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Simple Excitation Model for Coaxial Driven Monopole Antennas

TRINTINALIA, Luiz C.
Fonte: IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC Publicador: IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC
Tipo: Artigo de Revista Científica
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A new excitation model for the numerical solution of field integral equation (EFIE) applied to arbitrarily shaped monopole antennas fed by coaxial lines is presented. This model yields a stable solution for the input impedance of such antennas with very low numerical complexity and without the convergence and high parasitic capacitance problems associated with the usual delta gap excitation.; Conselho Nacional de Desenvolvimento Cientifico e Tecnologico (CNPq)

Optimization and Complexity Reduction of Switch-Reconfigured Antennas Using Graph Models

COSTANTINE, Joseph; CHRISTODOULOU, Christos G.; ABDALLAH, Chaouki T.; Barbin, Silvio Ernesto
Fonte: IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC Publicador: IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC
Tipo: Artigo de Revista Científica
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This letter addresses the optimization and complexity reduction of switch-reconfigured antennas. A new optimization technique based on graph models is investigated. This technique is used to minimize the redundancy in a reconfigurable antenna structure and reduce its complexity. A graph modeling rule for switch-reconfigured antennas is proposed, and examples are presented.

Analyzing the Complexity and Reliability of Switch-Frequency-Reconfigurable Antennas Using Graph Models

Costantine, Joseph; Tawk, Youssef; Christodoulou, Christos G.; Lyke, James C.; De Flaviis, Franco; Besoli, Alfred Grau; Barbin, Silvio Ernesto
Fonte: IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC; PISCATAWAY Publicador: IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC; PISCATAWAY
Tipo: Artigo de Revista Científica
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This paper addresses the functional reliability and the complexity of reconfigurable antennas using graph models. The correlation between complexity and reliability for any given reconfigurable antenna is defined. Two methods are proposed to reduce failures and improve the reliability of reconfigurable antennas. The failures are caused by the reconfiguration technique or by the surrounding environment. These failure reduction methods proposed are tested and examples are given which verify these methods.

Aplicações de antenas inteligentes e equalização concorrente em sistemas WCDMA/HSDPA; Applications of smart antennas and concurrent equalization on WCDMA/HSDPA systems

Fabbryccio Akkazzha Chaves Machado Cardoso
Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 17/12/2004 Português
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Nesta tese são investigados e propostos diferentes algoritmos adaptativos para antenas inteligentes e equalização em receptores de usuário no enlace de descida de sistemas WCDMA/HSDPA. Considerando o tema de equalização de canal, propõe-se um algoritmo adaptativo de retro-propagação com subsistemas concorrentes. Esta técnica de equalização explora características específicas de um sinal WCDMA e foi inspirada na técnica de equalização cega concorrente desenvolvida por Fernando C. C. de Castro et al. Com relação a antenas inteligentes, propõe-se um esquema adaptativo de recepção espaço-temporal de múltiplos alvos, denominado MT-STR, que emprega K processadores de antenas e um com binador de sinais dos vários alvos, ou fingers, do receptor. Esta técnica de recepção foi testada num cenário de soft-handover bastante severo, envolvendo muitos sinais interferentes. Ainda no escopo de antenas inteligentes, estudou-se também o efeito do acoplamento mútuo e do descasamento de amplitude e fase em arranjos co-lineares de antenas dipolo de meia onda; This dissertation investigates and proposes different algorithms for smart antennas and channel equalization aiming at WCDMA HSDPA downlink receivers. Considering the channel equalization issue...

Um novo tipo de antena para radar aerotransportado : Yagi tridimensional; A novel antena for airborne radar : tridimensional Yagi

Juliano Rodrigues Brianeze
Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 28/08/2008 Português
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Sistemas embarcados usando Radar de Abertura Sintética (Synthetic Aperture Radar - SAR), em plataformas aerotransportadas ou orbitais, têm sido cada vez mais usados para sensoriamento remoto. Quando estes sistemas são aplicados para estudos de cobertura vegetal e biomassa, sinais com freqüências acima de 1 GHz penetram pouco na vegetação. Já o uso de freqüências na banda P (400 MHz) permite uma maior penetração, possibilitando a detecção da superfície do terreno subjacente. A escolha da antena para esses sistemas é um ponto muito importante, já que vários de seus parâmetros estão diretamente ligados ao desempenho do sistema. O objetivo deste trabalho é propor um novo tipo de antena Yagi que seja eficiente para sistemas SAR aerotransportados: uma combinação das antenas Quasi-Yagi e Yagi-Uda. Da primeira é mantido o balun de microfita, que garante uma grande largura de banda. Já os elementos radiantes (driver e diretores), permanecem semelhantes aos de uma antena Yagi-Uda, ou seja, dipolos cilíndricos de metal. A antena foi projetada para ser fixada ao corpo de uma aeronave, usando a fuselagem para moldar seu padrão de radiação. Após a proposta de um modelo final para a nova antena Yagi, chamado Yagi Tridimensional...

