Design and characterization of new tunable devices based on liquid crystal technology for microwave applications

• Autores: Javier Torrecilla Rosell
• Directores de la Tesis: Virginia Urruchi Del Pozo (dir. tes.), José Manuel Sánchez Pena (dir. tes.)
• Lectura: En la Universidad Carlos III de Madrid ( España ) en 2015
• Idioma: inglés
• Tribunal Calificador de la Tesis: José Manuel Otón (presid.), R. Vergaz (secret.), Antigone Marino (voc.)
• Programa de doctorado: Programa de Doctorado en Ingeniería Eléctrica, Electrónica y Automática por la Universidad Carlos III de Madrid
• Materias:
  • Ciencias tecnológicas
    • Tecnología electrónica
      • Diseño de filtros
      • Dispositivos de microondas
• Enlaces
  • Tesis en acceso abierto en: e-Archivo
• Resumen

  • The PhD. Thesis work presented in this document has been made in the research group Grupo de Displays y Aplicaciones Fotónicas (GDAF) of Departamento de Tecnología Electrónica from Universidad Carlos III de Madrid. One of the most traditional GDAF research interest is the study of new devices based on liquid crystals (LC). In this specific research subject, this Thesis work has been focused, including several studies about tunable devices at microwave frequencies based on LC technology. The previous experience of the Group in this field includes the devising of some preliminary approaches related to LC tunable devices, specifically phase retarders. However, no previous systematic study similar to this was made in the scope of this research Group. The main aim of this Thesis work is, indeed, to contribute to the development of new tunable devices at microwave frequencies based on new and advanced LC mixtures with electrical properties that match the requirements at GHz bands. In particular, this work has focused on the design of passive tunable filters, due to the rich functionality of these devices in telecommunication systems at microwave frequencies. The document is structured in several parts. It begins with a revision of the different available technologies used in tunable devices at GHz frequencies. Then, the main theoretical fundamentals and concepts of passive filters, notch filters and band-pass filters, are treated. In the third chapter the general processes that are involved in the manufacturing of the devices are presented. A depth study of LC-based notch filters, using a microstrip spurline structure, is detailed in chapter 4. The different steps with the restrictions that concern the design and the characterization of the manufactured devices are presented. The optimization of the devices configurations and the prediction of the filters frequency response have been made by using commercial electromagnetic software tools. Additionally, the dielectric properties at microwave frequencies of the LC mixtures used in the different devices have been estimated. Chapter 5 is devoted to tunable LC-based band-pass filters based on microstrip dual-mode technology. In the same way, the optimization of the different filter configurations, as well as the design, simulation and measurement of the frequency response of the filters are described in this chapter. Finally, in the last chapter, the main conclusions of this Thesis work and the future research lines are presented.