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1
Touhami, Abdellah. "Optimisation multi-objectif d'antennes superdirectives compactes à balayage de faisceau pour des passerelles domestiques 5G sans fil." Electronic Thesis or Diss., Université de Rennes (2023-....), 2024. http://www.theses.fr/2024URENS002.
Анотація:
L’évolution des standards de communication impose le besoin des architectures antennaires plus sophistiqués associés à des techniques de diversité d’antennes et de formation de faisceaux. Ce type d’antennes offre des nouvelles possibilités pour les applications sans fil en termes d’efficacité spectrale, de fiabilité des liens radio, de réduction de l’impact environnementale ainsi que l’accroissement des capacités des systèmes de communications. Cependant, les techniques conventionnelles de formation de faisceaux entraînent souvent une augmentation significative de la taille de l’antenne. Par conséquent, l’intégration de tel système dans des petits appareils sans fil est relativement limitée. Les réseaux d’antennes compactes et superdirectifs constituent une solution innovante et attrayante pour surmonter ces problèmes. Néanmoins, ils présentent nombreux inconvénients notamment une faible efficacité de rayonnement, un très faible gain et une bande passante très étroite. Ces inconvénients limitent l'utilité des réseaux superdirectifs pour répondre aux besoins des technologies sans fil de nouvelles générations. Dans cette thèse, nous proposons de nouvelles méthodes d’optimisation multi-objectif, basées sur la théorie des modes caractéristiques (NCM), la théorie du facteur de réseau ainsi que les réseaux de neurones artificiels (RNA) pour la conception et le développement de nouvelles architectures antennaires compactes, superdirectives, efficaces et large bande pour des applications 5GThe evolution of wireless communication impose the need for more sophisticated antenna architectures, combined with antenna diversity and beamforming techniques. This type of antenna offers new possibilities for wireless applications in terms of spectral efficiency, radio link reliability, reduced environmental impact and increased communications system capacity. However, conventional beamforming techniques often lead to a significant increase in antenna size. As a result, the integration of such systems into small wireless devices is relatively limited. Compact, superdirective antenna arrays offer an innovative and attractive solution for both beamforming needs and integration in small volumes. However, they exhibits multiple drawbacks, including low radiation efficiency, low gain and narrow bandwidth. These drawbacks limit the usefulness of superdirective arrays to meet the needs of new-generation wireless technologies. In this thesis, we propose new multi-objectives optimization methods, based on network characteristic mode theory (NCM), array factor theory as well as artificial neural networks (ANN), for the design and the development of new compact, superdirective, efficient and wideband antenna architectures for 5G applications
2
Yong, Su-Khiong. "Compact antenna arrays for mobile communications." Thesis, University of Edinburgh, 2003. http://hdl.handle.net/1842/11648.
Анотація:
The contributions of this thesis are four fold. Firstly, the implementation of COST 259 directional channel model in terms of tapped delay line is developed. While the implemented channel model facilities link level simulation, capacity analysis indicates that the delay spread has relatively small impact as compared to the azimuth spread (AS) on the channel capacity. Secondly, an antenna model which incorporates various antenna effects into the performance study of antenna arrays (AAs0 is developed. A comprehensive study of these effects through computer simulations reveals that the use of ideal parameters in the literature always over-predicts the actual system performance. The use of different antenna configurations yields different results with some arrays performing better in certain scenario than others. Furthermore, a proposed mutual coupling (MC) model explains the conflicting results reported to date in the literature. The overall effect of MC is to reduce the system performance despite lower fading correlation is being obtained between the pair of elements when MC is taken into account. Thirdly, the impact of using different azimuth-of-arrival (AOA) and elevation-of-arrival (EOA) distributions on the performance of various AAs is found to be minimal. The determining factor for the AA performance is the standard deviation of the underlying distribution. Finally, three-dimensional spatial fading correlation (SFC) models for several CAA geometries are developed. The closed-form SFC functions are expressed in terms of AOA, EOA and the geometry of the AA under study. Such closed-form expressions can be used to determine the correlation matrices at both base station and mobile station and thus are important in assisting the capacity analysis of single-input multiple-output and multiple-input and multiple-output systems. Furthermore, the developed SFC functions also enable the sensitivity of the AAs to be evaluated through the performance patterns. The results provide invaluable insight that can ultimately assist the design of AA algorithms. An extensive analysis on the array’s sensitivity shows that the system performance is more AS dependent than ES while the effect of mean-azimuth-of-arrival and mean-evaluation-of-arrival is array dependent. The results also show that the AS is the primary factor affecting antenna correlation and the impact of ES is mainly noticeable at small AS values. Nevertheless, in evaluating the performance of AAs, both AOQ and EOA must be taken in account. Capacity analysis also demonstrates the practicability of deploying electromagnetic vector sensor (EVS) and EVS arrays as compact AA receivers.
3
Abdelaziz, Abdelaziz Abdelmonem. "Compact multi-band microstrip planar antennas and arrays." Thesis, Cranfield University, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.315345.
4
Eck, James Arthur. "Compact Antennas and Arrays for Unmanned Air Systems." BYU ScholarsArchive, 2014. https://scholarsarchive.byu.edu/etd/4297.
Анотація:
A simple and novel dual-CP printed antenna is modelled and measured. The patch antennais small and achieves a low axial ratio without quadrature feeding. The measured pattern showsaxial ratio pattern squinting over frequency. Possible methods of improving the individual element are discussed, as well as an array technique for improving the axial ratio bandwidth. Three endfire printed antenna structures are designed, analyzed, and compared. The comparison includes an analysis of costs of production for the antenna structures in addition to their performance parameters. This analysis concludes that cost of materials primarily reduces the size of antennas for a given gain and bandwidth. An antenna stucture with an annular beam pattern for down-looking navigational radar is proposed. The antenna uses sub-wavelength grating techniques from optics to achieve a highly directive planar reflector which is used as a ground plane for a monopole. A fan-beam array element is fabricated for use in a digitally steered receive array for obstacle avoidance radar. The steered beam pattern is observed. The element-dependent phase shifts for a homodyned signal in particular are explored as to their impact on beam steering.
5
Calvelo, Santos Daniel Emilio. "Observations of X-ray binaries using the Australia Telescope Compact Array-Compact Array Broadband Backend." Thesis, University of Southampton, 2012. https://eprints.soton.ac.uk/343755/.
Анотація:
The exploration of radio emission from the relativistic jets of X-ray binaries has become key to understanding accretion onto compact objects. Upgrades to existing radio telescope arrays have improved the ability of these instruments to detect faint sources and their unique behaviours. In this thesis I address the use of one such instrument in observing several X-ray binary systems: the Australia Telescope Compact Array - Compact Array Broadband Backend (ATCA-CABB). Firstly, a study of the adverse effects that may arise when imaging spectrally variable sources using broad bandwidths, with emphasis on ATCA-CABB. Images are produced from model data and examined to find any false structures. I then discuss complications that such features may cause when attempting to interpret real structure in images. Secondly, the results of attempts to observe the black hole X-ray binaries, GRO J1655-40 and XTE J1550-564, in quiescence with ATCA-CABB are presented. Upper limits from the non-detection of these sources are used in exploring the lower luminosity region of the radio/X-ray correlation for hard state black hole X-ray binaries and the implications of “universal” scatter is discussed. Thirdly, a 16 day campaign observing the radio emission of the neutron star Xray binary Circinus X-1 over a complete orbit during an historically faint state is presented. Variability in the source is examined and corrected images are compared with archival maps in order to find any differences. I discuss my findings in terms of secular changes in jet geometry and behaviour. Finally, the first successful millimetre detections of neutron star X-ray binaries Circinus X-1 and Scorpius X-1 are presented. Sub-arcsecond jet structure in Circinus X-1 is compared to the existing centimetre maps, providing additional support for theories proposed earlier in the thesis. The radio to mm spectrum of both sources is estimated and discussed. This thesis concludes with a description of the broader impacts of the above projects, as well as possibilities for future research in each field.
