In modern mobile wireless communication, Base Stations (BS) are the most important equipment to build up the mobile network. One of the key elements in BS is the RF filter, which plays a key role to secure the coverage and reliability of the BS. Especially, at Transmitter (Tx) side, the filter must have a high capability to handle the power sent from Power Amplifier (PA) to antenna in any circumstances to ensure the coverage demand. Otherwise, the breakdown will be encountered, setting the power flow in the BS system in an abnormal manner that, finally can lead to the shut down of BS or destroy the system permanently. In this project, three methods using two simulation tools to predict the power handling capability of the RF/microwave resonator which is the elementary component in the BS’s filter are proposed. Power handling tests of selected configurations corresponding to the simulations are implemented as well. In the next stage, the results from the prediction and measurement are compared. Finally, the conclusions of correlation between the prediction and measurement of microwave resonator power handling will be derived.

The ever-increasing popularity and usage of communication devices has resulted in power density becoming more demanding due to crowding of frequency spectrums and narrowing of bandwidths. Consequently, the power-handling capability of filters has emerged as an important research area. With the size and mass of filters shrinking to accommodate the needs of the latest technology, designing narrowband filters necessitates the operation of filters close to their maximum power capacities. Hence, there is an urgent need to properly measure and estimate power-handling capability in filter-based products such as satellite multiplexers and wireless diplexers. In this research, the design of filters and diplexers capable of handling higher power was investigated using modifications of available methods to predict the maximum input power that a filter can handle before breakdown. This method was utilized to improve the power-handling capability and quality factor of the conventional coaxial resonator while avoiding time-consuming EM simulations. A novel coaxial resonator configuration was proposed using this method and the performance of suggested configuration was validated by designing 2-pole filters using both conventional and novel configurations. A 4-pole chebyshev filter was also designed and realized using the proposed configuration, and a power-handling analysis utilizing HFSS was compared with that of the estimated value. A novel approach in the design procedure of coaxial diplexers was proposed that provided a faster design method using step-by-step group delay matching of EM simulation results with a diplexer equivalent circuit. A method for predicting air breakdown was also applied to the diplexers to determine maximum power-handling capability.

The ever-increasing popularity and usage of communication devices has resulted in power density becoming more demanding due to crowding of frequency spectrums and narrowing of bandwidths. Consequently, the power-handling capability of filters has emerged as an important research area. With the size and mass of filters shrinking to accommodate the needs of the latest technology, designing narrowband filters necessitates the operation of filters close to their maximum power capacities. Hence, there is an urgent need to properly measure and estimate power-handling capability in filter-based products such as satellite multiplexers and wireless diplexers. In this research, the design of filters and diplexers capable of handling higher power was investigated using modifications of available methods to predict the maximum input power that a filter can handle before breakdown. This method was utilized to improve the power-handling capability and quality factor of the conventional coaxial resonator while avoiding time-consuming EM simulations. A novel coaxial resonator configuration was proposed using this method and the performance of suggested configuration was validated by designing 2-pole filters using both conventional and novel configurations. A 4-pole chebyshev filter was also designed and realized using the proposed configuration, and a power-handling analysis utilizing HFSS was compared with that of the estimated value. A novel approach in the design procedure of coaxial diplexers was proposed that provided a faster design method using step-by-step group delay matching of EM simulation results with a diplexer equivalent circuit. A method for predicting air breakdown was also applied to the diplexers to determine maximum power-handling capability.

Various facets of direct digital manufactured (DDM) microwave packages are studied. The rippled surface inherent in fused deposition modeling (FDM) fabricated geometries is modeled in Ansoft HFSS, and its effect on the performance of microstrip transmission lines is assessed via simulation and measurement. The thermal response of DDM microstrip transmission lines is analyzed over a range of RF input powers, and linearity is confirmed over that range. Two IC packages are embedded into DDM printed circuit boards, and their performance is analyzed. The first is a low power RF switch, and the second is an RF front end device that includes a low noise amplifier (LNA) and a power amplifier (PA). The RF switch is shown to perform well, as compared to a layout designed for a Rogers 4003C microwave laminate substrate. The LNA performs within datasheet specifications. The power amplifier generates substantial heat, so a thermal management attempt is described. Finally, a capacitively loaded 6dB Wilkinson power divider is designed and fabricated using DDM techniques and materials. Its performance is analyzed and compared to simulation. The device is shown to compare favorably to a similar device fabricated on a Rogers 4003C microwave laminate using traditional printed circuit board techniques.

