Microwave filters are essential components in high frequency communication systems. The features required for these devices are increasing due to the increase in frequency, caused by the saturation of the electromagnetic spectrum. Among these features, the need for low cost devices with a reduced mass and volume and the need to integrate them with the current planar technology are highlighted. In addition, it is interested to have reconfigurable devices, that is, they can adjust their frequency response, replacing the need of multiple devices. So far, metallic waveguide filters have been used, but lately Substrate Intregated Waveguide (SIW) technology has appeared, and within this family, the innovative Empty Substrate Integrated Waveguide (ESIW). ESIW technology is empty, so that, it can be filled with liquid crystal (LC). The LC is a dielectric material with variable permittivity, which makes the filter can change its center frequency and bandwidth. There are several commercial tools based on numerical methods that enable to carry out the analysis and design of these structures, but they require a very high computational time during the analysis process. This affects negatively the automated design of these structures. On the one hand, an efficient and accurate analysis tool is developed in the thesis by following a strategy that consists on dividing the device under analysis in simple building blocks: waveguides filled with dielectric material, change of medium, discontinuities between guides and dielectric discontinuities. All of them are canonical structures or sufficiently simple that can be analyzed with modal methods. The Generalized Scattering Matrix (GSM) of each block is obtained, and they are linked in cascade by using an efficient technique. The accuracy and effectiveness of this tool are checked using it to analyze multiple filters, comparing the result with a commercial software. Furthermore, an analysis about how the variation of the permittivity of the liquid crystal affects in the frequency response of the filter is made. On the other hand, a tool for designing filters for high frequency communications is developed, in order to integrate it into a Computer Aided Design (CAD) tool. To do this, the classical techniques for designing waveguide filters are followed by adapting them to the new topology under design. Different synthesis and optimization strategies are implemented. These strategies are based on the synthesis of a starting point, the segmentation of the structure under design and the hybridization of different optimization algorithms. Also, a tool for calculating the values ​​of the permittivity of the LC that allows the reconfiguration of the filter is developed. These new permittivities enable to obtain a new desired frequency response. This tool has been used to design various microwave filters on H plane, using ESIW technology filled with liquid crystal. The accuracy and the effectiveness of this tool are checked. In addition, the reconfiguration tool designed is evaluated. Finally, a study of the manufacturing aspects is done, such as how to feed the filter and the solutions to polarize the liquid crystal. Taking into account all these considerations a prototype is manufactured and measured.

[ES] En los últimos años, se ha observado un crecimiento exponencial en los nuevos sistemas de comunicaciones, entre los cuales se destacan las comunicaciones inalámbricas y espaciales. Este fenómeno ha generado un incremento significativo en los requisitos de los sistemas de radiofrecuencia. Este aumento no solo se refiere a la respuesta eléctrica de dichos sistemas, sino también a otros parámetros de importancia, tales como el peso, el coste, el volumen y la integrabilidad con otras tecnologías. Con el propósito de cumplir con estos requisitos emergentes, los circuitos integrados en substrato, específicamente los denominados Circuitos Integrados en Substrato Vacío (Empty Substrate Integrated Circuits (ESIC)), se presentan como una solución altamente prometedora. Estos circuitos son reconocidos por su bajo coste, ligereza y facilidad de integración, preservando al mismo tiempo su eficacia en términos de respuesta eléctrica. La principal ventaja de esta tecnología radica en la capacidad de incorporar tanto componentes activos como pasivos, así como antenas, utilizando el mismo substrato o combinando varios de ellos mediante procesos de fabricación planar estándar. La naturaleza vacía de estos circuitos posibilita la implementación de componentes de alto rendimiento sin comprometer las características previas. En este contexto, la presente tesis doctoral se propone como objetivo central la investigación, diseño, desarrollo y fabricación de antenas y nuevos componentes de microondas utilizando tecnologías vacías integradas en substrato, con enfoque en aplicaciones para satélites de dimensiones reducidas. La tesis abordará la exploración de nuevos componentes de microondas comúnmente presentes en las cargas útiles de satélites, tales como filtros, transiciones entre tecnologías planares, divisores, entre otros, así como antenas, tanto como elementos individuales, y en agrupaciones. Estas investigaciones se realizarán en el marco de las mencionadas tecnologías emergentes, con la finalidad de lograr un grado de miniaturización, dispositivos altamente