Etiqueta de RFID em UHF para objetos metálicos; UHF RFID Tag for metallic objects

Manoel Vitorio Barbin
Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 30/01/2015 Português
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A identificação de objetos através de ondas de radiofrequência ou RFID (Radio Frequency Identification) é uma tecnologia onde uma etiqueta, colocada em um objeto, tem suas informações lidas por um sistema de processamento remoto. Embora esta não seja uma tecnologia recente, sua utilização tem apresentado constante crescimento nos últimos anos. Atualmente, RFID é apontada com uma das principais tecnologias habilitadoras da internet do futuro, a Internet das Coisas, IoT (Internet of Things). Operando principalmente em faixas destinadas para o uso de aplicações médicas, científicas e industriais, ISM (Industrial, Scientific and Medical), sistemas de RFID apresentam diferentes características em função da banda de frequências utilizada. Em UHF (Ultra High Frequency), os sistemas de RFID que fazem uso de etiquetas passivas, são considerados como uma solução com bom desempenho para a identificação de objetos em distâncias que variam de alguns poucos centímetros a vários metros. Contudo, a distância de identificação depende do material que constitui um dado objeto. Por exemplo, metais estão entre os materiais que degradam significativamente o desempenho de sistemas de RFID em UHF, reduzindo a distância de identificação. Diversas soluções de etiquetas têm sido desenvolvidas com o objetivo de torná-las...

Physical limitations on antennas

Fonte: Research Laboratory of Electronics, Massachusetts Institute of Technology Publicador: Research Laboratory of Electronics, Massachusetts Institute of Technology
Formato: 85 p.; 5053351 bytes; application/pdf
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John Ruze.; "May 27, 1953."; Bibliography: p. 84-85.; Army Signal Corps Contract DA36-039 sc-42607 Project 132B Dept. of the Army Project 3-99-10-022

Physical limitations of omnidirectional antennas

Fonte: Massachusetts Institute of Technology, Research Laboratory of Electronics Publicador: Massachusetts Institute of Technology, Research Laboratory of Electronics
Formato: 21 p.; 1363159 bytes; application/pdf
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L.J. Chu.; "May 1, 1948."; Includes bibliographical references.; Army Signal Corps Contract No. W-36-039 sc-32037.

Relação de troca entre eficiência energética e eficiência espectral em redes de comunicação sem fio com múltiplas antenas

Rayel, Ohara Kerusauskas
Fonte: Curitiba Publicador: Curitiba
Tipo: Tese de Doutorado
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In this dissertation, we investigate the Energy Efficiency-Spectral Efficiency (EE-SE) trade- off of a multiple antenna wireless communication system employing Transmit Antenna Selection/Maximum Ratio Combining (TAS) scheme. A realistic power consumption model (PCM) is considered, and it is shown that the use of TAS/MRC can provide significant energy savings when compared to Multiple-Input Multiple-Output (MIMO) in the low to medium spectral efficiency region, regardless the number of antennas, as well as outperform transmit beamforming scheme (MRT) for the entire spectral efficiency range. For a fixed number of receive antennas, our results also show that the energy efficiency gain of TAS over MIMO becomes even greater as the number of transmit antennas increases. The optimal value of spectral efficiency that maximizes the energy efficiency is obtained analytically, and confirmed by numerical results. Expressions that evaluate the capacity and the EE-SE trade-off for TAS under the influence of receiver correlation are obtained and it is shown that considering a non- realistic power consumption model can lead to mistakes when comparing TAS and MIMO.; CAPES; Nesta tese, a relação de troca entre Eficiência Espectral e Eficiência Energética (EE-SE...