6
Dahlberg, Timoteus. "Compact Representation and Efficient Manipulation of Sparse Multidimensional Arrays." Thesis, Umeå universitet, Institutionen för datavetenskap, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-92841.
Анотація:
Efficient manipulation of sparse multidimensional arrays, or tensors, is of interest because their decompositions have applications in many different areas. These areas include neuroscience, machine learning, psychometrics, data mining, numerical analysis, and more. This thesis aims to develop the performance-critical parts of a library for manipulating sparse multidimensional arrays by focusing on sorting them in one or more dimensions—a fundamental operation on which many other operations can be built. High performance is achieved by tailoring algorithms to a compact representation scheme. Evaluation is done on different algorithms and implementation techniques. The result is shown to be 20 to 70 times faster than qsort in the C standard library. The resulting library is open source.
7
Bougan, Timothy B. "COMPACT HIGH-SPEED DISK RECORDER." International Foundation for Telemetering, 1994. http://hdl.handle.net/10150/608597.
Анотація:
International Telemetering Conference Proceedings / October 17-20, 1994 / Town & Country Hotel and Conference Center, San Diego, CaliforniaIn order to meet the high-speed and high-density recording requirements for today's development and testing environments, we are seeking to merge the cutting edge technologies of tiny, high-performance disk drives and field programmable gate arrays (FPGAs) to build a high-speed compact disk recorder (CHSDR). Specifically, we designed, built, and tested a multi-drive controller that handles the interleaving of data to eight inexpensive IDE drives. These drives and controller comprise a "cell" capable of transferring data at 2.45 MB/sec (4 to 5 times the rate of a single drive). Furthermore, these "cells" can be run in parallel (with a single controller interleaving data between the cells). This "tree" effect multiplies the data rate by the number of cells employed. For example, 8 cells (of 8 drives each) can reach nearly 20 MB/second (sustained) and can be built for less than $30,000. The drives we used are the size of match boxes (the Hewlett Packard KittyHawk). These tiny drives hold 42 megabytes each and can withstand 150 Gs while operating. The cell controller is a Xilinx 4005 FPGA. Furthermore, we've designed a 120 MB/sec RAM FIFO to buffer data entering the system (to account for unavoidable drive seek latencies). In short, the compact high-speed disk array is a small, relatively low cost recording solution for anyone requiring high data speed but modest data volume. Missile shots, nuclear tests, and other short-term experiments are good examples of such requirements.
8
Lovell, Jack James. "Development of smart, compact fusion diagnostics using field-programmable gate arrays." Thesis, Durham University, 2017. http://etheses.dur.ac.uk/12401/.
Анотація:
Fusion research requires high quality diagnostics to understand the complex physical processes involved. Traditional analogue systems are complex, large and expensive, and expansion of diagnostic capabilities is often impossible without building a completely new system at considerable expense. Field-programmable gate array (FPGA) technology can provide a solution to this problem. By implementing complex functionality and digital signal processing on an FPGA chip, diagnostic hardware can be greatly simplified and compacted. In this thesis we describe the enhancements of two diagnostics for the MAST-Upgrade tokamak using FPGA technology. Firstly, the design of the back end electronics for the new divertor bolometer is described. Results of tests of the new electronics at a number of sites, including lab-based testing and tokamak installations, are also presented. We demonstrate the correct functionality of the electronics and illustrate a number of important effects which must be taken into account when interpreting bolometer data on MAST-U. Secondly, we describe the new control and acquisition electronics developed for the MAST-U divertor Langmuir probe diagnostic. Much of the analogue control circuitry of the previous system has been upgraded to a digital implementation on an FPGA, which results in a significantly more compact and cost effective design. Given that MAST-Upgrade will feature around 850 Langmuir probes, these improvements are extremely important to keep the diagnostic manageable. Again, results are presented from the testing of the system at several sites, which both demonstrate the correct functionality of the new system and provide information on the diagnostic behaviour which needs to be accounted for when interpreting the probe data during MAST-U experiments.
9
Volmer, Christian. "Compact antenna arrays in mobile communications a quantitative analysis of radiator coupling." Ilmenau Univ.-Verl, 2009. http://d-nb.info/1000814149/04.
10
Volmer, Christian. "Compact antenna arrays in mobile communications A quantitative analysis of radiator coupling." Ilmenau Universitätsbibliothek Ilmenau, 2010. http://d-nb.info/1001147197/34.
11
Ip, Kenneth Ho Yan. "A compact four-element injection-locked scanning antenna array." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp05/MQ63018.pdf.
12
Rai, Binay. "X-ray view of compact objects." Thesis, University of North Bengal, 2021. http://ir.nbu.ac.in/handle/123456789/4755.
13
Tu, Wen-Hua. "Wideband phased array antennas and compact, harmonic-suppressed microstrip filters." [College Station, Tex. : Texas A&M University, 2006. http://hdl.handle.net/1969.1/ETD-TAMU-1110.
14
Kim, Sunghwan. "Phase shifter approaches for compact low-power phased array transmitters." Diss., [La Jolla] : University of California, San Diego, 2010. http://wwwlib.umi.com/cr/ucsd/fullcit?p3398530.
Анотація:
Thesis (Ph. D.)--University of California, San Diego, 2010.Title from first page of PDF file (viewed May 5, 2010). Available via ProQuest Digital Dissertations. Vita. Includes bibliographical references (p. 103-109).
15
Zhu, Fuguo. "Compact antennas and array for ultra-wideband communications and radars." Thesis, University of Kent, 2013. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.654097.
Анотація:
The allocation of the frequency spectrum from 3.1 to 10.6 GHz by the Federal Communications Commission (FCC) has attract~d much interest in various Ultra- . I wideband (UWB) applications including short-range, high-data-rate communication and high-resolution imaging radar/sensor due to its large bandwidth. This has increased the demands on the UWB systems and subsequently to stimulate the research activities in various UWB antenna designs. Challenges of the UWB antenna design include the wide impedance bandwidth, radiation stability, low profile, compact size, and low cost for portable consumer electronics applications. Moreover, dual-polarized UWB antennas are more attractive compared to single-polarized , antennas, as the channel capacity is significantly enhanced due to the polarization diversity technique. The performance of imaginglradar systems can also be improved by employing dual-polarized UWB antennas, since more information about the target can be obtained using a fully polarimetric system. To mitigate interferences with coexisting wireless systems operating over 3.3-3.6 GHz, 5.15-5.35 GHz, or 5.725-5.825 GHz bands, this work presents the design, development and measurement of printed band-notched antennas for UWB short-range indoor con1munications. These include UWB antennas with a single wide notched band, a single narrow notche? band, dual notched bands, and triple notched bands. Good band-notched performance is ach.ieved by using a high permittivity and low dielectric loss subsh'ate, and . inserting quarter-wavelength band-notched elements within the feed line. These antennas can achieve high gain suppression over 10 dB in each notched frequency band. In addition, they occupy a compact size of 28 mm by 28.5 mm due to the use.r0f a high permittivity substrate. For the purpose of alleviating the requirement on space for band-notched elements, a printed asymmetrical UWB antenna with .multiple notched bands is also designed, fabricated and measured. Only one single band-notChed element is required to notch each frequency due to its symmetry. This work also presents the design of two types of dual-polarized UWB patch antennas. One is a cavity-backed capacitively c01:lp~ed patch antenna which consists of a square patch and four capacitively coupled feeds to enhance the impedance bandwidth. Each feed 1 ----- - ----- is formed by a vertical isosceles trapezoidal patch and a horizontal isosceles triangular patch. The four feeds are connected to the microstrip lines that are printed on thy bottom layer of the grounded FR4 substrate. Two tapered baluns are util,ized to excite the antelma to achieve high isolation between the POlts and reduce the cross-polarization levels. In order to increase the antenna gain and reduce the backward radiation, a compaCt surface mounted cavity is integrated with the antenna. The antenna prototype has achieved an impedance bandwidth of 112% at (lS111 :::; -10 dB) whereas the coupling between the two ports is below -28 dB across the operating frequency range. The measured _ ~ntenna gain varies from 3.91 to 10.2 dBi for Port 1 and from 3.38to 9.21 dBi for POlt 2, with a 3-dB gain bandwidth of 107%. The second design is a slot-loaded patch antenna which consists of a square ring patch and four inclined triangular-shaped patches. The vertices of the triangular patches are connected to the micro strip lines which are printed on the bottom layer of the grounded FR4 substrate. The antenna prototype can provide two orthgonal polarizations with an impedance bandwidth (IS111 :::; -10 dB) of 113% and isolation of over 28 dB across the whole operating frequency band. The measured antenna gain varies from 2.09 to 7.66 dBi for Port 1 and from 0.02 to 6.77 dBi fcir Port 2 with a 3-dB gain bandwidth of 96%. Finally, a cOlnpact connected eight-e~ement UWB antenna array integrated with a wideband eight-way power divider is designed, fabricated and tested.
