No description available.

Yes / In this paper, a compact dielectric resonator antenna (DRA) with band-notched characteristics for ultra-wideband applications is presented. A comprehensive parametric study was carried out using CST Microwave Studio Suite TM 2011 to analyze and optimize the characteristics of the proposed antenna. Three shapes for the coupling slot were investigated. Simulation results show that the proposed DRA had a −10 dB impedance bandwidth of 23% from 9.97 GHz to 12.558 GHz, and a maximum gain of 7.23 dBi. The antenna had a notched band centered at 10.57 GHz, which increased the reflection coefficient by 23.5 dB, and reduced the gain by 6.12 dB. The optimized designs were verified by experimental tests on fabricated samples.

No description available.

Dans cette thèse, on vise deux types d'applications de l’antenne à résonateur diélectrique (DRA): 1) La réalisation d’un élément rayonnant pour un réseau phasé embarqué sur un véhicule terrestre ou un avion. Cet élément de base requiert une couverture en élévation supérieure à celle des éléments imprimés pour permettre une poursuite typique comprise entre ±70°. La couverture dans un cône large est assurée avec une bonne pureté de polarisation circulaire en alimentant l’antenne à travers deux ouvertures à fente en H orthogonales parfaitement découplées en bande X. 2) La deuxième structure est destinée à la diversité d’antennes dans le contexte des réseaux corporels embarqués ou Body Area Network (BAN). L’antenne à diversité combine une antenne fente en boucle avec un DRA ce qui permet dans un espace compact de réaliser des diagrammes de type “broadside” et “endfire” respectivement. Les alimentations considérées sont de 2 types; Soit purement planaire (microruban et coplanaire) soit mixte en combinant une alimentation coaxiale et une alimentation coplanaire. Caractéristiques principales des antennes à résonateur diélectrique (DRA): Pour répondre aux attentes des utilisateurs en termes de débit, les systèmes de communication sans fils se tournent vers des fréquences de plus en plus élevées. La conséquence de cette montée en fréquence est notamment l’augmentation des pertes au niveau des éléments conducteurs et donc une diminution de l’efficacité globale des systèmes de communication. Dans ces circonstances, les DRA offre de meilleurs résultats par rapport à d'autres familles d'antennes à base d’éléments métalliques. De plus, les DRA offrent des pertes diélectriques négligeables, elles sont peu sensibles aux variations de température et s’intègrent facilement sur des technologies de fabrication planaires / Technologies such as direct broad cast satellite system (DBSS), Geosynchronous Earth Orbit (GEO) and Low Earth Orbit (LEO) satellite communications , global positioning system (GPS), high accuracy airborne navigation system and a large variety of radar systems demand for high level of antenna performance. Similar is the requirement for upcoming land based wireless systems such as cellular and indoor communication systems that is needed some more specific and additional features added to the antenna to compensate for the deficiencies encountered in system's performance. Though metallic antennas are capable enough to fulfil all the operational requirements, however at very high frequencies and under hostile temperature conditions they are constrained to face certain limitations. To avoid these constraints the performance of Dielectric Resonator Antennas (DRAs) is evaluated and their new applications are proposed. In the thesis, two types of antenna applications are sought :-First is for tracking and satellite applications that needs a larger aperture coverage in elevation plane. This coverage is realized with a good CP purity by proposing two ports dual linearly polarized DRA working at X-band. The DRA is excited by two orthogonal H-shaped aperture slots yielding two orthogonal polarizations in the broadside direction. A common impedance bandwidth of 5.9% and input port isolation of -35 dB are obtained. The broadside radiation patterns are found to be highly symmetric and stable with cross polarization levels -15dB or better over the entire matching frequency band. The maximum measured gain is found to be 2.5dBi at 8.4 GHz.- The 2nd type of antenna is a dual pattern diversity antenna to be used in the Body Area Network (BAN) context. This antenna combines a slot loop and DRA yielding broadside and end-fire radiation patterns respectively. Based upon the feeding techniques, the DG antenna is further divided into two categories one with planar feeds and the other with non-planar feeds (slot loop excited by planar CPW but DRA excited by vertical monopole) .Both types are successfully designed and measured upon body when configured into different propagation scenarios. The non-planar feeds antenna allows wider common impedance bandwidths than the planar feeds (4.95% vs 1.5%).In both cases, a maximum value of DG=9.5dB was achieved when diversity performance tests were carried out in rich fading environments. This value is close to the one (10 dB) theoretically reached in a pure Rayleigh environment and was obtained with efficiencies of 70% and 85% for the slot loop and the DRA respectively. Therefore, we conclude that these antennas could be used on the shoulders or the chest of professional clothes (firemen, policemen, soldier) where full planar integration is not a key issue but where the communication must be efficient in harsh environments and for various gestures, positions and scenarios