Optimizing the radiation pattern of smart antennas using genetic algorithms

Hsu, Chao-Hsing
Fonte: FIU Digital Commons Publicador: FIU Digital Commons
Tipo: Artigo de Revista Científica
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This work is directed towards optimizing the radiation pattern of smart antennas using genetic algorithms. The structure of the smart antennas based on Space Division Multiple Access (SDMA) is proposed. It is composed of adaptive antennas, each of which has adjustable weight elements for amplitudes and phases of signals. The corresponding radiation pattern formula available for the utilization of numerical optimization techniques is deduced. Genetic algorithms are applied to search the best phase-amplitude weights or phase-only weights with which the optimal radiation pattern can be achieved. ^ One highlight of this work is the proposed optimal radiation pattern concept and its implementation by genetic algorithms. The results show that genetic algorithms are effective for the true Signal-Interference-Ratio (SIR) design of smart antennas. This means that not only nulls can be put in the directions of the interfering signals but also simultaneously main lobes can be formed in the directions of the desired signals. The optimal radiation pattern of a smart antenna possessing SDMA ability has been achieved. ^ The second highlight is on the weight search by genetic algorithms for the optimal radiation pattern design of antennas having more than one interfering signal. The regular criterion for determining which chromosome should be kept for the next step iteration is modified so as to improve the performance of the genetic algorithm iteration. The results show that the modified criterion can speed up and guarantee the iteration to be convergent. ^ In addition...

Enhancement of wireless networks with heterogeneous antennas

Wang, Yong
Fonte: FIU Digital Commons Publicador: FIU Digital Commons
Tipo: Artigo de Revista Científica
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In recent years, wireless communication infrastructures have been widely deployed for both personal and business applications. IEEE 802.11 series Wireless Local Area Network (WLAN) standards attract lots of attention due to their low cost and high data rate. Wireless ad hoc networks which use IEEE 802.11 standards are one of hot spots of recent network research. Designing appropriate Media Access Control (MAC) layer protocols is one of the key issues for wireless ad hoc networks. ^ Existing wireless applications typically use omni-directional antennas. When using an omni-directional antenna, the gain of the antenna in all directions is the same. Due to the nature of the Distributed Coordination Function (DCF) mechanism of IEEE 802.11 standards, only one of the one-hop neighbors can send data at one time. Nodes other than the sender and the receiver must be either in idle or listening state, otherwise collisions could occur. The downside of the omni-directionality of antennas is that the spatial reuse ratio is low and the capacity of the network is considerably limited. ^ It is therefore obvious that the directional antenna has been introduced to improve spatial reutilization. As we know, a directional antenna has the following benefits. It can improve transport capacity by decreasing interference of a directional main lobe. It can increase coverage range due to a higher SINR (Signal Interference to Noise Ratio)...

60 ghz aperture-coupled dielectric resonator antennas fed by a half-mode substrate integrated waveguide

Lai, Q.; Fumeaux, C.; Hong, W.; Vahldieck, R.
Fonte: IEEE-Inst Electrical Electronics Engineers Inc Publicador: IEEE-Inst Electrical Electronics Engineers Inc
Tipo: Artigo de Revista Científica
Publicado em //2010 Português
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Dielectric resonator antennas (DRAs) fed by a halfmode substrate integrated waveguide (HMSIW) are proposed and studied in this paper. The investigated antenna configuration consists of a dielectric resonator (DR) mounted on the conducting back plane of an HMSIW. Energy is coupled from the interior HMSIW to the DR through an aperture between them. Using this excitation scheme, a 60 GHz linearly polarized HMSIW-fed DRA is first designed by applying a transverse rectangular slot to feed a dielectric cylinder. This design experimentally exhibits a bandwidth of 24.2% for S11 < -10 dB. In particular, a gain higher than 5.5 dB and a radiation efficiency between 80% and 92% are obtained over the whole operation band, indicating that the HMSIW can be an efficient feed for DRAs operating around 60 GHz. In addition to this linearly polarized example, a DRA of circular polarization, coupled through a pair of cross slots, is also designed, presenting a measured 3-dB axial ratio bandwidth of 4.0%.; Qinghua Lai, Christophe Fumeaux, Wei Hong and Rüdiger Vahldieck

MATNEC: an in-house developed tool for electromagnetic simulation and evolutionary optimization of wire antennas

Zhao, S.; Fumeaux, C.; Fickenscher, T.
Fonte: Institute of Electrical and Electronics Engineers (IEEE) Publicador: Institute of Electrical and Electronics Engineers (IEEE)
Tipo: Conference paper
Publicado em //2014 Português
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Various techniques of numerical electromagnetic computation have been widely used for decades in the design of antennas. In particular, the Numerical Electromagnetic Code was developed based on the method of moments to solve integral equations for current distributions, and thus, it is particularly efficient for the modeling and analysis of wire antennas and other metal structures. The computation load can, however, increase significantly with the increase of complexity in structure modeling. Radial basis functions are employed for geometry description to ease such burden by representing structural variations with a minimal number of variables. Evolutionary optimizations are used to explore a wider solution space in a timely manner in the pursuit of near-optimal solution in a multivariable environment. An in-house tool called MATNEC integrating modeling, simulation, analysis, and optimization is developed, which can successfully deliver near-optimal solutions under a pre-defined fitness function, considering both antenna efficiency and bandwidth. Helical antennas with variations in radius and pitch are successfully optimized, which effectively verifies the robustness of MATNEC and methodology applied; S. Zhao, C. Fumeaux, and T. Fickenscher