16
Spencer, Jonathan Cullinan. "A Compact Phased Array Radar for UAS Sense and Avoid." BYU ScholarsArchive, 2015. https://scholarsarchive.byu.edu/etd/5837.
Анотація:
As small unmanned aerial systems (UAS) are introduced into the national airspace, measures must be introduced to ensure that they do not interfere with manned aviation and other UAS. Radar provides an attractive solution because of its inherent range accuracy and because it works in diverse weather and lighting conditions. Traditional radar systems, however, are large and high power and do not meet the size, weight and power (SWaP) constraints imposed by UAS, and fully integrated automotive solution do not provide the necessary range. This thesis proposes a compact radar system that meets both the SWaP and range requirements for UAS and can act as a standalone sensor for a sense and avoid system (SAA). The system meets the field of view requirements motivated by the UAS sensing problem (120deg x 30deg) and tracks targets in range and azimuthal angle using a four element phased array receiver. The phased array receiver implements real time correlation and beamforming using a field programmable gate array (FPGA) and can track multiple targets simultaneously. Excluding antennas, the radar transceiver and signal processing platform weighs approximately 120g and is approximately the size of a whiteboard eraser (2.25in x 4in x 1in), which meets the payload requirements of many small (<25kg) UAS. To our knowledge, this is the first real time phased array radar that meets the sensing and SWaP requirements for small UAS.Our testing was done with the radar system on the ground, aimed at airborne UAS targets. Using antennas with a gain of 12 dB, and 800 milliwatts of transmitted power, the system detects UAS targets with a radar cross section of less than 0.1 square meters up to 150 meters away. The ground based system demonstrates radar detectability of extremely small UAS targets, and is scalable to further ranges by increasing antenna gain or adding additional elements. Based on our success in detecting airborne UAS, we conclude that radar remains a feasible option for a UAS collision avoidance sensor.
17
DeJean, Gerald Reuben. "Design of compact antennas in multilayer technology for wireless communications : WLAN applications." Available online, Georgia Institute of Technology, 2005, 2004. http://etd.gatech.edu/theses/available/etd-12092004-162859/unrestricted/dejean%5Fgerald%5Fr%5F200505%5Fmast.pdf.
Анотація:
Thesis (M. S.)--Electrical and Computer Engineering, Georgia Institute of Technology, 2005.Joy Laskar, Committee Member ; Manos Tentzeris, Committee Member ; John Papapolymerou, Committee Chair. Includes bibliographical references.
18
Zhang, Shuai. "Investigating and Enhancing Performance of Multiple Antenna Systems in Compact MIMO/Diversity Terminals." Doctoral thesis, KTH, Elektroteknisk teori och konstruktion, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-116402.
Анотація:
Today, owners of small communicating device are interested in transmitting or receiving various multimedia data. By increasing the number of antennas at the transmitter and/or the receiver side of the wireless link, the diversity/Multiple-Input Multiple-Output (MIMO) techniques can increase wireless channel capacity without the need for additional power or spectrum in rich scattering environments. However, due to the limited space of small mobile devices, the correlation coefficients between MIMO antenna elements are very high and the total efficiencies of MIMO elements degrade severely. Furthermore, the human body causes high losses on electromagnetic wave. During the applications, the presence of users may result in the significant reduction of the antenna total efficiencies and highly affects the correlations of MIMO antenna systems. The aims of this thesis are to investigate and enhance the MIMO/diversity performance of multiple antenna systems in the free space and the presence of users. The background and theory of multiple antenna systems are introduced briefly first. Several figures of merits are provided and discussed to evaluate the multiple antenna systems. The decoupling techniques are investigated in the multiple antenna systems operating at the higher frequencies (above 1.7 GHz) and with high radiation efficiency. The single, dual and wide band isolation enhancements are realized through the half-wavelength decoupling slot, quarter-wavelength decoupling slot with T-shaped impedance transformer, tree-like parasitic element with multiple resonances, as well as the different polarizations and radiation patterns of multiple antennas. In the lower bands (lower than 960 MHz), due to the low radiation efficiency and strong chassis mode, the work mainly focused on how to directly reduce the correlations and enlarge the total efficiency. A new mode of mutual scattering mode is introduced. By increasing the Q factors, the radiation patterns of multiple antennas are separated automatically to reduce the correlations. With the inter-element distance larger than a certain distance, a higher Q factor also improved the total efficiency apart from the low correlation. A wideband LTE MIMO antenna with multiple resonances is proposed in mobile terminals. The high Q factors required for the low correlation and high efficiencies in mutual scattering mode is reduced with another mode of diagonal antenna-chassis mode. Hence, the bandwidth of wideband LTE MIMO antenna with multiple resonances mentioned above can be further enlarged while maintaining the good MIMO/diversity performance. The user effects are studied in different MIMO antenna types, chassis lengths, frequencies, port phases and operating modes. Utilizing these usefully information, an adaptive quad-element MAS has been proposed to reduce the user effects and the some geranial rules not limited to the designed MAS have also been given.QC 20130121
EU Erasmus Mundus External Cooperation Window TANDEM
19
Lepkowski, Stefan. "An ultra-compact and low loss passive beamforming network integrated on chip with off chip linear array." Thesis, Georgia Institute of Technology, 2015. http://hdl.handle.net/1853/53599.
Анотація:
The work here presents a review of beam forming architectures. As an example, the author presents an 8x8 Butler Matrix passive beam forming network including the schematic, design/modeling, operation, and simulated results. The limiting factor in traditional beam formers has been the large size dictated by transmission line based couplers. By replacing these couplers with transformer-based couplers, the matrix size is reduced substantially allowing for on chip compact integration. In the example presented, the core area, including the antenna crossover, measures 0.82mm×0.39mm (0.48% the size of a branch line coupler at the same frequency). The simulated beam forming achieves a peak PNR of 17.1 dB and 15dB from 57 to 63GHz. At the 60GHz center frequency the average insertion loss is simulated to be 3.26dB. The 8x8 Butler Matrix feeds into an 8-element antenna array to show the array patterns with single beam and adjacent beam isolation.
20
Debard, Alexandre. "Analyse et optimisation d'antennes réseaux compactes superdirectives." Thesis, Université Grenoble Alpes, 2020. http://www.theses.fr/2020GRALT058.
