Resonant-type metamaterial transmission lines and their application to microwave device design

Recientes descubrimientos han hecho posible la creación de un nuevo tipo de materiales: los metamateriales. En sólo algunos años, el desarrollo de esta nueva rama científica ha dado lugar a numerosos descubrimientos y avances tecnológicos basados en las nuevas propiedades que exhiben estos nuevos materiales. Esta tesis recoge parte del trabajo desarrollado durante los últimos años por el grupo GEMMA y CIMITEC en la aplicación de líneas de transmisión de tipo resonante en el desarrollo de dispositivos de microondas. Su pequeño tamaño y la controlabilidad de sus propiedades eléctricas son las principales propiedades de las líneas metamaterial basadas en resonadores concentrados que posibilitan su empleo en el diseño de dispositivos de microondas de pequeñas dimensiones. Estos dispositivos son de interés especialmente en aquellas aplicaciones en las que un reducido tamaño es un requerimiento importante. No obstante, además de su reducido tamaño, dichos dispositivos pueden ofrecer mejoras en su respuesta y e incluso nuevas funcionalidades. El documento ha sido escrito como compendio de 13 artículos. Dichos artículos contienen gran parte de los resultados desarrollados durante la realización de esta tesis y se detallan en una lista más adelante. El documento se ha dividido en varias secciones dedicadas a diferentes aspectos: -En el segundo capítulo se presenta una breve introducción sobre metamaterials y materiales zurdos, incluyendo sus propiedades y sus elementos constitutivos. Se dedica una especial atención a la aplicación de dichos conceptos a estructuras planares y la síntesis de líneas de transmisión metamaterial. -El tercer capítulo trata sobre la implementación de líneas de transmission metamaterial mediante el modelo resonante, que es el empleado en este trabajo. Se presentan y estudian diferentes tipos de líneas de transmission metamaterial, con especial énfasis en las estructuras empleadas en las aplicaciones presentadas en el capítulo 4. -El cuarto capítulo se dedica a las aplicaciones de las estructuras ya presentadas al diseño de components concretos, incluyendo diferentes tipos de divisors de potencia, filtros de banda ancha y estrecha y estructuras reconfigurables basadas en materiales ferroeléctricos. -Por ultimo, el quinto capítulo incluye las conclusions y posibles futuros objetivos.Recent advances have made possible the emergence of a new kind of materials: Metamaterials. In just some years, the development of this new scientific branch has given rise to numerous discoveries and technological advances based on the new properties shown by these novel materials. The present Thesis gathers a part of the work developed during the last years in the Group GEMMA and CIMITEC in the application of resonant-type metamaterial transmission lines to the development of microwave devices. The small size and the controllability of the electrical characteristics of metamaterial transmission lines based on sub-wavelength resonators are the main properties that make possible their use in the synthesis of microwave devices with compact dimensions and exceptional features. Microwave components based on metamaterial transmission lines are, therefore, of special interest in those applications in which compactness is a critical aspect. However, besides their small size, such devices can also offer a performance improvement or even new functionalities. This document has been written as a compendium of 13 articles. The articles contain most of the results of the work developed during the realisation of this Thesis and are included in a complete list given below. The document has been divided in several sections devoted to different aspects: -The second chapter presents a brief introduction about Metamaterials and left-handed materials, including their properties and constituent elements. Special attention is paid to the application of such concepts to planar structures and the synthesis of metamaterial transmission lines. -The third chapter delves into the implementation of metamaterial transmission lines by means of the resonant approach, which is applied in this work. Different kinds of resonant-type metamaterial transmission lines are presented and studied, with special emphasis on those structures which have been employed in the devices presented in chapter 4. -The fourth chapter is devoted to the applications of the previously studied structures to the design of specific components, including different kinds of power dividers, narrow- and broad-band filters and reconfigurable structures based on ferroelectric materials. -Finally, the fifth chapter includes some conclusions and possible next goals are exposed

Microwave sensors based on resonant elements

This paper highlights interest in the implementation of microwave sensors based on resonant elements, the subject of a special issue in the journal. A classification of these sensors on the basis of the operating principle is presented, and the advantages and limitations of the different sensor types are pointed out. Finally, the paper summarizes the different contributions to the special issue

Planar microwave resonant sensors : a review and recent developments

Microwave sensors based on electrically small planar resonant elements are reviewed in this paper. By virtue of the high sensitivity of such resonators to the properties of their surrounding medium, particularly the dielectric constant and the loss factor, these sensors are of special interest (although not exclusive) for dielectric characterization of solids and liquids, and for the measurement of material composition. Several sensing strategies are presented, with special emphasis on differential-mode sensors. The main advantages and limitations of such techniques are discussed, and several prototype examples are reported, mainly including sensors for measuring the dielectric properties of solids, and sensors based on microfluidics (useful for liquid characterization and liquid composition). The proposed sensors have high potential for application in real scenarios (including industrial processes and characterization of biosamples)