Radio-over-Fiber Aided Base Station Coordination for OFDM

García Armada, Ana; Thomas, Varghese Antony; El-Hajjar, M.; Hanzo, Lajos
Fonte: IEEE - The Institute Of Electrical And Electronics Engineers, Inc Publicador: IEEE - The Institute Of Electrical And Electronics Engineers, Inc
Tipo: info:eu-repo/semantics/acceptedVersion; info:eu-repo/semantics/bookPart; info:eu-repo/semantics/conferenceObject
Publicado em 15/09/2014 Português
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Radio over Fiber (RoF) distribution aided co-operation of Remote Access Points (RAPs) is proposed for jointly transmitting data to the users in the downlink (DL) of a Multiple Input Multiple Output Orthogonal Frequency Division Multiplexing (MIMO-OFDM) system. Joint transmission is performed with the aid of Block Diagonalization (BD), where the transmitted signal is pre-distorted in order to overcome the non-linearity imposed by the optical modulator. We demonstrate that with adequate design, the users can obtain high data rates with very small degradation introduced by the RoF transmission. Quantitatively, when M=7 RAPs, each equipped with t=2 transmit antennas (TAs) each, cooperate to serve N=7 simultaneous users, also equipped with r=2 receive antennas (RAs), the SNR degradation is kept below 0.1 dB compared to a system assuming a perfect RoF channel. On the other hand, the SNR performance degradation is around 1.2 dB, when the number of antennas at the transmitters and the receivers is increased to t=r=8.; This work was supported by projects CSD2008-00010, TEC2011-29006- C03-03 and by a mobility grant of Spanish Ministry of Education. The financial support of the UK Government’s Engineering & Physical Sciences Research Council (EPSRC) as well as that of the Research Councils UK (RCUK) and of the European Research Council’s Senior Research Fellow Grant is also gratefully acknowledged.; This proceding at: IEEE 80th Vehicular Technology Conference (VTC)Fall. Took place 2014...

Design and development of microwave patch antennas using conductive polymers.

Verma, Akhilesh
Fonte: Universidade de Adelaide Publicador: Universidade de Adelaide
Tipo: Tese de Doutorado
Publicado em //2012 Português
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Recent advances in the electrical conductivity levels of Conducting Polymers (CP) and impressive improvements in their stability are making these materials very attractive potential alternatives to copper in planar antennas. This is particularly so in applications where light weight, inexpensive and/or wearable/conformal antennas are a consideration. There have been isolated efforts in the past towards using CP as material for antenna and transmission line design. This thesis endeavours to provide a systematic study of key factors that are important for the understanding of these materials, their design and simulation as basis material for building microwave antennas. The thesis could be considered as made up of two parts. The first part (Chapter 2 and Appendix A) presents a mathematical model of electrical conduction and permittivity in CPs as a function of dopant concentration and frequency. The electrical conduction and permittivity are very dispersive for these materials primarily due to different relaxation times exhibited by the conduction electrons. This part also develops closed-form expressions formulas for rapid estimation of the effective permittivity of microstrip lines on multi-layer substrates. A 2D finite element eigen-mode analysis leading to the effective permittivity for two and three layer microstrip line structures is used as a reference solution and successfully validates the closed-form expressions. The second part (Chapter 3 and 4) presents the design...

Design and analysis of a folded meander dipole antenna using the MININEC program

Barros, Pedro A.
Fonte: FIU Digital Commons Publicador: FIU Digital Commons
Tipo: Artigo de Revista Científica Formato: application/pdf
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The Mini-Numerical Electromagnetic Code (MININEC) program, a PC-Compatible version of the powerful NEC program, is used to design a new type of reduced-size antenna. The validity of the program to model simple well-known antennas, such as dipoles and monopoles, is first shown. More complex geometries such as folded dipoles, and meander dipole antennas are also analysed using the program. The final design geometry of a meander folded dipole is characterized with MININEC, yielding results that serve as the basis for the practical construction of the antenna. Finally, the laboratory work with a prototype antenna is described, and practical results are presented.