The recent development of the commercially viable thin film electro-acoustic technology has triggered a growing interest in the research of plate guided wave or Lamb wave components owing to their unique characteristics. In the present thesis i) an experimental study of the thin film plate resonators (FPAR) performance operating on the lowest symmetrical Lamb wave (S0) propagating in highly textured AlN membranes versus a variety of design parameters has been performed. The S0 mode is excited through an Interdigital Transducer and confined within the structure by means of reflection from metal strip gratings. Devices operating in the vicinity of the stop-band center exhibiting a Q-value of up to 3000 at a frequency around 900MHz have been demonstrated. Temperature compensation of this type of devices has been studied theoretically and successfully realized experimentally for the first time. Further, integrated circuit-compatible S0 Lamb based two-port FPAR stabilized oscillators exhibiting phase noise of -92 dBc/Hz at 1 kHz frequency offset with feasible thermal noise floor below -180 dBc/Hz have been tested under high power for a couple of weeks. More specifically, the FPARs under test have been running without any performance degradation at up to 27 dBm loop power. Further, the S0 mode was experimentally demonstrated to be highly mass and pressure sensitive as well as suitable for in-liquid operation, which together with low phase noise and high Q makes it very suitable for sensor applications; ii) research in view of FPARs operating on other types of Lamb waves as well as novel operation principles has been initiated. In this work, first results on the design, fabrication and characterization of two novel type resonators: The Zero Group Velocity Resonators (ZGVR) and The Intermode-Coupled Thin Film Plate Acoustic Resonators (IC-FPAR), exploiting new principles of operation have been successfully demonstrated. The former exploits the intrinsic zero group velocity feature of the S1 Lamb mode for certain combination of design parameters while the latter takes advantage of the intermode interaction (involving scattering) between S0 and A1 Lamb modes through specially designed metal strip gratings (couplers). Thus both type of resonators operate on principles of confining energy under IDT other than reflection.

L’objectif de ce travail est d’aborder la conception de réseaux d’adaptation d’impédance accordable (RAA) dans deux contextes bien distincts en radiofréquences : le RAA en faible signal et le RAA en fort signal.Concernant les aspects faible signal, des critères de performance de RAA ont été établis et étudiés. Une nouvelle expression générale de l’efficacité d’un RAA a été développée. Elle permet de prédire le rendement d’un RAA à partir des facteurs de qualité des composants dont on dispose dans une technologie donnée et du rapport de transformation à réaliser. Des abaques de couverture d’impédances en fonction des pertes d’insertion ont été calculés. Ils mettent en évidence les régions de couverture où le RAA apporte une amélioration à la performance du système, pour diverses topologies de RAA.Un démonstrateur sur PCB a été réalisé. Il est constitué de deux RAA, qui assurent l’adaptation simultanée d’un amplificateur de puissance sur une large plage d’impédances, comprises dans un cercle de l’abaque de Smith d’équation VSWR < 5 :1. La zone de couverture a été mesurée et présentée en fonction des pertes d’insertion, qui mettent en évidence les régions où les RAA contribuent à l’amélioration de la performance de l’amplificateur et celles où les pertes d’insertion du RAA n’arrivent pas à compenser le gain du à la réduction des coefficients de réflexion.Dans une seconde partie, la conception de RAA en fort signal a été traitée. L’objectif a été de présenter à la sortie d’un amplificateur de puissance les impédances qui optimisent son efficacité pour chaque puissance de travail. Un démonstrateur en technologie CMOS SOI 130 nm a été conçu et simulé. Il consiste en un amplificateur de puissance pour le standard WCDMA, fonctionnant à 900 MHz, et un RA accordable par des varactors MOS, capable de générer les impédances optimales correspondant à des puissances de sortie comprises entre 20 et 30 dBm. Les résultats ont mis en évidence le bénéfice apporté par l’insertion d’un RA accordable par rapport à un RA fixe. / The aim of this research was the design of tunable matching networks, in two different contexts: the TMN at low and high signals.Performance criteria of TMN were studied. A general expression has been developed that estimates the TMN efficiency in function of the quality factor of the components used. The impedance coverage of different RAA topologies was plotted in function of the insertion losses.For the small signal, we designed a prototype in PCB, composed by two TMN, which ensure the simultaneous matching of a power amplifier in a wide range of impedances, included in a circle of the Smith chart VSWR < 5: 1. The coverage area was measured and presented in function of the insertion losses, emphasizing the areas where the TMN contribute to improve the amplifier performance and those where insertion losses of the TMN are not able to compensate gain with the reduction of the reflection coefficients.Subsequently, we discussed the design of TMN for the large signal. The objective is to present at the output of a power amplifier, the impedances that optimize efficiency for each power of operation. A 130 nm SOI prototype was designed and simulated, consisting of a power amplifier for WCDMA standard, 900 MHz, and a MN tunable by MOS varactors able to produce the optimal impedances corresponding to an output power between 20 and 30 dBm. The results showed the benefit provided by inserting a tunable MN compared to a fixed one.