Made available in DSpace on 2014-12-17T14:55:13Z (GMT). No. of bitstreams: 1 JoemiaLGMM_TESE.pdf: 3140610 bytes, checksum: 8bdf88d29c888d95e74fd24e403e60fc (MD5) Previous issue date: 2013-06-07 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / Ceramic substrates have been investigated by researchers around the world and has achieved a high interest in the scientific community, because they had high dielectric constants and excellent performance in the structures employed. Such ceramics result in miniaturized structures with dimensions well reduced and high radiation efficiency. In this work, we have used a new ceramic material called lead zinc titanate in the form of Zn0,8Pb0,2TiO3, capable of being used as a dielectric substrate in the construction of various structures of antennas. The method used in constructing the ceramic combustion synthesis was Self- Sustained High Temperature (SHS - "Self-Propagating High-Temperature Synthesis") which is defined as a process that uses highly exothermic reactions to produce various materials. Once initiated the reaction area in the reaction mixture, the heat generated is sufficient to become self-sustaining combustion in the form of a wave that propagates converting the reaction mixture into the product of interest. Were analyzed aspects of the formation of the composite Zn0,8Pb0,2TiO3 by SHS powders and characterized. The analysis consisted of determining the parameters of the reaction for the formation of the composite, as the ignition temperature and reaction mechanisms. The production of composite Zn0,8Pb0,2TiO3 by SHS performed in the laboratory, was the result of a total control of combustion temperature and after obtaining the powder began the development of ceramics. The product was obtained in the form of regular, alternating layers of porous ceramics and was obtained by uniaxial pressing. 10 The product was characterized by analysis of dilatometry, X-ray diffraction analysis and scanning electron microscopy. One of the contributions typically defined in this work is the development of a new dielectric material, nevertheless presented previously in the literature. Therefore, the structures of the antennas presented in this work consisted of new dielectric ceramics based Zn0,8Pb0,2TiO3 usually used as dielectric substrate. The materials produced were characterized in the microwave range. These are dielectrics with high relative permittivity and low loss tangent. The Ansoft HFSS, commercial program employee, using the finite element method, and was used for analysis of antennas studied in this work / Substratos cer?micos t?m sido investigados por pesquisadores de todo o mundo e tem despertado um grande interesse na comunidade cient?fica, pelo fato de apresentarem altas constantes diel?tricas e um excelente desempenho nas estruturas empregadas. Tais cer?micas resultam em estruturas miniaturizadas, com dimens?es bem reduzidas e de alta efici?ncia de radia??o. Neste trabalho, utilizou-se um novo material cer?mico, chamado de titanato de zinco chumbo, na forma de Zn0,8Pb0,2TiO3, capaz de ser utilizado como substrato diel?trico na constru??o de diversas estruturas de antenas. O m?todo utilizado na constru??o da cer?mica foi a S?ntese por Combust?o Auto-Sustentada a Alta Temperatura (SHS Self-Propagating High-Temperature Synthesis ) que ? definido como um processo que utiliza rea??es altamente exot?rmicas para produzir os mais diversos materiais. Uma vez iniciada a rea??o numa ?rea da mistura reagente, o calor gerado ? suficiente para tornar a combust?o auto-sustent?vel, na forma de uma onda que se propaga convertendo a mistura reagente no produto de interesse. Foram analisados os aspectos da forma??o do comp?sito Zn0,8Pb0,2TiO3 por SHS e os p?s obtidos, foram caracterizados. A an?lise consistiu na determina??o dos par?metros da rea??o para a forma??o do comp?sito, como a temperatura de igni??o e os mecanismos de rea??o. A produ??o do comp?sito Zn0,8Pb0,2TiO3 por SHS, realizada em laborat?rio, foi resultado de um controle total da temperatura de combust?o e ap?s a obten??o do p? 8 iniciou-se o desenvolvimento das cer?micas. O produto foi obtido na forma de camadas regulares e altern?ncia de porosidades e as cer?micas foram obtidas por prensagem uniaxial. O produto foi caracterizado atrav?s de an?lises de dilatometria, difra??o de raios-X e an?lise de microscopia de varredura eletr?nica. Uma das contribui??es principais deste trabalho foi o desenvolvimento de um novo material diel?trico, n?o obstante apresentado anteriormente na literatura. Portanto, as estruturas das antenas apresentadas neste trabalho foram constitu?das por novas cer?micas diel?tricas ? base de Zn0,8Pb0,2TiO3, geralmente utilizado como substrato diel?trico. Os materiais desenvolvidos foram caracterizados na faixa de micro-ondas. S?o substratos diel?tricos de alta permissividade relativa e baixa tangente de perda. O software comercial empregado, Ansoft HFSS, baseado no m?todo dos elementos finitos, foi utilizado na an?lise das antenas estudadas neste trabalho