Анотація:
Cette thèse a pour objectif l’étude et la recherche d’amélioration de la technologie d’antenne réseau superdirective. Cette technologie a récemment été rééxaminée dans la littérature car elle peut apporter des fonctionnalités intéressantes pour les applications de télécommunication futures. L’examen de ce type d’antenne est donc conduit à travers l’outil de la décomposition en ondes sphériques qui permet l’étude générale des limites de directivité ou de gain, en considérant des pertes d’énergie dans l’antenne. La théorie classique des antennes réseau end-fire est aussi revue, dans le cas de réseaux à espace inter-éléments uniformes et à éléments indépendamments excités. Cette étude fournit une évaluation analytique de l’efficacité et de la sensibilité à la précision des coefficients d’excitation.Les dipôles infinitésimaux et les sources de Huygens sont considérés dans une proposition de développement qui lie la théorie des réseau et de la décomposition en ondes sphériques. Cette contribution fournit une preuve formelle de la limite de directivité des réseaux end-fire de sources de Huygens ainsi qu’une borne supérieure de la directivité des réseaux de dipôles, quand la distance inter-éléments tend vers zéro.. De plus, il est montré comment la théorie classique des antennes réseau peut aussi être utilisée pour extraire des coefficients d’excitations qui maximisent le gain plutôt que la directivité, quand des résistances de pertes sont considérées. Un examen est aussi fait selon la taille d’antenne pour montrer quelles conditions sont les plus favorables pour l’utilisation de réseaux end-fire optimisés pour le supergain ou pour la superdirectivité.Dans une seconde partie, les implémentations pratiques d’antennes superdirectives sont revue dans l’état de l’art, en se concentrant sur les sources de Huygens et les réseaux compacts end-fire. L’architecture d’implémentation choisie de réseau à éléments parasites est ensuite détaillée est étudiée dans le but de minimiser le recours à des résistances positives ou négatives. Cela mène à la conception et aux mesures de cinq prototypes qui visent à atteindre le maximum de gain ou de directivité possible, pour une taille d’antenne limitée, avec des réseaux end-fire de deux, trois et quatre dipôlesThe purpose of this thesis is to study and seek improvement of the superdirective antenna array technology. This technology has been recently re-examined in the literature since it can bring some interesting functionalities in the future telecommunication applications. The examination of this type of antenna is thus conducted through the use of Spherical Wave Expansion which allows for the general study of directivity limits as well as gain limits, considering lossy antennas. The classical theory of end-fire array antennas is also reviewed, in the case of uniformly spaced tapered arrays, providing theoretical evaluation of efficiency and sensitivity to source feeding precision.Infinitesimal dipoles and Huygens sources are considered in a proposed development that links array theory and Spherical Wave Expansion. This contribution provides a formal proof for the directivity limit of Huygens-source-based end-fire arrays as well as an upper bound for the directivity of dipole-based arrays, when the inter-element spacing tends to zero. Moreover, it is shown how classical array theory can also be used to derive excitation coefficients that maximize gain rather than directivity, when loss resistances are considered. An examination over antenna size is also made to demonstrate which conditions are most favorable for the use of such supergain or superdirective end-fire array optimization.In a second part, practical implementations of superdirective antennas are surveyed, focusing on Huygens sources and compact end-fire array designs. The chosen implementation architecture of parasitic element arrays is then detailed and studied, in order to minimize the requirement for negative or positive resistive loads. This lead to the design and measurement of five prototypes that aim at achieving the maximum possible gain or directivity for a limited radiator size, with two-, three- and four-dipole end-fire arrays
21
Zepeda, Paola. "Modeling and design of compact microwave components and systems for wireless communications and power transmission." Texas A&M University, 2004. http://hdl.handle.net/1969.1/322.
Анотація:
The contribution of the work here presented involves three main topics: Wireless Power Transmission (WPT) technology, phased array systems, and microwave components design and modeling. The first topic presents the conceptual design of a WPT system at 2.45GHz with 90% efficiency and 1MW of DC output power. Second, a comparative study between 2.45 and 35GHz WPT operation is provided. Finally, the optimization of a taper distribution with reduced thermal constraints on a sandwich transmitter is realized. For a 250- and 375-m antenna radius, 89.7% of collection efficiency with 29% reduction in maximum power density (compared to the Gaussian), and 93% collection efficiency with 39% reduction of maximum power density, are obtained respectively with two split tapers. The reduction in maximum power density and the use of split taper are important to alleviate the thermal problems in high power transmission.
For the phased array project, the conceptual design of a small-scale system and in-depth analysis using two main approaches (statistical and field analysis) is realized. Practical aspects are addressed to determine the phased array main design features. The statistical method provides less accurate results than the field analysis since it is intended for large arrays. Careful theoretical analysis led to good correlation between statistical, field analysis and experimental results.
In the components chapter, efficient loop transitions used in a patch antenna array are designed at K- and W-band. Measured insertion loss (IL) K-band loop is under 0.4dB. The K- and W-band antenna array measured broadside gains are 23.6dB at 24.125GHz and 25dB at 76.5GHz with return loss under 9.54dB from 24 to 24.4GHz and 12 dB from 75.1 to 77.3GHz, respectively. Also, a multilayer folded line filter is designed at 5.8GHz and compared to planar ring filters. Improved measured bandwidth from 2GHz to 7.5GHz and IL of 1.2dB are obtained with approximately half the size of a planar ring resonator. Thirdly, a simplified switch model is implemented for use in broadband phased-shifters. The model presents very good fit to the measured results with an overall total error under 3%, magnitude error less than 8%, and phase errors less than ±0.4°.
22
Steffens, Christian [Verfasser], Marius [Akademischer Betreuer] Pesavento, and Marc [Akademischer Betreuer] Pfetsch. "Compact Formulations for Sparse Reconstruction in Fully and Partly Calibrated Sensor Arrays / Christian Steffens ; Marius Pesavento, Marc Pfetsch." Darmstadt : Universitäts- und Landesbibliothek Darmstadt, 2018. http://d-nb.info/1153123495/34.
23
Anreddy, Vikram R. "Indoor MIMO Channels with Polarization Diversity: Measurements and Performance Analysis." Thesis, Available online, Georgia Institute of Technology, 2006, 2006. http://etd.gatech.edu/theses/available/etd-04112006-093641/.
Анотація:
Thesis (M. S.)--Electrical and Computer Engineering, Georgia Institute of Technology, 2006.Ingram Mary Ann, Committee Chair ; Durgin, Gregory David, Committee Member ; Williams, Douglas B, Committee Member.
24
Hoffman, Jeffrey Dean. "Using Blind Source Separation and a Compact Microphone Array to Improve the Error Rate of Speech Recognition." PDXScholar, 2016. https://pdxscholar.library.pdx.edu/open_access_etds/3367.
Анотація:
Automatic speech recognition has become a standard feature on many consumer electronics and automotive products, and the accuracy of the decoded speech has improved dramatically over time. Often, designers of these products achieve accuracy by employing microphone arrays and beamforming algorithms to reduce interference. However, beamforming microphone arrays are too large for small form factor products such as smart watches. Yet these small form factor products, which have precious little space for tactile user input (i.e. knobs, buttons and touch screens), would benefit immensely from a user interface based on reliably accurate automatic speech recognition.
This thesis proposes a solution for interference mitigation that employs blind source separation with a compact array of commercially available unidirectional microphone elements. Such an array provides adequate spatial diversity to enable blind source separation and would easily fit in a smart watch or similar small form factor product. The solution is characterized using publicly available speech audio clips recorded for the purpose of testing automatic speech recognition algorithms. The proposal is modelled in different interference environments and the efficacy of the solution is evaluated. Factors affecting the performance of the solution are identified and their influence quantified. An expectation is presented for the quality of separation as well as the resulting improvement in word error rate that can be achieved from decoding the separated speech estimate versus the mixture obtained from a single unidirectional microphone element. Finally, directions for future work are proposed, which have the potential to improve the performance of the solution thereby making it a commercially viable product.
25
Gholami, Mehrdad. "A C-Band Compact High Power Active Integrated Phased Array Transmitter Module Using GaN Technology." Thesis, Université d'Ottawa / University of Ottawa, 2017. http://hdl.handle.net/10393/36045.
Анотація:
In this research, an innovative phased array antenna module is proposed to implement a high-power, high-efficient and compact C-band radio transmitter. The module configuration, which can be integrated into front-end circuits, was designed as planar layers stacked up together to form a metallic cube. The layers were fabricated by using a Computer Numerical Control (CNC) milling machine and screwed together. The antenna parts and the amplifier units were designed at two opposite sides of the cube to spread the dissipated heat produced by the amplifiers and act as a heat sink. Merging the antenna parts with the amplifier circuits offers additional advantages such as decreasing the total power loss, mass, and volume of the transmitter modules by removing the extra power divider and combiner networks and connectors between them as well as reducing the total signal path.