Wireless and mobile communications are already playing an important role in our lives, and this will can only grow more and more due to the predominant importance and use of modern smartphones, tablets and any kind of connected devices. With this is mind, the spectrum for wireless and mobile communications is becoming incredibly overcrowded, leading to increasing requirements for RF front-end filters. This progress has encouraged an impressive need for developing low-cost, high performance, mass-producible, small footprint, and highly integrated front-end solutions for microwave and millimeter-wave systems and applications including emerging 5G and future wireless platforms. In this context, high quality factor resonators are usually typical basic building blocks of many high performance passive and active circuits, and its design has become even more challenging in the last decade. As a result, Substrate Integrated Waveguide (SIW) technology has attracted scientific community and industry attention as a very good candidate for developing such desired high-Q planar microwave devices. Recently, SIW is demonstrating to be a successful approach for implementing microwave and mm-wave filters with high Q-factor, easy integration with other planar circuits, and for mass-production manufacturing processes in many technologies (i.e. Printed Circuit Board (PCB) and Low Temperature Co-fired Ceramics (LTCC) technologies among them). Its enormous similarity with waveguides is probably one of the main reasons why the development of SIW-based components and circuits is rapidly growing among the research community. Other potential features that, combined with the former advantages, could be of huge interest in a wide range of wireless and mobile applications are a lively set of research subjects, such as compactness, advanced filtering responses, and recently frequency-agility capabilities. These key features have been recently introduced in the design of microwave filters for the next-generation wireless systems. Taking into account the above-mentioned background, the work carried out during the course of this PhD Thesis has been directed towards a further study of SIW technology to propose, analyze and develop an innovative and original resonator topology. The proposed topology is based on the extension of the classical coaxial waveguide resonator to SIW technology, and must take advantage of the characteristics of SIW devices to allow the design of improved and innovative microwave resonator filters for advanced wireless systems. This PhD Thesis includes the latest improvements made on this topic, from the working principles of the basic coaxial SIW block, until different applications for the design of compact quasi-elliptic and reconfigurable microwave filters. The results are promising and demonstrate the validity of the proposed topology for the design of high-Q microwave filters, as well as its potential application to implement complex designs. The general knowledge gained from these cases of study can be considered a good base for further developing this technology, which can help to improve its EM performance, and also contribute to a more general use in the market. / Las comunicaciones inalámbricas y móviles juegan un papel importante en nuestras vidas, y esto sólo puede ir a más debido a su enorme importancia y al uso de los modernos teléfonos inteligentes (del inglés, smartphones), tabletas y toda clase de dispositivos inalámbricos. Con todo esto en mente, el espectro electromagnético para comunicaciones inalámbricas y móviles se está saturando cada día más, lo que conlleva un constante aumento de los requisitos para los filtros de radio-frecuencia usados en las cabeceras de dichos sistemas. Este progreso ha llevado a un creciente interés en desarrollar componentes de microondas de bajo coste, alto rendimiento, pequeño tamaño, que permitan implementar soluciones altamente integradas para sistemas de alta frecuencia (i.e. microondas y ondas milimétrica) y sus aplicaciones, incluyendo entre ellas la emergente conexión 5G y las futuras plataformas inalámbricas. En este contexto, los resonadores de elevado factor de calidad constituyen generalmente los bloques básicos para el diseño de muchos circuitos pasivos (entre ellos filtros) y activos de alto rendimiento. Su diseño se ha convertido por tanto en un reto aún mayor en la última década. Como resultado de ello, la tecnología de guía de ondas integradas en substrato (Substrate Integrated Waveguide, SIW) ha atraído la atención de la comunidad científica e industrial, al revelarse como una buena aproximación para el desarrollo de dispositivos planares de microondas con excelentes prestaciones eléctricas, y en particular para la implementación de filtros de microondas y