New archaeological research was carried out between 2009 and 2011 by the Ministry of State for Antiquities (MSA) at central Dra’ Abu el-Naga. Joining the MSA excavation team in the field in 2009, the author has been studying the findings from this area since then. The excavation site is situated ca. 700 km south of Cairo, opposite the modern city of Luxor in Upper Egypt on the western side of the Nile. Dra\'' Abu el-Naga is the modern name of the northern area of the extended necropolis. Central Dra’ Abu el-Naga lies to the north of the causeway of queen Hatshepsut and just south of the German and Spanish concessions, overlooking the valley where a temple of Amenhotep I was once erected. The tombs are situated just below the hilltop of the middle range of the Dra’ Abu el-Naga hills Review And to reach fulfill this main objective, it was proposed in 2013 to follow these research objectives: Consequently one main objective was the recording of architecture of the new discovered tombs and the reconstruction of the original context of the objects, which formed part of their burial equipment. The overlying aim of the research is: Preparing plans of all the new tombs, and also sections and 3D views of two of the tombs as they are very complicated. To place the new tombs in their archaeological context. 2D drawings can be tricky for some people to read, but 3D model views are a universal language that anyone can understand. By using SketchUp Pro to get owners, researchers heads in the same direction.

The dielectric antenna is an interesting alternative to a metallic antenna. This is mainlydue to its low manufacturing cost and the possibility to fabricate complex antennageometry with the aid of additive manufacturing (AM). Sophisticated AM technologyprovides new degrees of freedom in shaping the outer and inner geometry of antennas.This feature can be utilized to optimize various properties of antenna, such as itsbandwidth, radiation pattern etc, while maintaining a compact geometry.This master thesis investigates the possibility of improving the bandwidth of acompact dielectric antenna by modifying its geometry. Specifically, dielectricresonator antennas (DRAs) have been considered here. In this connection, twoembedded cylindrical DRAs operating within 8 GHz-17 GHz frequency band havebeen designed and simulated using Ansys HFSS. For the first design (Design-1), abandwidth (corresponding to reflection coefficient ≤ -10dB) of approximately 63%has been obtained and the second design (Design-2) has a bandwidth (correspondingto reflection coefficient ≤ -10dB) of about 57%. However, in terms of radiationcharacteristics, the performance of Design-2 has been found to be superior comparedto Design-1, mainly due to its symmetrical geometry. Furthermore, the two designshave been compared to an existing compact rectangular embedded DRA. It has beenfound that both Design-1 and Design-2 have comparatively wider bandwidth. Withrespect to the radiation characteristics, the performance of the reference antenna andDesign-2 are similar. While, the radiation performance of the reference antenna isfound to be better than Design-1. / Dielektriska antenner är ett intressant alternativ till metalliska diton. Detta beror delspå lägre tillverkningskostnader men också, tack vare additiva tillverkningsmetoder,på grund av möjligheten att använda komplexa geometrier. De senaste årens framsteginom additiv tillverkning har öppnat upp nya möjligheter vid designen av den externaoch den inre geometrin hos dielektriska antenner. Detta kan utnyttjas till att optimeraolika aspekter hos antennen, exempelvis bandbredd och strålningsmönster, utan attpåverka de yttre måtten.Denna avhandling studerar möjligheten att förbättra bandbredden hos dielektriskaresonansantenner (DRA) genom att modifiera deras inre. Två cylindriska DRA:er,verksamma inom 8-17 GHz, har designats och simulerats i Ansys HFSS. Bandbredderom 63 % för Design-1, samt 57 % för Design-2, erhölls. Trots den första designensstörre bandbredd uppvisar Design-2 bättre strålningsegenskaper, främst avseendeantennens strålningsmönster. De simulerade antennerna har också visat sig hastörre bandbredd jämfört med en redan existerande kompakt, inbäddad DRA. Sett tillstrålningsegenskaper är prestandan hos Design-2 jämförbar med referensantennen,medan design ett uppvisar sämre prestanda.

