful for operation and interpretation of laboratory function laity and technical employees.

Nanocrystalline diamond (NCD) due its outstanding thermal, mechanical and tribological properties is an ideal candidate for MEMS/NEMS devices. NCD offers the possibility to increase the reliability and life time of RF-MEMS switches and by mitigating the problems of stiction, charge trapping, surface wear and cold welding found in traditional all metal MEMS devices. In this work, nanocrystalline diamond cantilever beams and bridges have been fabricated on a low resistive silicon substrate by using standard micromachining techniques. The diamond structures are then integrated onto alumina and aluminium nitride substrates upon which microwave transmission lines in the microstrip and coplanar waveguide (CPW) topology have been fabricated. The diamond actuators are integrated using a combined soldering and flip chip technique. The NCD bridges are thermally actuated wherein the difference in coefficient of thermal expansion between copper and diamond bends the diamond bridge thus moving the bridges to the actuated state. In the CPW topology, RF-MEMS switches and tunable planar inductors are realized using the micromachined devices. These devices are mounted on a 650 micrometer thick alumina substrate and the microwave characteristics are analyzed in the frequency range of 5-30 GHz. The switches yield a return loss of 15 dB and an insertion loss of 0.2 dB at 20GHz. An inductance ratio of 2.2 is achieved by the tunable inductors at 30 GHz. High power measurements are performed on the diamond actuators which utilize a dual actuation scheme which comprises of thermal and electrostatic actuation. The measurements are performed on the diamond actuators in the power range of 24-47 dBm for the mechanically actuated switches, and 24-40 dBm for electrically actuated switches. The measurements show an insertion loss of 0.2-03 dB in the entire power spectrum. NCD based RF-MEMS capacitive switches is also designed, fabricated and tested. The switches are fabricated on a high resistive silicon substrate and are electrostatically actuated. Small signal measurements are presented in the frequency range of 1-65 GHz. The measured insertion loss in the up-state is 1.1 dB at 50 GHz with 30 dB isolation in the down-state. Dielectric characterization is performed using the Corona-Kelvin technique and the standard I-V and C-V stress tests for nitride and diamond films. The leaky nature of the diamond films provides a potential solution to reliability issues related to dielectric charging.