Mixed signal processor for a robust symmetrical number system direction finding antenna

Babb, Charles F.
Fonte: Monterey California. Naval Postgraduate School Publicador: Monterey California. Naval Postgraduate School
Formato: xvi, 100 p. : ill. (some col.) ; 28 cm.
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Approved for public release; distribution is unlimited.; Approved for public release; distribution is unlimited.; This applied research project has designed, simulated, constructed and tested the performance of a processing system for a prototype direction finding antenna. A mixed signal architecture to derive the direction of arrival from a Robust Symmetrical Number System (RSNS) encoded direction finding array is based on a new phase sampling interferometer approach that can be easily incorporated into established techniques to provide a high resolution, small-baseline array with few number of phase sampling comparators. The approach is based on preprocessing the received signal using the RSNS. The preprocessing is used to decompose the spatial filtering operation into a number of parallel suboperations (moduli) that are of smaller computational complexity. A much higher direction finding spatial resolution is achieved after the N different moduli are used and the results of the low precision suboperations are recombined, in addition to the reduction of the number of possible encoding errors due to the RSNS' inherent Gray-coding properties. This has resulted in a four inch antenna array being able to attain an angular resolution of less than 1.8 degrees with a continuous field of view of 120 degrees. The accompanying electronics occupy two 6 inch by 8 inch printed circuit boards...

Genetic algorithm optimization applied to planar and wire antennas

Wyant, Andrea
Fonte: Rochester Instituto de Tecnologia Publicador: Rochester Instituto de Tecnologia
Tipo: Tese de Doutorado
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Antenna design has grown more stringent and difficult over the years as the world becomes strictly a wireless environment. The inherent tradeoffs that exist between gain, radiation pattern, bandwidth, and physical size and the multiple parameters that must be considered make antenna design a lengthy and tedious process. Methods have been devised which automate this complex process of antenna optimization through the use of genetic algorithms, particle swarm optimization, and simulated annealing. Genetic algorithms are capable of handling a large number of design parameters and work for optimization problems that have discontinuous or non-differentiable multi-dimensional solution spaces, making them ideal for antenna optimization. In the present work, a genetic algorithm has been used for size reduction in microstrip patch antennas and design tradeoff optimization between beamwidth and gain in helical antennas. A method for reducing the size of microstrip patch antennas by up to 75% by removing rectangular and circular slots from the metal of the microstrip patch is presented. A solid patch antenna that resonates at 10 GHz is forced to resonant at 6 GHz through the removal of the different shaped slots. Given the number and shape of the slots...

Antenna Saturation Effects on MIMO Capacity

Pollock, Tony; Abhayapala, Thushara; Kennedy, Rodney
Fonte: Institute of Electrical and Electronics Engineers (IEEE Inc) Publicador: Institute of Electrical and Electronics Engineers (IEEE Inc)
Tipo: Conference paper
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A theoretically derived antenna saturation point is shown to exist for MIMO systems, at which the system suffers a capacity growth decrease from linear to logarithmic with increasing antenna numbers. We show this saturation point increases linearly with the radius of the region containing the receiver antennas and is independent of the number of antennas. Using an alternative formulation of capacity for MIMO systems we derive a closed form capacity expression which uses the physics of signal propagation combined with statistics of the scattering environment. This expression gives the capacity of a MIMO system in terms of antenna placement and scattering environment and shows that the saturation effect is due to spatial correlation between receiver antennas.

Noncollimating MmW polyethylene lens mitigating dual-source offset from a Tx/Rx WiGig module

Bisognin, A.; Titz, D.; Ferrero, F.; Jacquemod, G.; Pilard, R.; Gianesello, F.; Gloria, D.; Lugara, D.; Lima, E. B.; Costa, J. R.; Fernandes, C. A.; Luxe, C.
Fonte: IEEE - Institute of electrical electronics and engineers Publicador: IEEE - Institute of electrical electronics and engineers
Tipo: Artigo de Revista Científica
Publicado em //2015 Português
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The design of a micromachined polyethylene lens for WiGig modules is described and its electromagnetic characteristics are measured. The lens is electromagnetically fed by linearly polarized Tx and Rx patch antennas integrated in an existing ball-grid-array (BGA) organic module. Antennas are separated from each other by a distance of 4.45 mm (0.89lambda at 60 GHz). The goal of the lens is to increase the gain of each antenna while lowering the beam depointing effect due to their offset position regarding the focal point of the lens. A geometrical optics/physical optics (GO/PO) hybrid method is applied to the design and analysis of the lens shape for noncollimating purpose. Using a lens height of 30 mm for both Tx and Rx antennas, a 13-dBi minimum realized gain from 54 to 66 GHz is obtained. Compared to an elliptical lens providing an equivalent realized gain over the same bandwidth, the depointing angle from the boresight direction is reduced from 15° to 4°. Full-wave simulations are verified by measurements.