To achieve both a maximum possible radiation efficiency and high directivity, the aperture waveguide antenna was selected as the array element. Four antenna elements have been located in a cavity to be excited equally and the cavity is excited through a slot on its underside so a compact subarray is formed. Antenna measurements demonstrated a 15.5 dBi gain and 20 dB return loss at 10 % fractional bandwidth centered around 5.8 GHz and with more than 98% radiation efficiency. The total dimensions of the subarray are approximately 8*12*4 cm3.
The outcoming signal from the amplifiers is transferred into the slot exciting the subarray through a microstrip-to-waveguide transition (MWT). A novel and robust MWT structure was designed for the presented application. The MWT was also integrated with a microstrip coupler to monitor the power from the amplifier output. The measured insertion loss of the MWT along with the microstrip coupler was less than 0.25 dB along with more than 20 dB return loss within the same bandwidth of the subarray. The microstrip coupler shows 38 dB of coupling and more than 48 dB of isolation with negligible effects on the amplifier output signal and the insertion/return loss of the MWT.
The amplifier subcomponents consist of power combiners/dividers (PCDs), high power amplifiers (HPAs) and bias circuitry. A Monolithic Microwave Integrated Circuit (MMIC) three-stage HPA was designed in a commercially available 0.15 um AlGaN/GaN HEMT technology provided by National Research Council Canada (NRC) and occupies an area of 4.7*3.7 mm2. To stabilize the HPA, a novel inductive degeneration technique was successfully used. To the best of the author’s knowledge, this is the first time this technique has been used to stabilize HPAs. Careful considerations on input/output impedances of all HEMTs were taken into account to prevent parametric oscillations. Other instability sources, i.e. odd-mode, even-mode, and low frequency (bias circuit) oscillations were also prevented by designing the required stabilization circuits. The electromagnetic simulation of the HPA shows 35 W (45.5 dBm) of saturated output power, 26 dB large signal gain and 29% power added efficiency within the same operating bandwidth as the subarray. The output distortion is less than 27 dB, indicating that the HPA is highly linear. The PCD was designed by utilizing a novel, enhanced configuration of a Gysel structure implemented on Rogers RT-Duroid5880. The insertion loss of the Gysel is less than 0.2 dB while return loss and isolation are greater than 20 dB over the entire bandwidth. The same subarray area (8*12 cm2) has been used for the amplifier circuits and up to eight HPAs can be included in each module. All the above parts of the transmitter module were fabricated and measured, except the MMIC-HPA.
26
Liu, Yuanzhi. "Compact Omnidirectional Millimeter-Wave Antenna Array Using Substrate Integrated Waveguide Technique and Efficient Modeling Approach." Thesis, Université d'Ottawa / University of Ottawa, 2021. http://hdl.handle.net/10393/42031.
Анотація:
In this work, an innovative approach for effective modeling of substrate integrated waveguide (SIW) devices is firstly proposed. Next, a novel substrate integrated waveguide power splitter is proposed to feed antenna array elements in series. This feed network inherently provides uniform output power to eight quadrupole antennas. More importantly, it led to a compact configuration since the feed network can be integrated inside the elements without increasing the overall array size. Its design procedure is also presented.
Then, a series feed network was used to feed a novel compact omnidirectional antenna array. Targeting the 5G 26 GHz mm-wave frequency band, simulated results showed that the proposed array exhibits a broad impedance bandwidth of 4.15 GHz and a high gain of 13.6 dBi, which agree well with measured results. Its attractive features indicate that the proposed antenna array is well suitable for millimeter-wave wireless communication systems.
27
Volmer, Christian [Verfasser], Matthias [Akademischer Betreuer] Hein, Reiner [Akademischer Betreuer] Thomä, and Klaus [Akademischer Betreuer] Solbach. "Compact antenna arrays in mobile communications : a quantitative analysis of radiator coupling / Christian Volmer. Matthias Hein. Reiner Thomä. Klaus Solbach." Ilmenau : Universitätsbibliothek Ilmenau, 2010. http://d-nb.info/1001147197/34.
28
Naqiv, Syed Aftab. "A Compact Cylindrical-shape Microstrip Structure with Cloaking Properties for Mutual Coupling Reduction in Array Antennas." Diss., North Dakota State University, 2014. http://hdl.handle.net/10365/24666.
29
Naqvi, Syed Aftab. "A Compact Cylindrical-Shape Microstrip Structure with Cloaking Properties for Mutual Coupling Reduction in Array Antennas." Diss., North Dakota State University, 2014. https://hdl.handle.net/10365/27377.
Анотація:
A cylindrical-shaped microstrip structure with cloaking properties is presented as a shielding device to reduce the mutual coupling between two patch antennas. The surface comprises of a number of 2-port microstrip (2-PM) elements printed on individual substrates and, to enclose a particular region, several 2-PM elements are interconnected into a cylindrical shape. Each 2-PM element has the capability of coupling an incident EM field on the surface to the adjacent interconnected elements. Then, because the 2-PM elements are connected into a cylindrical shape, the incident EM field is re-radiated from the other interconnected 2-PM elements in a direction away from the transmitter; achieving a behavior similar to a cloak. The prototypes in this dissertation illustrates that this surface has the additional benefit of overcoming many of the manufacturing difficulties of traditional cloaks because microstrip structures are used. To demonstrate this concept, a cylindrical surface operating at 3.89 GHz and a frequency reconfigurable surface (consisting of 2-port frequency reconfigurable microstrip elements (2-PFRM)) operating at 3.68 GHz and 3.89 GHz is simulated in HFSS, manufactured and measured in a full anechoic chamber. Moreover, as an application, the cylindrical surface operating at 3.89 GHz is used to reduce the mutual coupling between two patch antennas operating simultaneously at 3.89 GHz. The radiation pattern and the gain of a 2-element array is measured to demonstrate the negligible effects of a cylindrical surface on the far field antenna array parameters. Simulation and measurement results are in good agreement and validate the proposed EM cloak-based surface for applications such as antenna array shielding, radar cross section and communications in complex EM environments.
30
Rosette, Keith Andrew. "Investigation of a compact acoustic source array for the active control of aircraft engine fan noise." Thesis, This resource online, 1994. http://scholar.lib.vt.edu/theses/available/etd-12302008-063020/.
31
Farjam, Aslan. "Influence of Alumina Addition to Aluminum Fins for Compact Heat Exchangers Produced by Cold Spray Additive Manufacturing." Thesis, Université d'Ottawa / University of Ottawa, 2015. http://hdl.handle.net/10393/33383.
Анотація:
Aluminum and aluminum-alumina powder mixtures were used to produce pyramidal fin arrays on aluminum substrates using cold spray as an additive manufacturing process. Using aluminum-alumina mixtures instead of pure aluminum powder could be seen as a cost-effective measure, preventing nozzle clogging. The fin geometries that were produced were observed using a 3D digital microscope to determine the flow passages width and fins geometric details. Heat transfer and pressure tests were carried out using different ranges of appropriate Reynolds numbers for the sought commercial application to compare each fin array and determine the effect of alumina content. It was found that the presence of alumina reduces the fins’ performance when compared to pure aluminum but that they still outperform traditional fins. Numerical simulations were performed and were used to explain the obtained experimental results. The numerical model opens up new avenues in predicting different parameters such as pressure and substrate temperature.
32
Westrick, Michael A. "Compact Wire Antenna Array for Dedicated Short-Range Communications: Vehicle to Vehicle and Vehicle to Infrastructure Communications." University of Toledo / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1345081406.
33
Roberts, Adam Kaleo. "Improvements, Algorithms and a Simulation Model for a Compact Phased-Array Radar for UAS Sense and Avoid." BYU ScholarsArchive, 2017. https://scholarsarchive.byu.edu/etd/6314.
Анотація:
Unmanned aerial systems (UAS) are an influential technology which can enhance life in multiple ways. However, they must be able to sense and operate safely with manned aircraft. Radar is an attractive sensor for UAS because of its all-weather performance. It is challenging, though, to meet the size, weight, and power (SWaP) limitations of UAS and especially small-UAS while still maintaining the needed sensing capability. A working FMCW radar prototype has been created which meets the SWaP requirement of small-UAS. A simulation model for the radar was developed to test the processing algorithms of the radar and proved to be advantageous in that purpose. An automatic target detection algorithm was also successfully developed to allow the radar to identify targets of interest in a cluttered and dynamic environment. Fixed-wing airborne tests have been performed with the radar which show that the radar meets the SWaP requirements of small-UAS. They also show the prototype requires a higher sensitivity to detect other small-UAS. A successful redesign of the radar's receivers was done to make the radar more sensitive.
