Synthesis of Versatile Functionalities in Arrangements of 3D Unit-Cells

The authors would like to thank Dr. L. Le Coq and F. Boutet from IETR, for their help in the experimental activities, aswell as T. Pierré from Thales Alenia Space, for his assistance in the printing of the prototype. This work has been supported in part by the Region de Bretagne, Thales Alenia Space, Thales group through their KTD-Hardware, CNES through R&T funding, the European Union through the European Regional Development Fund, and by the Ministry of Higher Education and Research, Brittany & Rennes Metropole, through the CPER Project SOPHIE STIC & OndesThis contribution concentrates on the conception of periodic structures that are built from metallic three-dimensional unit-cells. Such arrangements allow synthesizing diverse functionalities such as polarization conversion, frequency filtering, and impedance matching. In addition, the topologies considered here can be built monolithically employing only metal, therefore providing multiple advantages, such as low insertion losses, high power handling and manufacturing certainty.Brittany & Rennes MetropoleEuropean CommissionCentre National d’Etudes SpatialesMinistère de l'Education Nationale, de l'Enseignement Superieur et de la RechercheEuropean Regional Development Fun

Methodology for Improving Scanning Performance Loading an Array Element with a 3D All-Metal WAIM

All-metal 3D printing technologies are allowing the conception of new structures for different applications. This publication explores the potential of employing for the first time an all-metal 3D unit-cell topology to perform wide-angle impedance matching layers. A new equivalent circuit is derived for the oblique incidence, providing a good estimation of the cell response for the scanning range (theta = [0 degrees, 55 degrees]) in the main scanning planes for a linearly polarized radiated field. This analytical model is later used to develop a wide-angle impedance matching design methodology for a generic antenna. This methodology is tested in practice to match a phased array made of metallic horns at 18 GHz. An improvement of 5 dB is obtained in the simulations for angles theta > 35 degrees for the H -plane.European Union through the European Regional Development Fund (ERDF)french region of BrittanyConseil Departemental 35 through the CPER Project SOPHIE/STIC OndesMinistry of Higher Education & Scientific Research (MHESR)Thales GroupRegion Bretagn

Circuit modeling of periodic structures

In the present dissertation the main goal consists in the derivation of analytical circuit models for di_erent types of 1-D periodic structures by a method based on the integral equation. Thus, in Chapter 1 the techique to derive equivalent circuits is described in detail. It is applied for 1-D periodic structures, although for 2-D periodic structures it can be applied in a similar manner. Single-slit gratings and compound gratings are analyzed by using a slit-array formulation. For the derivation of the model we assume the grating to be sandwiched by two semi- in_nite dielectric susbtrates. Extensions to more complex environments are left for the following chapters. We will also present in the same chapter the strip-array formulation, which is adequate for slit gratings with large slit apertures. The obtaining of the circuits will be explained in detail, step by step, in order to see clearly the implicit physical insights. In Chapter 2 the investigation is focused on the study of the scattering response of a periodic single slit- and strip-grating under TE and TM nor- mal and oblique incidence. Their corresponding circuit models, derived in Chapter 1 assuming that the array is sandwiched by two semi-in_nite dielec- tric slabs, are now extended to account for multilayer systems. Additionally, we will also consider a pair of coupled gratings, which, under certain sym- metry conditions, can be studied from the perspective of a single grating by using an analysis based on even and odd excitations. It will be checked the excellent agreement shown by the circuit model in comparison with results provided by HFSS. In particular, the appearance of some kind of resonances such as Wood's anomaly or anomalous extraordinary transmission are well catched by the model. Finally, a discussion about the range of validity of the models is provided. In Chapter 3, the scattering response of the well-known mushroom struc- ture under TM normal and oblique incidence is analyzed in depth. The mushroom periodic structure is actually a periodic corrugated surface. Its corresponding equivalent circuit will be used not only to check the excellent performance and the reliability to reproduce complex resonant behaviors but also as an e_cient design tool. In order to corroborate this, an absorber is easily designed by _lling the corrugations with a lossy silicon dielectric. The model also incorporate modi_cations in order to account for possible ohmic losses in the metallic surfaces. At the end of the chapter a brief discussion about the performance of the model is carried out. Chapter 4 is devoted to the study of the scattering response of com- pound gratings under TM incidence. Periodic compound gratings contain more than one slit per period. The existence of two, three, or a more num- ber of slit apertures per each period and its mutual coupling introduces a new type of resonant: the so-called phase resonance. The appearance of pha- se resonance is accompanied with several phenomena whose study is quite interesting. The circuit model will provide an alternative explanation of pha- se resonance, and will allow us to undertand the associated complexity in a simple manner. The inclusion of ohmic and dielectric losses are incoporated in the model. Furthermore, it will also be checked that the model is capable to work accurately for frequencies close to the optic regime, by taking into account the properties of metals at these frequencies by the Drude model. This fact reveals that the Microwave Network Theory can be sucessfully extended to other frequency ranges under certain circumstances. Finally, Chapter 5 shows an exhaustive study about the scattering pro- perties of coupled slit gratings under TE and TM incidence. Departing from the model of a single slit grating, a _ topology is mathematically deduced to account for a pair of coupled gratings. These gratings can be geometrically di_erent and be misaligned each other, but their period must coincide. Sys- tems containing several gratings stacked will also be considered. From the circuit point of view, a stack of gratings is readily modelled by cascading their corresponding _ circuits. A brief discussion about the limits of validity of the model is also provided