onda milimétrica de bajas pérdidas y elevada integración con circuitos en tecnología planar. Además, su flexibilidad se caracteriza también por su adecuación a diferentes procesos de fabricación y producción en masa, en tecnologías tales como los circuitos impresos (Printed Circuit Board, PCB) o la tecnología de materiales cerámicos multi-capa co-sinterizados a baja temperatura (Low Temperature Co-fired Ceramics, LTCC) entre otras. Su enorme similitud con las ya largamente estudiadas guías de onda es, probablemente, una de las principales razones por las cuales el desarrollo de dicho circuitos está creciendo rápidamente entre la comunidad de investigadores. Cabe mencionar como, además de las anteriores ventajas, otras características de la tecnología SIW que podrían ser de gran interés en una amplia gama de aplicaciones inalámbricas y móviles son la miniaturización, la posibilidad de implementar respuestas avanzadas de filtrado y, recientemente, las capacidades de sintonía en frecuencia de los componentes de microondas. De este modo, el trabajo desarrollado a lo largo de esta Tesis Doctoral se ha orientado hacia el planteamiento, análisis y desarrollo de una topología de resonador innovadora y original. Dicha topología se basa en una extensión de las cavidades coaxiales en guía de onda metálica a una implementación integrada en substrato inspirada en la tecnología SIW. Esta Tesis Doctoral recapitula los últimos avances que se han producido sobre este tema, empezando desde la descripción de los principios fundamentales de funcionamiento de las estructuras, hasta la demostración de varias aplicaciones concretas útiles para el diseño de filtros de microondas muy compactos, con respuestas filtrantes avanzadas y reconfigurables. Los resultados que se van a mostrar a continuación son prometedores, y demuestran la validez de la topología propuesta. El conocimiento general obtenido de los diferentes prototipos fabricados y caracterizados experimentalmente puede considerarse una buena base para seguir desarrollando esta tecnología, lo que puede ayudar a mejorar su rendimiento electromagnético, así como a contribuir a un uso más extendido de estos dispositivos en el mercado. / Les comunicacions sense fils i mòbils juguen un paper important en les nostres vides, i això només pot anar a més a causa de la gran importància i l'ús dels moderns telèfons intel·ligents (de l'anglès, smartphones), tablets i tota classe de dispositius sense fil. Tenint en compte tot açò, l'espectre electromagnètic per a comunicacions sense fils i mòbils s'està saturant cada dia més, el que comporta un constant augment dels requisits per als filtres de radiofreqüència usats en les capçaleres d'aquests sistemes. Aquest progrés ha portat a un creixent interès en desenvolupar components de microones de baix cost, alt rendiment, volum reduït, que permeten implementar solucions altament integrades per a sistemes d'alta freqüència (ie. microones i ones mil·limètriques) i les seves aplicacions, incloent l'emergent connexió 5G i les futures plataformes sense fils. En aquest context, els ressonadors d'elevat factor de qualitat constitueixen generalment els blocs bàsics per al disseny de molts circuits passius (entre ells filtres) i actius d'alt rendiment. El seu disseny s'ha convertit per tant en un repte encara més gran en l'última dècada. Com a resultat d'això, la tecnologia de guia d'ones integrades en substrat (Substrate Integrated Waveguide, SIW) ha atret l'atenció de la comunitat científica i industrial, al revelar-se com una bona aproximació per al desenvolupament de dispositius planars de microones amb excel·lents prestacions elèctriques , i en particular per a la implementació de filtres de microones i ones mil·limètriques de baixes pèrdues i elevada integració amb circuits en tecnologia planar. A més, la seua flexibilitat es caracteritza també per la seua adequació a diferents processos de fabricació i producció en massa, en tecnologies com ara els circuits impresos (Printed Circuit Board, PCB) o la tecnologia de materials ceràmics multicapa co-sinteritzats a baixa temperatura (Low Temperature Co-Fired Ceramics, LTCC) entre d'altres. La seua enorme similitud amb les ja llargament estudiades guies d'ona és, probablement, una de les principals raons per les quals el desenvolupament d'aquests circuits està creixent ràpidament entre la comunitat d'investigadors. Cal destacar com, a més de les anteriors avantatges, altres característiques de la tecnologia SIW que podrien ser de gran interès en una àmplia gamma d'aplicacions sense fils i mòbils són la miniaturització, la possibilitat d'implementar respostes avançades de filtrat i, recentment, les capacitats de sintonia en freqüència dels components de microones. Aquestes característiques clau s'han introduït