34
Wang, Kun [Verfasser], Thomas [Akademischer Betreuer] Eibert, and Wolfgang [Akademischer Betreuer] Menzel. "Investigations on Compact Antenna Arrays for Multiple Input Multiple Output Communication Systems / Kun Wang. Betreuer: Thomas Eibert. Gutachter: Thomas Eibert ; Wolfgang Menzel." München : Universitätsbibliothek der TU München, 2016. http://d-nb.info/1081768002/34.
35
Pralon, Mariana Verfasser], Reiner [Akademischer Betreuer] [Thomä, Matthias [Gutachter] Hein, and José Richardo [Gutachter] Bergmann. "Compact antenna arrays for efficient direction of arrival estimation / Mariana Pralon ; Gutachter: Matthias A. Hein, José Richardo Bergmann ; Betreuer: Reiner S. Thomä." Ilmenau : TU Ilmenau, 2017. http://d-nb.info/1178142310/34.
36
Butt, Safwat Irteza [Verfasser], Matthias [Akademischer Betreuer] Hein, Reiner S. [Gutachter] Thomä, and Achim [Gutachter] Dreher. "Compact adaptive planar antenna arrays for robust satellite navigation systems / Safwat Irteza Butt ; Gutachter: Reiner S. Thomä, Achim Dreher ; Betreuer: Matthias Hein." Ilmenau : TU Ilmenau, 2016. http://d-nb.info/1178166546/34.
37
Butt, Safwat Irteza [Verfasser], Matthias [Akademischer Betreuer] Hein, Reiner [Gutachter] Thomä, and Achim [Gutachter] Dreher. "Compact adaptive planar antenna arrays for robust satellite navigation systems / Safwat Irteza Butt ; Gutachter: Reiner S. Thomä, Achim Dreher ; Betreuer: Matthias Hein." Ilmenau : TU Ilmenau, 2016. http://nbn-resolving.de/urn:nbn:de:gbv:ilm1-2016000659.
38
Pralon, Mariana [Verfasser], Reiner [Akademischer Betreuer] Thomä, Matthias [Gutachter] Hein, and José Richardo [Gutachter] Bergmann. "Compact antenna arrays for efficient direction of arrival estimation / Mariana Pralon ; Gutachter: Matthias A. Hein, José Richardo Bergmann ; Betreuer: Reiner S. Thomä." Ilmenau : TU Ilmenau, 2017. http://d-nb.info/1178142310/34.
39
Almeida, Filho Valdez Arag?o de. "Arranjos Log-Peri?dicos Compactos em Microfita com Elementos Fractais de Koch." Universidade Federal do Rio Grande do Norte, 2010. http://repositorio.ufrn.br:8080/jspui/handle/123456789/15315.
Анотація:
Made available in DSpace on 2014-12-17T14:55:43Z (GMT). No. of bitstreams: 1
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Previous issue date: 2010-06-14Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior
This work aims to present how the application of fractal geometry to the elements of a log-periodic array can become a good alternative when one wants to reduce the size of the array. Two types of log-periodic arrays were proposed: one with fed by microstrip line and other fed by electromagnetic coupling. To the elements of these arrays were applied fractal Koch contours, at two levels. In order to validate the results obtained some prototypes were built, which were measured on a vector network analyzer and simulated in a software, for comparison. The results presented reductions of 60% in the total area of the arrays, for both types. By analyzing the graphs of return loss, it was observed that the application of fractal contours made different resonant frequencies appear in the arrays. Furthermore, a good agreement was observed between simulated and measured results. The array with feeding by electromagnetic coupling presented, after application of fractal contours, radiation pattern with more smooth forms than the array with feeding by microstrip line
Este trabalho tem como objetivo apresentar como a aplica??o de contornos fractais aos elementos de um arranjo log-peri?dico se torna uma alternativa bastante interessante quando se deseja reduzir as dimens?es do arranjo. Foram propostos dois tipos de arranjos log-peri?dicos: um com alimenta??o por linha de microfita e outro com alimenta??o por acoplamento eletromagn?tico. Aos elementos desses arranjos foram aplicados contornos fractais de Koch, em dois n?veis. Com a finalidade de validar os resultados obtidos foram constru?dos prot?tipos, que foram caracterizados experimentalmente em um analisador de rede vetorial e simulados em software, para compara??o. Os resultados mostraram redu??es de 60% nas dimens?es dos arranjos, para ambos os tipos. Atrav?s da an?lise dos gr?ficos da perda de retorno, p?de-se observar que a aplica??o dos contornos fractais fez com que aparecessem diferentes frequ?ncias de resson?ncia nos arranjos. Al?m disso, observa-se uma boa concord?ncia entre os resultados medidos e simulados. O arranjo com alimenta??o por acoplamento eletromagn?tico apresentou, ap?s aplica??o dos contornos fractais, menores valores de diretividade do que o arranjo com alimenta??o por linha de microfita
40
Ibraheam, Maysam [Verfasser], Matthias [Akademischer Betreuer] Hein, Reiner [Gutachter] Thomä, and Michael [Gutachter] Meurer. "Design and testing of compact dual-band dual-polarized robust satellite navigation antenna arrays / Maysam Ibraheam ; Gutachter: Reiner Thomä, Michael Meurer ; Betreuer: Matthias Hein." Ilmenau : TU Ilmenau, 2020. http://d-nb.info/1210861771/34.
41
Cormier, Yannick. "Performance, Manufacturability and Mechanical Properties of Near-Net Shaped Pyramidal Fin Arrays for Compact Heat Exchangers Produced Using Cold Spray as an Additive Manufacturing Technique." Thesis, Université d'Ottawa / University of Ottawa, 2016. http://hdl.handle.net/10393/34981.
Анотація:
Significant efforts have been made in the last decades to decrease the world’s dependency to fossil fuels. One of the fronts which has shown major improvement is gas turbine efficiency. To this end, components such as recuperators have been developed to recover heat that is usually trapped and wasted in the exhaust gases of combustion processes. Brayton Energy Canada has recently developed a promising compact heat exchanger that could be used as a recuperator in gas turbines. Nevertheless, this novel type of wire mesh heat exchanger still has room for improvement, especially regarding the way that its fin arrays are manufactured due to the fact that the technique presently used is time consuming and consequently costly. The present research aims to manufacture near-net shaped pin fin arrays using cold gas dynamic spray as an additive manufacturing technique by selectively covering the substrate by the means of a mask.
Moreover, this research work studies the feasibility of using CGDS as an additive manufacturing technique to produce pin fin arrays, the thermal and hydrodynamic performances of this new type of pin fin created, the effect of geometric parameters such as fin density and height on the performances, the viability of the sprayed pin fins in a real environment by means of finding mechanical properties such as adhesion strength, the possibility of producing a streamwise material anisotropic fin arrays, and finally the different adhesion mechanisms by means of numerical modeling of the relevant impact physics.
42
Harding, Matthew T. "An experimental investigation of the performance of staggered PIN-FIN Array laminar flow heat exchangers." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2005. http://library.nps.navy.mil/uhtbin/hyperion/05Mar%5FHarding.pdf.
43
Clauzier, Sébastien. "Conception et réalisation d'antennes intégrables en mâture pour les plateformes navales : applications aux communications V/UHF et à un radar de navigation à balayage électronique en bande X." Thesis, Rennes 1, 2013. http://www.theses.fr/2013REN1S067.