Colonial scientific-medical documentary films and the legitimization of an ideal state in post-war Spain

This paper explores the role of film and medical-health practices and discourses in the building and legitimating strategies of Franco's fascist regime in Spain. The analysis of five medical-colonial documentary films produced during the 1940s explores the relationship between mass media communication practices and techno-scientific knowledge production, circulation and management processes. These films portray a non-problematic colonial space where social order is articulated through scientific-medical practices and discourses that match the regime's need to consolidate and legitimize itself while asserting the inclusion-exclusion dynamics involved in the definition of social prototypes through processes of medicalization.O artigo explora o papel de práticas e discursos em saúde e cinema na construção e legitimação das estratégias do regime fascista de Franco na Espanha. A análise de cinco documentários médicos coloniais produzidos na década de 1940 explora a relação entre as práticas de comunicação de massa e os processos de produção, circulação e administração do conhecimento técnico-científico. Tais filmes retratam um espaço colonial não problemático onde a ordem social é articulada por meio de práticas e discursos médico-científicos que atendem à necessidade de consolidar e legitimar o regime, validando a dinâmica de inclusão-exclusão envolvida na representação de protótipos sociais por meio de processos de medicalização

The struggle for meaning in Q&A sections of the Spanish press in the first third of the 20th Century. The anarchist-libertarian and bourgeois-conservative experiences