CoordenaÃÃo de AperfeiÃoamento de Pessoal de NÃvel Superior / Com os recentes avanÃos da indÃstria de telecomunicaÃÃes se faz cada vez mais necessÃrio o desenvolvimento de matÃrias que apresentem altos valores de constante dielÃtrica, baixa perda dielÃtrica e uma boa estabilidade tÃrmica. Muitos materiais para rÃdio frequÃncia e microondas tÃm sido amplamente usados em uma variedade de aplicaÃÃes nestes segmentos. Destas aplicaÃÃes, as mais recentes tecnologias utilizam cerÃmicas com baixa temperatura de sinterizaÃÃo, materiais de baixo ponto de fusÃo, alÃm das caracterÃsticas citadas anteriormente. CerÃmicas dielÃtricas a base de Bismuto sÃo candidatas como materiais de baixa temperatura de sinterizaÃÃo e tÃm sido estudadas amplamente. Este trabalho apresenta o desenvolvimento e caracterizaÃÃo da sÃrie cerÃmica CaBi4Ti4O15 (CBT) com adiÃÃo em massa de triÃxido de bismuto, material conhecido por suas excelentes propriedades dielÃtricas, principalmente elevados valores de constante dielÃtrica. Esta sÃrie foi produzida a partir do mÃtodo cerÃmico convencional ou mÃtodo do estado sÃlido, com a utilizaÃÃo de moagem mecÃnica de alta energia e tratamento tÃrmico. ApÃs a sÃntese, foi adicionado o triÃxido de bismuto em diferentes concentraÃÃes para melhorar as caracterÃsticas elÃtricas desta matriz cerÃmica. A caracterizaÃÃo estrutural foi realizada por meio de DifraÃÃo de Raios-X com Refinamento de Rietveld. Um estudo da morfologia foi realizado atravÃs de Microscopia EletrÃnica de Varredura. Foram realizados experimentos para verificar o comportamento dielÃtrico das amostras, na regiÃo de rÃdio frequÃncia e microondas. No geral percebemos que esta matriz cerÃmica apresenta as caracterÃsticas desejÃveis para sua aplicaÃÃo na fabricaÃÃo de dispositivos eletrÃnicos como capacitores e antenas ressoadoras dielÃtricas. / With the recent advances in telecommunications industry, itâs increasingly required the development of materials which have high values of dielectric constant, low dielectric loss and a good thermal stability. Many materials for radio frequency and microwaves utilization have been largely used in a variety of applications in these segments. From these applications, the latest technology generally use ceramics with low sintering temperature, low melting point materials, in addition to the aforementioned characteristics. Dielectric ceramics based on Bismuth are candidates as low temperature sintering materials and have been studied extensively. This work presents the development and characterization of ceramic series CaBi4Ti4O15 (CBT) with addition of bismuth trioxide, which is currently known for its excellent dielectric properties, mostly by its high dielectric constant values. These series were produced by the use of conventional ceramic method or method of solid state, with the use of mechanical grinding of high energy and heat treatment. After the synthesis, was added the bismuth trioxide in different concentrations to improve the electrical characteristics of ceramic CBT. The Structural characterization was showed by X-ray Diffraction with Rietveld Refinement. A study of the morphology was accomplished by scanning electron microscopy (SEM). Experiments were performed to verify the behavior of dielectric samples, radio frequency and microwaves. In general we can realize that this ceramic standard mold presents desirable characteristics for its application in the manufacture of electronic devices such as capacitors and dielectric resonator antennas.