An analytical method to implement high-sensitivity transmission line differential sensors for dielectric constant measurements

A simple analytical method useful to optimize the sensitivity in differential sensors based on a pair of meandered microstrip lines is presented in this paper. Sensing is based on the phase difference of the transmission coefficients of both lines, when such lines are asymmetrically loaded. The analysis provides the combination of operating frequency and line length (the main design parameters) that are necessary to obtain the maximum possible differential phase (±180°) for a given level of the differential dielectric constant (input dynamic range). The proposed sensor is useful to detect tiny defects of a sample under test (SUT) as compared to a reference (REF) sample. It can also be applied to the measurement of the complex dielectric constant of the SUT, where the real part is inferred from the differential phase, whereas the imaginary part, or the loss tangent, is derived from the modulus of the transmission coefficient of the line loaded with the SUT. It is experimentally demonstrated that the proposed device is able to detect the presence of few and small (purposely generated) defects in a commercial microwave substrate, as well as subtle variations in their density, pointing out the high achieved sensor sensitivity. Sensor validation is also carried out by determining the dielectric constant and loss tangent of commercial microwave substrate

Problematic and non-problematic engagement in Online Sexual Activities across the lifespan

During the last decade, the number of people using the Internet for sexual purposes has increased exponentially. However, most studies conducted so far have analysed Online Sexual Activity (OSA) of adolescents and young people, meaning that we have few information on how this phenomenon is expressed across the lifespan. The aim of this study was to analyse three aspects of OSA (prevalence of different OSAs, motives to engage in OSA, and excessive and problematic engagement in OSA) in a large sample of individuals in different developmental stages. A self-selected sample of 8040 individuals between 12 and 85 years old were recruited and completed an online survey. Participants were distributed into five age groups and compared (60). OSA was highly prevalent across all the developmental stages, including people older than 60 years old. Differences according to the age in the use of the Internet for sexual purposes were small-to-moderate, but we identified some age-related trends in different aspects of OSA. Finally, gender was important when it came to understanding these minor age differences. This study provides a preliminary foundation for identifying the unique characteristics of OSA across the lifespan

Comportamientos homosexuales en jóvenes heterosexuales: diferencias de género

III Jornadas de Investigación para el Alumnado de SaludIntroducción: Tradicionalmente, la sexualidad se ha construido desde una perspectiva rígida que ha dificultado su expresión y vivencia en nuestra sociedad. La orientación sexual ha sido una de las dimensiones más afectadas por una dicotomización forzada. Sin embargo, la experiencia real de las personas parece ser mucho más compleja. Método: Los participantes cumplimentaron un Cuestionario ad hoc sobre Orientación Sexual desarrollado por Salusex-Unisexsida. De la muestra total, se seleccionaron aquellos jóvenes que se autoidentificaron como heterosexuales (N=514). La edad promedio fue de 21 años (DT=2,24), siendo el 25,3% hombres y el 74,7% mujeres. Resultados: El 28,4% de mujeres y el 18,5% de hombres autoidentificados como heterosexuales siente algún tipo de atracción sexual hacia personas de su mismo sexo (p=0,016). También se observa mayor disposición de las mujeres heterosexuales a tener conductas homosexuales como besos (Hombre=43,1%, Mujer=84,1%; p=0,000), caricias (Hombre=14,6%, Mujer=39,6%; p=0,000) o recibir sexo oral (Hombre=16,9%, Mujer=25,8%; p=0,008). No obstante, no existen diferencias de género en cuanto a la realización de prácticas homosexuales, es decir, el 4,6% de hombres y el 3,6% de mujeres heterosexuales las han practicado (p=0,394). Conclusiones: Se observa cómo la sexualidad es más compleja de lo que se estimaba tradicionalmente. Los jóvenes heterosexuales, manifiestan conductas homosexuales en el plano de la atracción, la intención de conducta y la realización de la misma. En línea con otros estudios, las mujeres muestran mayor prevalencia en atracción e intención de conducta homosexual, mientras que no hay diferencias en las conductas entre hombres y mujeres.Introduction: Traditionally, sexuality has been built from a rigid perspective which has complicated its expression and experience in our society. Sexual orientation has been one of the most affected dimensions by a forced dichotomisation. Nevertheless, the real experience seems to be much more complex. Method: The participants completed an ad hoc Sexual Orientation Questionnaire, which was developed by Salusex-Unisexsida. From the overall sample we selected those young people who identified themselves as heterosexuals (N=514). The mean age was 21,0 (DT=2,24): 25,3% participants were male and 74,7% female. Results: 28,4% of women and 18,5% of men self-identified as heterosexual feel a kind of attraction towards the same sex people (p=0,016). Heterosexual women are more likely to show a homosexual behaviour such as giving kisses (Male=43,1%, Female=84,1%; p=0,000), caresses (Male=14,6%, Female=39,6%; p=0,000) or receiving oral sex (Male=16,9%, Female=25,8%; p=0,008). However, no differences by gender were found with regard to the realization of homosexual practices, that is, 4,6% of men and 3,6% of heterosexual women were involved in those practices (p=0,394). Conclusion: Sexuality is more complex than was estimated traditionally. Heterosexual young people show homosexual behaviour in different levels: the attraction, behaviour intention and realization of that behaviour. In line with previous studies, women show more prevalence in attraction and homosexual behaviour intention, whereas no differences in behaviour between men and women were found

