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High Dielectric Permittivity Materials in the Development of Resonators Suitable for Metamaterial and Passive Filter Devices at Microwave Frequencies

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High Dielectric Permittivity Materials in the Development of Resonators Suitable for Metamaterial and Passive Filter Devices at Microwave Frequencies ADVERTIMENT. Lʼaccés als continguts dʼaquesta tesi queda condicionat a lʼacceptació de les condicions dʼús establertes per la següent llicència Creative Commons: http://cat.creativecommons.org/?page_id=184 ADVERTENCIA. El acceso a los contenidos de esta tesis queda condicionado a la aceptación de las condiciones de uso establecidas por la siguiente licencia Creative Commons: http://es.creativecommons.org/blog/licencias/ WARNING. The access to the contents of this doctoral thesis it is limited to the acceptance of the use conditions set by the following Creative Commons license: https://creativecommons.org/licenses/?lang=en High dielectric permittivity materials in the development of resonators suitable for metamaterial and passive filter devices at microwave frequencies Ph.D. Thesis written by Bahareh Moradi Under the supervision of Dr. Juan Jose Garcia Garcia Bellaterra (Cerdanyola del Vallès), February 2016 Abstract Metamaterials (MTMs) represent an exciting emerging research area that promises to bring about important technological and scientific advancement in various areas such as telecommunication, radar, microelectronic, and medical imaging. The amount of research on this MTMs area has grown extremely quickly in this time. MTM structure are able to sustain strong sub-wavelength electromagnetic resonance and thus potentially applicable for component miniaturization. Miniaturization, optimization of device performance through elimination of spurious frequencies, and possibility to control filter bandwidth over wide margins are challenges of present and future communication devices. This thesis is focused on the study of both interesting subject (MTMs and miniaturization) which is new miniaturization strategies for MTMs component. Since, the dielectric resonators (DR) are new type of MTMs distinguished by small dissipative losses as well as convenient conjugation with external structures; they are suitable choice for development process. The primary advantage in using a high dielectric constant as a DR is to miniaturize the filter size. The size of DR filter is considerably smaller than the dimension of waveguide filters operate at the same frequency. For a given dielectric constant, both resonant frequency and Q-factor are defined according to the dielectric resonator dimensions. That, the higher the dielectric constant, the smaller the space within which the fields are concentrated, the lower the dimension at a defined frequency. To obtain the required compact sizes new stop-band filter is proposed in this work based on number of thick film high dielectric constant epoxy paste (TFDR) as DRs which excited with a microstrip line. In addition, a band-pass filter is proposed based on embedded dielectric resonators (EDR) constitutes a new approach to the miniaturized resonators suitable for II metamaterials design without the Q degradation inherent to the coupling coefficient based on sub-wavelength particles. Also this thesis is proposed a new band-pass filter based on split ring resonators (SRRs), which is a one of the popular MTMs building blocks today. The band-pass filters based on this concept can be very promising for the applications where miniaturization and compatibility with planar millimeter wave technology are the important issues. Also, for further miniaturization, embedded DR technology is reported. Another approach for size reduction is modifying the traditional resonator to generate additional modes, which make the resonator to behave as a multimode resonator. Finally a compact ultra-wide band-pass (UWB) band-pass filter using grounded open ring resonator as a multimode resonator (MMR) is proposed. The approach allows using five resonances to produce a 128% fractional bandwidth into the ultra-wide band. A general theoretic framework has been established using transmission matrix description of the filter constituent components. To demonstrate and validate designs functionality, all the proposed devices are implemented and fabricated, which a good agreement between simulations and measurement are obtained. Through these methods it is demonstrated that their equivalent circuit models provide an accurate description of the considered structures. Indeed, a clear relationship between their equivalents circuit model and the layout physical dimensions were found. III Resumen Los metamateriales (MTMs) representan una interesante área de investigación emergente que promete lograr un importante progreso tecnológico y científico en diversas áreas como las telecomunicaciones, la microelectrónica, radar, e imágenes médicas. La cantidad de artículos dedicados a la investigación