recentment en el disseny de filtres microones per als sistemes sense fils de pròxima generació, convertint-se en objecte prioritari d'estudi per part de la comunitat científica. D'aquesta manera, el treball desenvolupat al llarg d'aquesta tesi doctoral s'ha orientat cap al plantejament, anàlisi i desenvolupament d'una topologia de ressonador innovadora i original. Aquesta topologia es basa en una extensió de les cavitats coaxials en guia d'ona metàl·lica a una implementació integrada a substrat inspirada en la tecnologia SIW. Aquesta tesi doctoral recapitula els últims avanços que s'han produït sobre aquest tema, començant des de la descripció dels principis fonamentals de funcionament de les estructures, fins a la demostració de diverses aplicacions concretes útils per al disseny de filtres i microones molt compactes, amb respostes de filtrat avançades i reconfigurables. Els resultats que es mostraran a continuació són prometedors, i demostren la validesa de la topologia proposada. El coneixement general obtingut dels diferents prototips fabricats i caracteritzats experimentalment es pot considerar com una bona base per seguir desenvolupant aquesta tecnologia, el que pot ajudar a millorar el seu rendiment electromagnètic, així com a contribuir a un ús més estès d'aquests dispositius en el mer / Sirci, S. (2017). Substrate Integrated Coaxial Filters with Fixed and Tunable Responses [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/78838 / TESIS

Over the last few years, the ever-increasing use of the new emerging wireless communication systems has imposed a considerable challenge in the development of novel microwave devices that can support the high bit rates and wide bandwidths demanded by the society. Moreover, other of the main goals of the current microwave components' designers is the fact that these devices can withstand the increasingly higher RF power requirements that must be considered at the output stages of transmitters. In this context, several physical phenomena should be analyzed in order to maximize the so-called power handling capability (PHC) in microwave components. In particular, this thesis focuses on the study of the corona discharge breakdown, since it is a physical effect that may limit the peak power thresholds (also known as peak power handling capability or PPHC) of microwave devices. In this regard, the main aim of this work is the proposal of several design strategies to achieve a considerable improvement of the PPHC in different filtering structures. In this sense, this dissertation is divided into two main parts. On the one hand, the study of the corona discharge breakdown will be first focused on microstrip bandpass filters, where the variation of the maximum electric field strength will be analyzed, and different solutions based on dielectric covers, rounded open-circuit terminations, an anticorona lacquer or a commercial adhesive will be thoroughly investigated and compared. The main objective will be the maximization of the peak power levels, while the degradation of the unloaded quality factor of the resonators will be minimized as far as possible. On the other hand, the second part of this thesis dissertation deals with a similar exhaustively analysis in groove gap waveguides (GGWs). Furthermore, different topologies of bandpass filters based on this technology will be studied, focusing also on the type of the electric field's polarization. In a similar way, several design criteria will be proposed for improving the PPHC of these components, thereby achieving a significant enhancement and reaching the same peak power thresholds of the counterpart rectangular waveguide devices. Finally, all the solutions described above will be experimentally validated in diverse measurement campaigns carried out at the European High Power RF Space Laboratory to corroborate the proper and good performances of all of them. / A lo largo de los últimos años, el uso cada vez mayor de los nuevos sistemas de comunicación inalámbricos emergentes ha impuesto un reto considerable en el desarrollo de novedosos dispositivos de microondas que puedan soportar las altas tasas de bits y amplios anchos de banda demandados por la sociedad. Además, otro de los principales objetivos de los actuales diseñadores de componentes de microondas es el hecho de que estos dispositivos puedan soportar los requisitos de potencia RF cada vez más elevados que se deben considerar en las etapas de salida de los transmisores. En este contexto, diversos fenómenos físicos deben ser estudiados para maximizar la denominada capacidad de manejo de potencia (PHC, por sus siglas en inglés) en componentes de microondas. En particular, esta tesis doctoral se centra en el estudio de la descarga de corona, ya que es un efecto físico