Para Gramsci las dimensiones ideológicas y culturales de la reproducción social y el cambio social son clave para entender la dinámica socio-histórica. Por eso, la teoría gramsciana nos anima a abordar el estudio de cómo se produce el cambio social a partir del entendimiento de los procesos de generación y gestión del conocimiento como prácticas comunicativas multidimensionales. Los conceptos de hegemonía y subalternidad nos ayudan a pensar y conocer la praxis que los diversos grupos sociales realizan en torno al conocimiento. De esta manera, podemos proponer una respuesta a la cuestión ¿cómo se ha conseguido históricamente la hegemonía cultural, y qué papel tiene en ello la popularización del conocimiento científico? Ahora bien, en no pocas ocasiones, se hace referencia a hegemonía, subalternidad, contrahegemonía, educación científica, conocimiento científico como categorías cerradas en vez de considerar que forman parte de los elementos que se configuran en las luchas sociales por el significado. Por el contrario, el objeto de este trabajo es comprender y explicar el uso de determinadas herramientas comunicativas y sus consecuencias en lo que Gramsci denominaría las luchas culturales, en un contexto histórico determinado. Los llamados consultorios (secciones de preguntas y respuestas) de la prensa escrita constituyen unas fuentes privilegiadas para la exploración de los procesos de generación, gestión y aplicación de conocimiento en general y de conocimiento científico-médico en particular. En ellos interactúan expertos y no-expertos, agencias epistemológicas, experiencias cotidianas, conflictos sociales, desarrollando discursos y prácticas que legitiman, cuestionan, resignifican, los legados hegemónicos y subalternos. Por ello, nos proponemos abordar desde una perspectiva relacional las semejanzas y diferencias de las secciones de preguntas y respuestas que en los años treinta de siglo XX se publicaron en la prensa española anarco-libertaria y burguesa-conservadora. El análisis comparativo de los objetivos, las formas y los contenidos de esas secciones nos ayudarán a comprender las relaciones históricas entre los ámbitos de la hegemonía y la subalternidad, poniendo en evidencia las contradicciones, los conflictos, las mediaciones y sobre todo, las resistencias, además de la reproducción ideológica y cultural. De esta forma, la teoría gramsciana ayuda a comprender la existencia de la especificidad de la producción comunicativa de los grupos sociales. Por otro lado, el análisis comparativo que realizamos nos permite no sólo preguntarnos si son útiles los conceptos gramsciano para el conocimiento histórico que nos ocupa, sino también, teniendo en cuenta las implicaciones conceptuales de los estudios empíricos, preguntarnos por la utilidad de los objetos estudiados para la teoría social gramsciana.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Libertarian movement and self-management of knowledge in the Spain of the first third of the 20th century : «Questions and answers» section (1930-1937) of the journal Estudios

Newspaper Q&A sections reflect and contribute to the social historical context in which they are published, and they may play roles as distinct as becoming a tool to sustain social arrangements or, conversely, being an instrument for social change. In a context of complex relations between experts and non-experts within the libertarian movement in Spain in the first third of the 20th century, the Q&A section («Preguntas y respuestas», 1930-1937) of the anarchist magazine Estudios (1928-1937) constitutes a particularly illustrative example of the multidimensional management of knowledge through the effective redefinition of the participation of quite different groups. In this paper, we analyze the exchange between physician Roberto Remartínez (1895-1977), the section coordinator, and its readers, and identify features of the implementation of the libertarian principles of self-management through communication practices in which experts and non-experts jointly take part

3-D Metamaterials: Trends on Applied Designs, Computational Methods and Fabrication Techniques

This work was funded in part by the Predoctoral Grant FPU18/01965 and in part by the financial support of BBVA Foundation through a project belonging to the 2021 Leonardo Grants for Researchers and Cultural Creators, BBVA Foundation. The BBVA Foundation accepts no responsibility for the opinions, statements, and contents included in the project and/or the results thereof, which are entirely the responsibility of the authors.Metamaterials are artificially engineered devices that go beyond the properties of conventional materials in nature. Metamaterials allow for the creation of negative refractive indexes; light trapping with epsilon-near-zero compounds; bandgap selection; superconductivity phenomena; non-Hermitian responses; and more generally, manipulation of the propagation of electromagnetic and acoustic waves. In the past, low computational resources and the lack of proper manufacturing techniques have limited attention towards 1-D and 2-D metamaterials. However, the true potential of metamaterials is ultimately reached in 3-D configurations, when the degrees of freedom associated with the propagating direction are fully exploited in design. This is expected to lead to a new era in the field of metamaterials, from which future high-speed and low-latency communication networks can benefit. Here, a comprehensive overview of the past, present, and future trends related to 3-D metamaterial devices is presented, focusing on efficient computational methods, innovative designs, and functional manufacturing techniques.Predoctoral Grant FPU18/01965BBVA Foundatio

Movimiento libertario y autogestión del conocimiento en la España del primer tercio del siglo XX : la sección "Preguntas y respuestas" (1930-1937) de la revista Estudios