Differential-mode to common-mode conversion detector based on rat-race hybrid couplers : analysis and application to differential sensors and comparators

Altres ajuts: M. Gil acknowledges the Universidad Politécnica de Madrid Young Researchers Support Program (VJIDOCUPM18MGB) for its suppor

Highly sensitive phase variation sensors based on step-impedance coplanar waveguide (CPW) transmission lines

Reflective-mode step-impedance transmission line based sensors for dielectric characterization of solids or liquids have been recently proposed. In this article, in order to further increase the sensitivity, the sensor is implemented in coplanar waveguide (CPW technology), and this constitutes the main novelty of this work. The sensor thus consists of a high-impedance 90° (or low-impedance 180°) open-ended sensing line cascaded to a low-impedance 90° (or high-impedance 90°) line. The output variable is the phase of the reflection coefficient, which depends on the dielectric constant of the material under test (MUT), the input variable. Placing a MUT on top of the sensing line causes a variation in the effective dielectric constant of the line, thereby modifying the phase of such line. This in turn produces a multiplicative effect on the phase of the reflection coefficient, by virtue of the step-impedance discontinuity. The main advantage of the CPW-based sensor, over other similar sensors based on microstrip technology, is the stronger dependence of the phase velocity of the sensing line with the dielectric constant of the MUT, resulting in sensitivities as high as -45.48° in one of the designed sensors. The sensor is useful for dielectric characterization of solids and liquids, and for the measurement of variables related to changes in the dielectric constant of the MUT (defect detection, material composition, etc.

Highly Sensitive Reflective-Mode Defect Detectors and Dielectric Constant Sensors Based on Open-Ended Stepped-Impedance Transmission Lines

In this paper, reflective-mode phase-variation sensors based on open-ended stepped-impedance transmission lines with optimized sensitivity for their use as defect detectors and dielectric constant sensors are reported. The sensitive part of the sensors consists of either a 90° high-impedance or a 180° low-impedance open-ended sensing line. To optimize the sensitivity, such a sensing line is cascaded to a 90° transmission line section with either low or high characteristic impedance, resulting in a stepped-impedance transmission line configuration. For validation purposes, two different sensors are designed and fabricated. One of the sensors is implemented by means of a 90° high impedance (85 Ω) open-ended sensing line cascaded to a 90° low impedance (15 Ω) transmission line section. The other sensor consists of a 180° 15-Ω open-ended sensing line cascaded to a 90° 85-Ω line. Sensitivity optimization for the measurement of dielectric constants in the vicinity of that corresponding to the Rogers RO4003C substrate (i.e., with dielectric constant 3.55) is carried out. The functionality as a defect detector is demonstrated by measuring the phase-variation in samples consisting of the uncoated Rogers RO4003C substrate (the reference sample) with arrays of holes of different densities

Phase-variation microwave sensor for permittivity measurements based on a high-impedance half-wavelength transmission line

A phase-variation microwave sensor operating in transmission and implemented by means of a high-impedance half-wavelength sensing line is reported in this paper. The sensor is useful for dielectric constant measurements and dielectric characterization of materials. By forcing the electrical length of the sensing line to be a half-wavelength when it is loaded with the so-called reference (REF) material, perfect matching is obtained regardless of the characteristic impedance of the line. This fact can be used to enhance the sensitivity for small perturbations, by merely increasing the characteristic impedance of the sensing line. An exhaustive analysis that supports such conclusion is reported in the paper. Then, two prototype sensors are designed and fabricated for validation purposes. As compared to the ordinary phase-variation permittivity sensor implemented by means of a matched ( 50-Ω) line with identical length, the sensitivity for small perturbations in the proposed sensor is 2.1 times larger. Further advantages of these sensors are low-cost, small size, implementation in planar technology, and very simple design and fabrication, derived from the fact that the sensing region is a half-wavelength transmission lin