que puede limitar los umbrales de potencia de pico (también conocido como capacidad de manejo de la potencia de pico o PPHC, por sus siglas en inglés) de dispositivos de microondas. Por ello, el principal objetivo de este trabajo es la propuesta de varias estrategias de diseño para conseguir una mejora considerable de la PPHC en diferentes estructuras filtrantes. En este sentido, esta tesis se divide en dos partes principales. Por un lado, el estudio del efecto corona se centrará en primer lugar en filtros paso banda en tecnología microstrip, donde se analizará la variación de la intensidad máxima del campo eléctrico, así como también se investigarán y compararán a fondo diferentes soluciones basadas en cubiertas dieléctricas, terminaciones en circuito abierto redondeadas, una laca anticorona o un adhesivo comercial. El objetivo principal será maximizar los niveles de potencia de pico, mientras se minimizará en la medida de lo posible la degradación del factor de calidad de los resonadores. Por otro lado, la segunda parte de esta tesis doctoral aborda un análisis exhaustivo parecido en guías de onda groove-gap (GGWs, por sus siglas en inglés). Además, se estudiarán distintas topologías de filtros paso banda basados en esta tecnología, centrándose también en el tipo de polarización del campo eléctrico. Del mismo modo, se propondrán varios criterios de diseño para mejorar la PPHC de estos componentes, consiguiendo así una mejora significativa y alcanzando los mismos umbrales de potencia de pico que los dispositivos equivalentes en guía de onda rectangular. Finalmente, todas las soluciones descritas serán validadas experimentalmente en diversas campañas de medidas realizadas en el Laboratorio Europeo de Alta Potencia en RF para corroborar el correcto y buen funcionamiento de todas ellas. / Al llarg dels últims anys, l'ús cada vegada major dels nous sistemes de comunicació sense fils emergents ha imposat un repte considerable en el desenvolupament de nous dispositius de microones que puguen suportar les altes taxes de bits i grans amplades de banda demandades per la societat. A més, un altre dels principals objectius dels actuals dissenyadors de components de microones és el fet que aquests dispositius puguen suportar els requisits de potència RF cada vegada més elevats que s'han de considerar en les etapes d'eixida dels transmissors. En aquest context, diversos fenòmens físics han de ser estudiats per a maximitzar la denominada capacitat de maneig de potència (PHC, per les seues sigles en anglès) en components de microones. En particular, aquesta tesi doctoral se centra en l'estudi de la descàrrega de corona, ja que és un efecte físic que pot limitar els llindars de potència de pic (també conegut com a capacitat de maneig de la potència de pic o PPHC, per les seues sigles en anglès) de dispositius de microones. Per això, el principal objectiu d'aquest treball és la proposta de diverses estratègies de disseny per a aconseguir una millora considerable de la PPHC en diferents estructures filtrants. En aquest sentit, aquesta tesi es divideix en dues parts principals. Per un costat, l'estudi de l'efecte corona se centrarà en primer lloc en filtres passabanda en tecnologia microstrip, on s'analitzarà la variació de la intensitat màxima del camp elèctric, així com també s'investigaran i compararan a fons diferents solucions basades en cobertes dielèctriques, terminacions en circuit obert arredonides, una laca anticorona o un adhesiu comercial. L'objectiu principal serà maximitzar els nivells de potència de pic, mentre es minimitzarà en la mesura que siga possible la degradació del factor de qualitat dels ressonadors. Per l'altre costat, la segona part d'aquesta tesi doctoral aborda una anàlisi exhaustiva similar en guies d'ona groove-gap (GGWs, per les seues sigles en anglès). A més, s'estudiaran diferents topologies de filtres passabanda basats en aquesta tecnologia, centrant-se també en el tipus de polarització del camp elèctric. De la mateixa manera, es proposaran diversos criteris de disseny per a millorar la PPHC d'aquests components, aconseguint així una millora significativa i els mateixos llindars de potència de pic que els dispositius equivalents en guia d'ona rectangular. Finalment, totes les solucions descrites seran validades experimentalment en diverses campanyes de mesures realitzades en el Laboratori Europeu d'Alta Potència en RF per a corroborar el correcte i bon funcionament de totes elles. / Work supported by the Spanish Ministry of Science and Innovation (MCIN) and the State Agency of Research (AEI) through the Sub-Project C43 of the Coordinated Project PID2019-103982RB [MCIN/AEI/10.13039/501100011033]. Aitor Morales-Hernández has received a fellowship grant from the University of Alicante [UAFPU2018-054].

