927 resultados para universal serial-bus (USB) dongle antennas


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With the recent progress and rapid increase in the field of communication, the designs of antennas for small mobile terminals with enhanced radiation characteristics are acquiring great importance. Compactness, efficiency, high data rate capacity etc. are the major criteria for the new generation antennas. The challenging task of the microwave scientists and engineers is to design a compact printed radiating structure having broadband behavior along with good efficiency and enhanced gain. Printed antenna technology has received popularity among antenna scientists after the introduction of planar transmission lines in mid-seventies. When we view the antenna through a transmission line concept, the mechanism behind any electromagnetic radiator is quite simple and interesting. Any electromagnetic system with a discontinuity is radiating electromagnetic energy. The size, shape and orientation of the discontinuities control the radiation characteristics of the system such as radiation pattern, gain, polarization etc. It can be either resonant or non-resonant. This thesis deals with antennas that are developed from a class of transmission lines known as coplanar strip-CPS, a planar analogy of parallel pair transmission line. The specialty of CPS is its symmetric structure compared to other transmission lines, which makes the antenna structures developed from CPS quite simple for design and fabrication. The structural modifications on either metallic strip of CPS results in different antennas. The first part of the thesis discusses a single band and dual band design derived from open ended slot lines which are very much suitable for 2.4 and 5.2 GHz WLAN applications. The second section of the study is vectored into the development of enhanced gain dipoles. A single band dipole and a wide band enhanced gain dipole suitable for 5.2/5.8 GHZ band and imaging applications are developed and discussed. Last part of the thesis discusses the development of directional UWBs. Three different types of ultra-compact UWBs are developed and almost all the frequency domain and time domain analysis of the structures are discussed.

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A novel antenna configuration comprised of two circular microstrip antennas (CMAs) resonating in the TMtt and TM2, modes, producing radiation characteristics suitable for a mobile telephone handset, is presented. The antennas operating at the same frequency are placed back to back with a separation comparable to the thickness of a typical handset. The radiation pattern consists of a region of reduced radiation intensity, which minimizes the radiation hazards to the user

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A method for simultaneously enhancing the bandwidth and reducing the size of microstrip antennas (MSAs) using a modified ground plane (GP) has been proposed with design formulas. A combshaped truncated GP is used for this purpose. This method provides an overall compactness up to 85% for proximity-coupled MSAs in the frequency range of 900 MHz–5.5 GHz with an improvement inbandwidth up to seven times when compared with the conventional ones

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A simple approach for accurate determination of the resonant frequencies of microstrip antennas of regular geometries is developed and presented. In this approach, a generalised empirical formula for the computation of effective dielectric permittivity is given which takes into account the ratio of the fringing area to the area of the patch. A correction to the equivalent side length of an equilateral triangular patch, previously published, is modified and a new formula is given. A correction to the effective dimensions of an elliptical microstrip antenna is also carried out. Numerical results obtained for the resonant frequencies of elliptical, circular, rectangular and equilateral-triangular microstrip antennas are in good agreement with the available theoretical and experimental results reported by others. The present approach is more efficient, simpler and more accurate

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The aim of the thesis is to theoretically investigate optical/plasmonic antennas for biosensing applications. The full 3-D numerical electromagnetic simulations have been performed by using finite integration technique (FIT). The electromagnetic properties of surface plasmon polaritons (SPPs) and the localized surface plasmons (LSPs) based devices are studied for sensing purpose. The surface plasmon resonance (SPR) biosensors offer high refractive index sensitivity at a fixed wavelength but are not enough for the detection of low concentrations of molecules. It has been demonstrated that the sensitivity of SPR sensors can be increased by employing the transverse magneto-optic Kerr effect (TMOKE) in combination with SPPs. The sensor based on the phenomena of TMOKE and SPPs are known as magneto-optic SPR (MOSPR) sensors. The optimized MOSPR sensor is analyzed which provides 8 times higher sensitivity than the SPR sensor, which will be able to detect lower concentration of molecules. But, the range of the refractive index detection is limited, due to the rapid decay of the amplitude of the MOSPR-signal with the increase of the refractive indices. Whereas, LSPs based sensors can detect lower concentrations of molecules, but their sensitivity is small at a fixed wavelength. Therefore, another device configuration known as perfect plasmonic absorber (PPA) is investigated which is based on the phenomena of metal-insulator-metal (MIM) waveguide. The PPA consists of a periodic array of gold nanoparticles and a thick gold film separated by a dielectric spacer. The electromagnetic modes of the PPA system are analyzed for sensing purpose. The second order mode of the PPA at a fixed wavelength has been proposed for the first time for biosensing applications. The PPA based sensor combines the properties of the LSPR sensor and the SPR sensor, for example, it illustrates increment in sensitivity of the LSPR sensor comparable to the SPR and can detect lower concentration of molecules due to the presence of nanoparticles.

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Se trata de una propuesta didáctica dirigida a los alumnos de sexto de Primaria y que tiene como principales objetivos que los escolares se familiaricen con la obra de García Lorca, se aproximen a su dimensión humana, así como a la cultura de su tiempo. Para hacer un recorrido por la obra de García Lorca se emplea como recurso didáctico una entrevista ficticia que es contestada con opiniones recogidas a través de entrevistas, conferencias y recitales del escritor granadino. Como anexo a la unidad didáctica aparece el periódico del CP El Parque en el que se publica un artículo biográfico sobre el poeta.

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Aquest curs la reducció en un 20% del preu que els estudiants de la UdG paguen per l'abonament del bus s'ha traduït en un augment de més del 600% en la venda de títols de transport

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Portal de materiales educativos relacionados con Miguel Servet. Su principal objetivo es ofrecer un repositorio de materiales pedagógicos para el profesorado y actividades para el alumnado dedicados al humanista aragonés y acercar así a las aulas el perfil del pensador, que ofrece múltiples facetas. Los contenidos están basados en su vida y obra e incluyen datos como: biografía, artículos relacionados, actividades dirigidas, enlaces, etc. Las actividades están señaladas por colores según el nivel.

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El Cine Bus La Esperanza es un proyecto que, a través de una solución móvil, busca llevar un teatro de cine itinerante a 32 municipios del Valle del Cauca, para la exhibición gratuita de películas de cine en formato de video digital. Se trata de un bus adecuado con un teatro de cine en su interior, con capacidad para 30 personas y un mecanismo para ensamblar una pantalla en su parte exterior para funciones al aire libre. Al ser una estrategia de formación y sensibilización de públicos este proyecto lleva consigo una propuesta pedagógica con el fin de posicionar el teatro de cine como un espacio público estratégico entre la población de los municipios del Valle del Cauca.

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Esta publicación fue editada con la colaboración de la Conselleria d'Educació i Cultura del Govern de les Illes Balears y el Ajuntament d'Alaior. Contiene una presentación de Josep Portella Coll

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Resumen tomado de la publicación

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Se pretende poner al alcance de los escolares una publicación que recoge tres documentos de vital importancia sobre la regulación de la pluralidad lingüística: la ley de normalización lingüística de las Islas Baleares, la Carta europea de las lenguas regionales o minoritarias y la Declaración universal de derechos lingüísticos. Todo ello enmarcado en el Año Europeo de las Lenguas que fue 2001.