Portable low profile antenna at X-band

An antenna which has been conceived as a portable system for satellite communications based on the recommendations ITU-R S.580-6 and ITU-R S.465-5 for small antennas, i.e., with a diameter lower than 50 wavelengths, is introduced. It is a planar and a compact structure with a size of 40×40×2 cm. The antenna is formed by an array of 256 printed elements covering a large bandwidth (14.7%) at X-Band with a VSWR of 1.4:1. The specification includes transmission (Tx) and reception (Rx) bands simultaneously. The printed antenna has a radiation pattern with a 3dB beamwidth of 5°, over a 31dBi gain, and a dual and an interchangeable circular polarization

Research activities of Spanish antenna groups

When we look at the history of electricity and electromagnetism in Spain we discover that the most important Spanish researchers are generally out of the official institutions or stable research groups until the 20th century [1] [2]. In the 20th century most of the scientific research is done in stable research institutions and universities and the most important electromagnetism research centres in Spain are located in the Faculty of Physics of the most important universities, the National Scientific Research Council (CSIC) and the School for Telecommunication Engineering created in 1923. But the greatest impulse of research in the antenna and radiowave propagation field is done after 1960 reaching the first national URSI conference in 1980. After that year, the relation between groups and the number of research groups is continuously growing and the relation to industry is also increasing. When Spain joins the European research organizations (COST, ERC...) and the European Union in 1985 the research support experience a fast growing and the participation in the European research structures. In the antenna design field, there exist some specializations although most of the groups have dome specific projects in almost all the antenna analysis and design fields. Here, we have selected the most important and characteristic area related to each of the research groups and institutions. The easiest way to classify the research work in antennas is the selection between antenna analysis, design and measurement. After that the selected frequency bands technology, the type of antennas and the related circuits can be a good criterion to describe the variety of research work and specialization between groups

La Geografía Humana. ¿Una ciencia sin núcleo?

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Primeras Jornadas de Estudio sobre la Provincia de Madrid, Diputación Provincial. Madrid, diciembre de 1979.

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Ciudad, mujer y comportamiento demográfico.

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Global dimension in engineering education : promoting global learning in Spanish universities

La iniciativa ‘Dimensión Global en los Estudios Tecnológicos’ (GDEE) es una red que pretende mejorar el conocimiento, la comprensión crítica y los valores actitudinales de los estudiantes y de los postgraduados de las universidades científicotecnológicas en relación al Desarrollo Humano Sostenible (DHS). El objetivo es promover la integración del DHS como tema transversal en el currículo, mediante la mejora de las competencias de los profesores y a través de su participación y la de los estudiantes en iniciativas relacionadas con el DHS. La iniciativa empezó como un proyecto de colaboración entre un consorcio de universidades europeas y ONGs financiado por EuropeAid. Esta contribución presenta y discute la experiencia europea GDEE, profundizando las barreras y oportunidades encontradas, centrándose especialmente en la replicabilidad potencial de esta iniciativa. Estos resultados se complementan con la caracterización y el análisis comparativo del perfil académico de una comunidad de profesores implicados en actividades promovidas por GDEE.Peer ReviewedPostprint (author's final draft

Algunos estereotipos sobre la inmigración. El ejemplo de Madrid

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Mudanças no regime de precipitações do este do município La Pampa, Argentina

The eastern area of the Province of La Pampa, Argentina lies in a transition zone between the humid temperate climate stretching east and the steppe climate stretching west. The area is very sensitive to changes in precipitation patterns, especially when changes are sudden and there is no time to take adaptive measures to cope with the impacts of climate change. In such cases, agricultural production and the balance of the environment are threatened by potential disaster. In order to determine the long-term occurrence of such phenomena, long-term annual precipitation series (1921-2009) from 14 stations in the study area were analyzed using the procedure of hydrometeorological series segmentation. The results for the study period show a succession of abrupt increases, with annual precipitation increasing by about 30%. Each increase in rainfall can be seen as a fostering factor for the expansion of crop planted area in the following years. However, in recent years, there has been an abrupt and significant decrease in precipitation with a marked return to the conditions that prevailed at the beginning of the period. Because agriculture intensified during the period of increased rainfall, the carrying capacity of the environment could be exceeded if rainfall continues to decrease over a long period of time, causing a decline in production accompanied by environmental degradation.O leste do Município de La Pampa, Argentina está em uma área de transição entre o clima temperado e úmido que estende para o leste e o clima de estepe que estende para o oeste, é muito sensível às mudanças no regime de precipitações, especialmente, quando elas ocorrem de forma abrupta, não dando o tempo necessário para levar a cabo medidas adaptativas, para evitar impactos negativos das mudanças climáticas que afetam a produção agrária e o equilíbrio ambiental. Com objetivo de estudar mudanças no regime de precipitação, foram analisadas séries anuais de precipitação (1921 - 2009) de 14 estações da área de estudo, usando uma metodologia de segmentação de séries hidrometeorológicas. Os resultados indicaram que no período de estudo, aconteceram uma sucessão de mudanças abruptas, de sinal positivo em que a precipitação anual aumentou ao redor de 30%. O incremento das precipitações pode ser considerado uma das causas que explicam a expansão da área cultivada nos anos subsequentes a esses aumentos na precipitação. Não obstante, nos últimos anos, foi observada uma mudança abrupta de sinal negativo que reduziu significativamente a precipitação com um retorno marcado para as condições que prevaleceram no início do período analisado. Devido à expansão da agricultura observada no período de incremento das chuvas e, posteriormente, a diminuição dessas chuvas durante um longo período, poderia resultar na queda da produtividade e resultar em uma deterioração ambiental.Fil: Pérez, Silvia. Universidad de Buenos Aires. Facultad de Agronomia. Departamento de Recursos Naturales y Ambiente. Cátedra de Climatología y Fenologias Agrícolas; ArgentinaFil: Sierra, Eduardo Mario. Universidad de Buenos Aires. Facultad de Agronomia. Departamento de Recursos Naturales y Ambiente. Cátedra de Climatología y Fenologias Agrícolas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario; Argentin

Bootstrap: fundamentos e introducción a sus aplicaciones

La técnica bootstrap proporciona estimaciones del error estadistico, imponiendo escasas restricciones sobre las variables aleatorias analizadas y estableciéndose como un procedimiento de caracter general, independien- temente del estadístico considerado. En este trabajo se realiza una presen- tacion de los fundamentos teóricos de la técnica bootstrap, mas desde una perspectiva divulgadora que estrictamente tedrica, ademas de realizarse un breve estudio donde se podra comparar la eficacia de la técnica frente a otras mas establecidas. Palabras clave: Bootstrap, error estadistico, remuestreo Monte Car- 10, tasa de error tip0 I, técnica percentil

3x3 Multibeam Network for a Triangular Array of Three Radiating Elements

A multibeam antenna study based on Butler network will be undertaken in this document. These antenna designs combines phase shift systems with multibeam networks to optimize multiple channel systems. The system will work at 1.7 GHz with circular polarization. Specifically, result simulations and measurements of 3 element triangular subarray will be shown. A 45 element triangular array will be formed by the subarrays. Using triangular subarrays, side lobes and crossing points are reduced