This thesis presents the RF and mechanical design of a metal-to-metal contact RF MEMS switch. Metal-to-metal contact RF MEMS switches are especially preferred in low frequency bands where capacitive switches suffer from isolation due to the limited reactance. Frequency band of operation of the designed switch is from DC to beyond X-band. Measured insertion loss of the structure is less than 0.2 dB, return loss is better than 30 dB, and isolation is better than 20 dB up to 20 GHz. Isolation is greater than 25 dB below 10 GHz. Hence, for wideband applications, this switch offers very low loss and high isolation. Time domain measurement is necessary for the investigation of the dynamic behavior of the devices, determination of the &lsquo / pull in&rsquo / and &lsquo / pull out&rsquo / voltages of the membranes, switching time and power handling of the devices. Also, failure and degradation of the switches can be monitored using the time domain setup. For these purposes a time domain setup is constructed. Moreover, failure mechanisms of the RF MEMS devices are investigated and a power electronic circuitry is constructed for the biasing of RF MEMS switches. Advantage of the biasing circuitry over the direct DC biasing is the multi-shape, high voltage output waveform capability. Lifetimes of the RF MEMS devices are investigated under different bias configurations. Finally, for measurement of complicated RF MEMS structures composed of large number of switches, a bias waveform distribution network is constructed where conventional systems are not adequate because of the high voltage levels. By this way, the necessary instrumentation is completed for controlling a large scale RF MEMS system.

<div>In recent years, intelligent devices such as smartphones and self-driving cars are becoming ubiquitous in daily life, and thus, wireless communication is turning out to be increasingly omnipresent. To efficiently utilize the electromagnetic spectrum, automatically reconfigurable software-controlled radio transceivers are drawing an extensive amount of attention. In order to implement a reconfigurable radio transceiver, automatically tunable RF front-end components such as tunable filters are indispensable. Over the last decade, tunable filters have shown promising performance with high-quality factor (Q), a wide tuning range, and high-power handling. However, most of the existing tunable filters are manually adjusted. In this regard, this research work focuses on developing a novel automatic software-driven tuning technique for continuously tunable microwave and millimeter-wave filters.</div><div><br></div><div><br></div><div>First, a K-band continuously tunable bandpass filter has been demonstrated with contactless printed circuit board (PCB) tuners. Then, an automatic tuning technique based on deep-Q learning has been proposed and realized to tune a filter with contactless tuners automatically. Two-pole, three-pole, and four-pole bandpass filters are experimentally tested as examples without any human intervention to prove the feasibility of the tuning technique. For the first time, unlike a look-up table, the filters can be continuously tuned at a practically infinite number of frequencies inside the tuning range. </div><div><br></div><div>Next, a K/Ka-band tunable absorptive bandstop filter (ABSF) has been designed and fabricated in low-cost PCB technology. Contrary to a reflective bandstop filter, an ABSF filter is preferred for interference mitigation due to its deeper notch and lower reflection. However, the absorbed power may limit the filter's power handling. Therefore, lastly, a comparative analysis of power handling capability (PHC) between a reflective bandstop filter and an absorptive bandstop filter has been studied theoretically and experimentally in this dissertation.</div>