Анотація:
En raison des conflits maritimes qui s'étendent (piraterie, embargo,...), les besoins de communiquer et de détecter les menaces sont de plus en plus importants. Ceci conduit irrémédiablement à l'augmentation du nombre d'aériens à bord des plateformes navales. Afin de gérer au mieux cet accroissement du nombre d'antennes, qui conduit à des effets de couplage et à une augmentation de la signature radar du navire, les principales entreprises du secteur ont mis en place des structures de mâts intégrés. C'est dans un contexte d'amélioration de leur mâture intégrée compacte (Cmast™) que les Constructions Mécaniques de Normandie (CMN) de Cherbourg en collaboration avec l'IETR de Rennes et INEO Défense ont proposé cette thèse. Ces travaux ont pour objectifs le développement de deux systèmes antennaires intégrables au sein de cette mâture intégrée compacte : une antenne de communication en bande V/UHF et une antenne de radar de navigation à balayage électronique en bande X. Une première étude a permis le développement d'une antenne conique large bande (225-400MHz) dont les paramètres géométriques ont été optimisés pour assurer une communication entre les navires et des aéronefs. Un prototype de cette antenne a été réalisé et a permis une validation expérimentale de ses performances. Une seconde étude a permis le développement d'une antenne d'un radar de navigation à balayage électronique en bande X. Cette antenne est basée sur une technologie transmit-array comprenant une source illuminante et un réseau permettant la formation du diagramme. Un effort particulier a été porté sur la source illuminante qui doit éclairer, à des distances très courtes (<550mm), un réseau qui présente des dimensions particulières (1530mmx100mm). Plusieurs sources utilisant un principe de focalisation en zone champ proche ont été développées et validées expérimentalement. Enfin deux architectures d'antennes transmit-array ont été étudiées, utilisant respectivement une technologie imprimée et une technologie en guide. Le fonctionnement de l'antenne complète (source illuminante + réseau transmit-array) a été étudié théoriquementThe need to communicate and detect potential enemies increases with the extension of maritime conflicts. This need impacts directly the number of antennas on naval platforms. However, this increase of aerials leads to several damaging effects: like coupling or high radar signature. To limit this effect, some companies have developed integrated mast design. This structure limits the coupling effect between aerials by a subdivision of the mast and provides an omnidirectional coverage for all antennas inserted inside the mast. The objective of the thesis is to design two antenna systems for the compact integrated mast (CmastTM) developed by the Constructions Mécanique de Normandie (CMN): a communication antenna in the V/UHF band and an electronically scanning antenna for a maritime navigation radar in X-band. For the communication in the V/UHF band, a broadband conical antenna has been developed (225-400MHz). This antenna provides an optimized radiation pattern to insure the communications between the ship and the aircrafts. An experimental validation has been done with a prototype. In the second study, we have developed an electronically scanning antenna for a navigation radar. This antenna is based on a transmit-array technology including an illuminating feed and an antenna which generates the appropriate radiation pattern. A large part of the study has been done on the feed, which illuminates an array with specific dimensions (1530mmx100mm). Three different near-field focusing feeds have been developed and some of them have been validated experimentally. Then, two architectures of transmit-array antennas have been studied, using two different technologies: printed technology and a mixed technology with waveguide and horn
44
Öztezel, Aslihan. "Le réexamen d'une décision pénale consécutif à un arrêt de la Cour Européenne des Droits de l'Homme, en droit français et turc comparés." Thesis, Université de Lorraine, 2013. http://www.theses.fr/2013LORR0094/document.
Анотація:
Les pays fondateurs du Conseil de l'Europe, en signant le 4 novembre 1950, à Rome, la Convention de Sauvegarde des Droits de l'Homme et des Libertés Fondamentales ignoraient sans doute qu'ils changeaient fortement l'avenir de leur pays et qu'un retour en arrière n'était guère possible. L'instauration de l'ordre européen a été accomplie par la jurisprudence de la Cour Européenne des Droits de l'homme (Cour EDH), suivant l'accession de la requête individuelle. Le système européen, brodé par les pays membres et évolué avec leurs violations, n'a jamais été aussi secoué que par la demande de la Cour EDH du réexamen d'une décision pénale suivant son arrêt. Le réexamen d'une décision pénale consécutif à un arrêt de la Cour EDH constitue une des rares changements qu'exige le système européen sur les droits internes des Etats membres. L'instauration du réexamen suite aux arrêts de la Cour EDH a suivi une voie différente dans chaque État membres. Dans le cas de la France et la Turquie, la voie d'instauration était difficile. En Turquie, les discussions ont tourné autour de la politique tandis qu'en France c'était plutôt l'autorité de la chose jugée qui avait été mise en valeur contre cette nouvelle voie de recours. C'est pour ce là d'ailleurs, ces deux pays ont longtemps hésité à instaurer cette voie de recours dans leur droit interne. Les modifications qui ont eu lieu en France et en Turquie ont eu des dynamiques différentes mais les deux pays ont vécu les mêmes bouleversements sur la détermination des législateurs et la fidélité aux normes du système européen. Le réexamen n'a pas seulement changés les droits internes des pays membres du Conseil de l'Europe. Il a forcé les législateurs à repenser sur leur détermination au système européenne et aux attributions de ce dernier et plus important que tout, il a mis en question les dogmes et les notions constituantes de droit procédure pénale. Partant, il est vrai que le système européen a changé parce que le réexamen a sauvé les arrêts de la Cour EDH condamnant les Etats de rester comme des lettres mortes et a permis au requérant de faire valoir ses droits en droit interneUnavailable
45
Pujol, Hadrien. "Antennes microphoniques intelligentes : localisation de sources acoustiques par Deep Learning." Thesis, Paris, HESAM, 2020. http://www.theses.fr/2020HESAC025.
Анотація:
Pour ma thèse de doctorat, je propose d’explorer la piste de l’apprentissage supervisé, pour la tâche de localisation de sources acoustiques. Pour ce faire, j’ai développé une nouvelle architecture de réseau de neurones profonds. Mais, pour optimiser les millions de variables d’apprentissages de ce réseau, une base de données d’exemples conséquente est nécessaire. Ainsi, deux approches complémentaires sont proposées pour constituer ces exemples. La première est de réaliser des simulations numériques d’enregistrements microphoniques. La seconde, est de placer une antenne de microphones au centre d’une sphère de haut-parleurs qui permet de spatialiser les sons en 3D, et d’enregistrer directement sur l’antenne de microphones les signaux émis par ce simulateur expérimental d’ondes sonores 3D. Le réseau de neurones a ainsi pu être testé dans différentes conditions, et ses performances ont pu être comparées à celles des algorithmes conventionnels de localisation de sources acoustiques. Il en ressort que cette approche permet une localisation généralement plus précise, mais aussi beaucoup plus rapide que les algorithmes conventionnels de la littératureFor my PhD thesis, I propose to explore the path of supervised learning, for the task of locating acoustic sources. To do so, I have developed a new deep neural network architecture. But, to optimize the millions of learning variables of this network, a large database of examples is needed. Thus, two complementary approaches are proposed to constitute these examples. The first is to carry out numerical simulations of microphonic recordings. The second one is to place a microphone antenna in the center of a sphere of loudspeakers which allows to spatialize the sounds in 3D, and to record directly on the microphone antenna the signals emitted by this experimental 3D sound wave simulator. The neural network could thus be tested under different conditions, and its performances could be compared to those of conventional algorithms for locating acoustic sources. The results show that this approach allows a generally more precise localization, but also much faster than conventional algorithms in the literature
46
Pozzobon, Nicola. "A Level 1 Tracking Trigger for the CMS Experiment at the LHC Phase 2 Luminosity Upgrade." Doctoral thesis, Università degli studi di Padova, 2011. http://hdl.handle.net/11577/3422049.
Анотація:
The second decade of Large Hadron Collider operations, from about 2020 onwards, envisages a remarkable increase in collider instantaneous luminosity, one order of magnitude above the project one. This luminosity increase presents several challenges to the LHC experiments. The present Tracker of the Compact Muon Solenoid experiment must be replaced with a system providing excellent tracking quality at higher luminosities, as well as Tracking Trigger inputs to the existing "Level 0" CMS Trigger system at the full 40 MHz bunch-crossing rate. The minimal requirements for a Tracking Trigger would be the capability to confirm the presence of high-pT tracks associated with Calorimeter and/or Muon Level 0 Triggers. The ability to provide effective isolation criteria may also be required, and would in any case substantially improve the Trigger performance.