en esta área (MTMs) se mantiene en pleno crecimiento en la actualidad. Las estructuras MTMs pueden sostener una fuerte resonancia electromagnética con longitudes de onda electricamente pequeñas y por lo tanto son potencialmente aplicables para la miniaturización de los componentes. La miniaturización, optimización del rendimiento del dispositivo mediante la eliminación de frecuencias espurias, y la posibilidad de controlar el ancho de banda del filtro para amplios márgenes de frecuencias es un reto para los presentes y futuros dispositivos de comunicación. Esta tesis se focaliza en el estudio de ambos temas (MTMs y miniaturización) centrándose en las nuevas estrategias para la miniaturización de componentes basados en MTMs. Desde la aparición de estos, los resonadores dieléctricos (DR) son un nuevo tipo de MTMs distinguidos por sus pequeñas pérdidas, así como su fácil combinación con estructuras externas; son la elección adecuada para todo proceso de desarrollo. La principal ventaja de utilizar una alta constante dieléctrica como DR es miniaturizar el tamaño del filtro. El tamaño del filtro de DR es considerablemente menor que la dimensión de la guía de ondas de otros filtros que operan a la misma frecuencia. Dada una constante dieléctrica, tanto la frecuencia de resonancia como el factor de calidad Q se definen a partir de las dimensiones del resonador dieléctrico. Cuanto mayor es la constante dieléctrica, menor es el espacio en el que se concentran los campos, y por lo tanto las dimensiones necesarias para trabajar a una frecuencia de operación definida quedan reducidas. IV Con el objetivo de miniaturizar las dimensiones del dispositivo, en este trabajo se propone un nuevo diseño para un filtro rechaza banda basado en la alta constante dieléctrica que proporciona una fina capa de pasta epoxy (TFDR) como material DRs excitado a través de una línea microstrip. Además, se propone un filtro pasa banda diseñado en base a los resonadores dieléctricos incrustados (EDR), esto constituye un nuevo enfoque en el campo de los resonadores miniaturizados adaptado a los metamateriales, logrando evitar la degradación del factor Q inherente al coeficiente de acoplamiento basado en partículas eléctricamente pequeñas. En esta tesis se propone también un nuevo filtro pasa de banda basado en resonadores de anillo dividido (SRRs), que es uno de los bloques de construcción MTMs más popular hoy en día. Los filtros de paso de banda basados en este concepto resultan prometedores para las aplicaciones donde la miniaturización y la compatibilidad con la tecnología de ondas planares milimétricas son los requisitos críticos del diseño. Además, para mayor miniaturización, tecnología DR de incrustado es reportada. Otro enfoque para la reducción de tamaño se basa en modificar el resonador tradicional para generar modos adicionales, los cuales hacen que el resonador se comporte como un resonador multimodal. Por último, se propone un filtro compacto paso banda de banda ultra ancha (UWB) utilizando un resonador de anillo abierto conectado a tierra empleado como un resonador multimodal (MMR). Esta propuesta permite utilizar cinco resonancias para producir un ancho de banda fraccional del 128% dentro de la banda ultra ancha. Para demostrar y validar la funcionalidad de los diseños, todos los dispositivos propuestos se han implementado y fabricado, con una excelente concordancia entre las simulaciones y las medidas experimentales. A través de estos métodos ha quedado demostrado que los modelos de sus circuitos equivalentes proporcionan una descripción precisa del comportamiento de las estructuras. En este trabajo se ha conseguido relacionar una relación directa entre las dimensiones físicas del dispositivo y su modelo equivalente eléctrico en forma de circuito. V Acknowledgments I would like to express my deep and sincere gratitude to my supervisor Prof. Juan Jose Garcia Garcia. I appreciate all his contributions of time, ideas and encouragements during my PhD study. It has been an honor for me to be his PhD student. I am thankful of his patience and support at every stage of this PhD work. I am very grateful for the opportunity that was given to me by Grupo de Aplicaciones Electro mangeticas Industrials (GAEMI) to carry out this work as well as for sponsoring, and the use of facilities. I thank everybody in the GAEMI group for their continuous encouragements. It is a pleasure to convey my gratitude to prof, Núria Barniol Beumala and prof, Arantxa Uranga. I would like to express my thanks to my parents for their discrete but ever so precious moral support, my sister Homa, my brother Hamidreza and also my dears Kimiya and Farhak for their great love to me and for aiding me a lot to accept and enjoy my new life conditions in Spain. Finally, I would like to special thank Meysam, my husband, for all his help and moral support. VI Contents 1 Introduction ............................................................................................................
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