The development of wireless communications increases the challenges on antenna performance to improve the capability of the whole system. New fabrication technologies are emerging that not only can improve the performance of components but also provide more options for materials and geometries. One of the advanced technologies, referred to as deep X-ray lithography (XRL), can improve the performance of RF components while providing interesting opportunities for fabrication. Since this fabrication technology enables the objects of high aspect ratio (tall) structure with high accuracy, it offers RF/microwave components some unique advantages, such as higher coupling energy and compacted size. The research presented in that thesis investigates the properties of deep XRL fabricated tall microstrip transmission line and describes some important features such as characteristic impedance, attenuation, and electromagnetic field distribution. Furthermore, since most of traditional feeding structure cannot supply enough coupling energy to excite the low permittivity DRA element (εr≤10), three novel feeding schemes composed by tall microstrip line on exciting dielectric resonator antennas (DRA) with low permittivity are proposed and analyzed in this research. Both simulation and experimental measured results exhibit excellent performance. Additionally, a new simulation approach to realize Dolph-Chebyshev linear series-fed DRA arrays by using the advantages of tall microstrip line feeding structure is proposed. By using a novel T shape feeding scheme, the array exhibits wide band operation due to the low permittivity (εr=5) DRA elements and good radiation pattern due to the novel feeding structure. The tall metal transmission line feed structure and the polymer-based DRA elements could be fabricated in a common process by the deep XRL technology. This thesis firstly illustrates properties and knowledge for both DRA element and the tall transmission line. Then the three novel feeding schemes by using the tall transmission line on exciting the low permittivity DRA are proposed and one of the feeding structures, side coupling feeding, is analyzed through the simulation and experiments. Finally, the T shape feeding structure is applied into low permittivity linear DRA array design work. A novel method on designing the Dolph-Chebyshev array is proposed making the design work more efficient.

<p>Embedded plates are used to support the external attachments such as heavy piping, brackets, sprinkler systems, or other equipment in nuclear power plants. The plates are welded with deformed reinforcing bars or deformed wires and anchored to reinforced concrete walls. The ACI code (ACI 318-19/ACI 349-13) provides design equations to calculate the anchor strength in concrete under tension load. These empirical equations are based on experiments conducted on headed studs, hooked bars, headed bolts, and adhesive anchors. With the lack of experimental data and code provisions on straight deformed reinforcing bars or deformed wires used as anchors, it is believed that anchoring bars with the embedment length as per code prescribed development length will provide sufficient strength to transfer tensile forces to the concrete, ignoring other failure modes such as concrete breakout. </p> <p>In this study, eight large scale group anchor tests were performed to evaluate their concrete breakout strength as per ACI 349-13. The test specimens were made with deformed reinforcing bar anchors (DRAs) and deformed wire anchors (DWAs). The tests included the effect of different bar types, bar sizes, and anchor spacings on the breakout capacities of such connections. The mean average back-calculated effective <i>k </i>value is 33.25 for DRAs and 36.26 for DWAs. The experimental study confirms that the axial tension capacity of embedded plates anchored to concrete using deformed reinforcing bars or deformed wires can be limited by concrete breakout strength.</p>