Las secciones periodísticas de preguntas y respuestas reflejan y contribuyen a las sociedades en que se publican, y pueden desempeñar roles tan diferentes como constituirse en una herramienta para mantener la normatividad social o, por el contrario, en un instrumento para el cambio de las normas sociales. En un contexto de complejas relaciones entre expertos y no-expertos dentro del movimiento libertario en la España del primer tercio del siglo XX, la sección «Preguntas y respuestas» (1930-1937) de la revista anarquista Estudios (1928-1937) se revela como un ejemplo particularmente ilustrativo de gestión multidimensional de conocimiento a través de la redefinición efectiva de la participación de muy diferentes colectivos. En este trabajo, analizamos el intercambio entre el médico Roberto Remartínez (1895-1977), coordinador de la sección, y los lectores, e identificamos las características de la puesta en práctica del ideario libertario de autogestión a través de prácticas comunicativas en las que intervienen conjuntamente expertos y no-expertos.Newspaper Q&A sections reflect and contribute to the social historical context in which they are published, and they may play roles as distinct as becoming a tool to sustain social arrangements or, conversely, being an instrument for social change. In a context of complex relations between experts and non-experts within the libertarian movement in Spain in the first third of the 20th century, the Q&A section («Preguntas y respuestas», 1930-1937) of the anarchist magazine Estudios (1928-1937) constitutes a particularly illustrative example of the multidimensional management of knowledge through the effective redefinition of the participation of quite different groups. In this paper, we analyze the exchange between physician Roberto Remartínez (1895-1977), the section coordinator, and its readers, and identify features of the implementation of the libertarian principles of self-management through communication practices in which experts and non-experts jointly take part

Neomalthusianismo y eugenesia en un contexto de lucha por el significado en la prensa anarquista española, 1900-1936

El artículo analiza el debate sobre neomalthusianismo y eugenesia que se realizó en medios anarquistas españoles en el primer tercio del siglo pasado. Con marcos teóricos poco utilizados hasta la fecha, se aportan nuevas interpretaciones acerca de lo que supuso la utilización del término eugenesia en las revistas neomalthusianas de inspiración anarquista. Enmarcado en una "lucha por el significado", el neomalthusianismo español resignificó las ideas eugenésicas que tenían como finalidad recuperar el terreno político perdido en la iniciativa por el control individual de la sexualidad humana. Asimismo, se analiza el papel que desempeñó la estrategia de "acción directa" por parte del movimiento anarcosindicalista que consideraba las acciones emprendidas por los anarquistas individualistas como un complemento de su acción revolucionaria.This article analyzes the debate on neo-Malthusianism and eugenics in Spanish anarchist publications in the first third of the last century. Using theoretical frameworks that have been under-utilized thus far, it provides new interpretations of what the term "eugenics" meant in pro-anarchist neo-Malthusian journals. Framed within a "struggle over meaning," Spanish neo-Malthusianism re-signified eugenic ideas in an attempt to recover political ground that had been lost in the drive to promote individual control of human sexuality. This study also analyzes the role of the anarcho-syndicalist movement's "direct action" strategy, in which actions undertaken by individualist anarchists were seen as a complement to revolutionary action

Making metals transparent: A circuit model approach

Solid metal films are well known to be opaque to electromagnetic waves over a wide frequency range, from low frequency to optics. High values of the conductivity at relatively low frequencies or negative values of the permittivity at the optical regime provide the macroscopic explanation for such opacity. In the microwave range, even extremely thin metal layers (much smaller than the skin depth at the operation frequency) reflect most of the impinging electromagnetic energy, thus precluding significant transmission. However, a drastic resonant narrow-band enhancement of the transparency has recently been reported. The quasi-transparent window is opened by placing the metal film between two symmetrically arranged and closely spaced copper strip gratings. This letter proposes an analytical circuit model that yields a simple explanation to this unexpected phenomenon. The proposed approach avoids the use of lengthy numerical calculations and suggests how the transmissivity can be controlled and enhanced by manipulating the values of the electrical parameters of the associated circuit model. � 2016 Optical Society of America.Ministerio de Economía y Competitividad TEC2013-41913-PJunta de Andalucía P12-TIC-143