eficientes, y de bajo perfil manteniendo sus características esenciales y obteniendo respuestas mejoradas en comparación con soluciones previamente conocidas. La combinación global de los dispositivos y antenas propuestos en la tesis doctoral abre nuevas posibilidades en las tecnologías vacías integradas en substrato, contribuyendo potencialmente a mejorar la capacidad, robustez y compacidad de los sistemas de comunicaciones emergentes. / [CA] En els darrers anys, s'ha observat un creixement exponencial en els nous sistemes de comunicació, entre els quals destaquen les comunicacions sense fils i espacials. Aquest fenomen ha generat un increment significatiu en els requisits dels sistemes de radiofreqüència. Aquest augment no només es refereix a la resposta elèctrica d'aquests sistemes, sinó també a altres paràmetres d'importància, com ara el pes, el cost, el volum i la integrabilitat amb altres tecnologies. Amb la finalitat de complir amb aquests requisits emergents, els circuits integrats en substrat, específicament els anomenats Circuits Integrats en Substrat Buit (ESiC), es presenten com una solució altament prometedora. Aquests circuits són reconeguts pel seu baix cost, lleugeresa i facilitat d'integració, alhora que preserven la seva eficàcia en termes de resposta elèctrica. La principal avantatge d'aquesta tecnologia radica en la capacitat d'incorporar tant components actius com passius, així com antenes, utilitzant el mateix substrat o combinant-ne diversos mitjançant processos de fabricació planar estàndard. La naturalesa buida d'aquests circuits possibilita la implementació de components d'alt rendiment sense comprometre les característiques prèvies. En aquest context, la present tesi doctoral es proposa com a objectiu central la investigació, disseny, desenvolupament i fabricació d'antenes i nous components de microones utilitzant tecnologies buides integrades en substrat, amb un enfocament en aplicacions per a satèl·lits de dimensions reduïdes. La tesi abordarà l'exploració de nous components de microones comuns en les càrregues útils de satèl·lits, com ara filtres, transicions entre tecnologies planars, divisors, entre altres, així com antenes, tant com a elements individuals com en agrupacions. Aquestes investigacions es duran a terme en el marc de les esmentades tecnologies emergents, amb la finalitat d'assolir un grau de miniaturització, dispositius altament eficients i de baix perfil, mantenint les seves característiques essencials i obtenint respostes millorades en comparació amb solucions prèviament conegudes. La combinació global dels dispositius i antenes proposats en la tesi doctoral obre noves possibilitats en les tecnologies buides integrades en substrat, contribuint potencialment a millorar la capacitat, robustesa i compacitat dels sistemes de comunicació emergents. / [EN] In recent years, there has been an exponential growth observed in emerging communication systems, among which wireless and space communications stand out prominently. This phenomenon has led to a significant increase in the requirements of radiofrequency systems. This escalation pertains not only to the electrical response of such systems but also extends to other critical parameters, including weight, cost, volume, and integrability with other technologies. In order to meet these emerging requirements, integrated circuits on substrate, specifically those Empty Substrate Integrated Circuits (ESIC), emerge as a highly promising solution. These circuits are acknowledged for their low cost, lightweight nature, and ease of integration, while simultaneously preserving their effectiveness in terms of electrical response. The primary advantage of this technology lies in its capability to incorporate both active and passive components, as well as antennas, utilizing the same substrate or combining multiple substrates through standard planar manufacturing processes. The empty nature of these circuits enables the implementation of high-performance components without compromising their inherent characteristics. In this context, the central objective of this doctoral thesis is to investigate, design, develop, and manufacture antennas and new microwave components using empty substrate integrated technologies, with a focus on applications for small-scale satellites. The thesis will address the exploration of new microwave components commonly found in satellite payloads, such as filters, transitions between planar technologies, dividers, among others, as well as antennas, both as individual elements and in arrays. These investigations will be conducted within the framework of the aforementioned emerging technologies, aiming to achieve a degree of miniaturization, highly efficient devices, and low profile while maintaining essential characteristics and obtaining improved responses compared to previously known solutions. The collective integration of the proposed devices and antennas in this doctoral thesis opens up new possibilities in empty substrate integrated circuits, potentially contributing to enhancing the capacity, robustness, and compactness of emerging communication systems. / Herraiz Zanón, D. (2024). Antenas y componentes de microondas para satélites de dimensiones reducidas utilizando tecnologías vacías integradas en substrato [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/204589