Maintaining the data rates generated by Tracking Trigger inputs within a manageable bandwidth requires sensor modules able to locally sparsify the data. Measuring at detector module level the track direction in the transverse plane, and hence deriving its transverse momentum, is the most promising solution to provide such a detector-embedded data reduction feature. These so-called "pT-modules"' would only transmit to the Level 1 Trigger "stubs", pairs of correlated hits in two closely separated sensors, derived by tracks with pT above a given threshold. To exemplify, a 2 GeV/c threshold would cut data rate of more than a factor 10, hence providing a data rate well within the capabilities of present data links.
The pT-modules design discussed in this work consists of two, closely spaced segmented silicon sensors, featuring both pattern hit correlation across the module and a single hit position resolution high enough to compute stubs with the required accuracy to resolve track directions despite a lever arm of about only 1 mm. A concept Tracker layout, the so-called "Long Barrel", consisting in an Outer Tracker completely built out of pT-modules, has been proposed. The Long Barrel Tracker is particularly flexible in simulation studies of Tracking Trigger as it allows for information from several layers of the Tracker to be combined in a projective geometry. For this reason, it is meant as a testing ground to compare the performance of different designs and configurations. The Long Barrel layout also allows the generation of even more structured Trigger Objects such as "tracklets", consisting of pairs of stubs in opportunely paired layers, which can in turn be used as seeds to generate "Level 1 tracks", including even more stubs.
The choice of stacked sensors for pT-modules has been recently strengthened by test beam results obtained with novel prototypes of Monolithic Active Pixel Sensors and reported in this thesis. The developement of Tracking Trigger simulations is also presented as a major step towards the design of a realistic Trigger capable Tracker upgrade. A particular challenge for the Trigger system is given by tau leptons produced in many rare processes searched at the LHC. The performance of a Tracking Trigger on final states with tau leptons will be crucial at very high luminosities and is presented at the and of this document as the natural step forward in the work on the subject.Durante il secondo decennio di operazioni al Large Hadron Collider, a partire dall'anno 2020, è previsto un notevole aumento della luminosità istantanea del collisionatore, di un ordine di grandezza superiore rispetto a quella di progetto. Questa luminosità presenta numeose sfide per gli esperimenti a LHC. Il Tracciatore attualmente impiegato nell'esperimento Compact Muon Solenoid dovrà essere rimpiazzato con un sistema in grado di garantire una tracciatura di qualità eccellente ad alte luminosità e, allo stesso tempo, fornire informazioni utili per l'attuale "Livello 0" del sistema di Trigger a CMS, alla frequenza di collisioni di 40 MHz. Le richieste minime per un Trigger basato sul Tracciatore sono la capacità di confermare la presenza di tracce ad alto pT associate a Trigger di Livello 0 ottenuti con i Calorimetri o i rivelatori di muoni. La capacità di fornire criteri efficaci di isolazione può essere ulteriormente richiesa e in ogni caso migliorerebbe significativamente le prestazioni del Trigger. Il rateo dei dati associati con la generazione nel Tracciatore di informazione di Trigger può essere mantenuto in una larghezza di banda sufficientemente maneggevole richiedendo che i moduli sensitivi siano in grado di ridurre localmente i dati. I principali candidati per una simile riduzione locale del rateo i dati sono caratterizzati dalla capacità di fornire la direzione della traccia nel piano trasverso, oltre alla sua posizione, da cui poter dedurre la quantità di moto della traccia stessa. Questi "pT-modules" trasmetterebbero di conseguenza al Trigger di primo livello degli abbozzi di traccia ("stub") generati da particelle con pT al di sopra di 2 GeV/c. La scelta di una simile soglia permetterebbe la riduzione dei dati di un fattore superiore a 10, consentendo quindi un rateo facilmente tollerabile. I moduli di Trigger possono essere realizzati con due sensori di silicio paralleli leggermente separati, caratterizzati da una risoluzione sulla misura del singolo punto d'impatto tale che gli stub, ottenuti tramite correlazione tra i punti misurati nel modulo, possano fornire un'adeguata misura della direzione della traccia, nonostante il braccio di leva sia dell'ordine del millimetro. Un'ipotetica configurazione per il Tracciatore, composto da "lunghi barili", che prevede un Tracciatore esterno realizzato totalmente con moduli di Trigger, è stata proposta. Essa è particolarmente flessibile negli studi di simulazione per il Trigger realizzato con il Tracciatore giacché consente di combinare tra loro, tramite proiezioni geometriche, le informazioni provenienti da diversi strati del Tracciatore. Pertanto è un campo di prova per confrontare le prestazioni di diverse concezioni e diverse configurazioni. Il Tracciatore proposto permette anche la generazione di oggetti più articolati degli stub per il Trigger, come ad esempio le "tracklet", che consistono in coppie di stub opportunamente associate tra loro, le quali possono a loro volta essere usate come punto di partenza per la costruzione di Tracce di Primo Livello. La scelta di moduli di Trigger realizzati con sensori accoppiati è rafforzata da risultati recenti ottenuti con dei prototipi innovativi di rivelatori a Pixel Monolitici durante dei test sotto fascio riportati in questa tesi. Lo sviluppo di simulazioni per un Trigger con il Tracciatore è anch'esso presentato come un significativo progresso verso la progettazione di un nuovo Tracciatore realistico e capace di fornire informazioni utili per il Trigger. Particolarmente impegnativo è lo sforzo per un Trigger che selezioni i leptoni tau prodotti in numerosi processi rari di interesse per gli esperimenti a LHC. Le prestazioni di un Trigger con il Tracciatore su stati finali contenenti leptoni tau saranno fondamentali a luminosità molto elevate e sono illustrate alla fine di questo documento, come naturale prosecuzione del lavoro descritto.
47
Fang, Han-Sheng, and 方瀚陞. "Decoupling of Compact Multiple Antenna Arrays Using Cancellation Technique." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/pv5k8f.
Анотація:
博士國立臺北科技大學
電子工程系博士班
105
A cancellation technique that not only can achieve better isolation but has also wide usability for any multiple antennas, is proposed in this dissertation. The technique involves the model construction of multiple antennas including the calculation of the required be cancelled energy in the decoupling process and correcting the impedance matching of each port to accomplish the decoupling of multiple antenna arrays. In order to verify the effect of this cancellation technique, this dissertation presents a quad-antenna array with cancellation technique that is derived from a single antenna structure with a step-by-step illustrates process for proper design. Finally, MIMO performance of the multiple antennas is assessed through the evaluated and measured branch power ratio, envelope correlation coefficient, and the diversity gain. The results showed that when compared with the dual-antenna array, the dual-antenna array implemented with cancellation technique has the envelope correlation coefficient that is lowered by 0.43 and has an enhanced diversity gain higher by 3.5 dB. Next, comparing with the quad-antenna array show that implementing with cancellation technique has the envelope correlation coefficient that lowered by 0.4 and diversity gain higher by 6.5 dB. Therefore, the proposed cancellation technique can be used to achieve better MIMO performance in compact multiple antennas.
48
"Coupled resonator decoupling networks for compact antenna arrays of advanced communication systems." 2014. http://repository.lib.cuhk.edu.hk/en/item/cuhk-1290678.
Анотація:
Developements in next-generation advanced communication systems and devices have triggered multi-antenna systems for improved data throughput and transmission reliability. According to Shannon's theorem, to improve the channel capacity of a communication system, one method is to broaden the system bandwidth. Another method is to use the multiple-input-multiple-output (MIMO) technology. This technology uses multiple antennas at both transmitter and receiver to improve the channel capacity by several folds. Therefore, compact and broadband multi-antenna systems are very promising for future high-capacity wireless communication systems.In parallel to advances in MIMO technologies, there is an irreversible trend that more and more communication protocols together with their respective antennas and radio transceivers are integrated into one compact unit. The radio systems of different protocols may work in very closely adjacent frequency bands or even overlapped bands. The coexistence of these multiple antennas has also become a concern from both industry and academic communities.
However, since the number of antenna elements is increasing in more and more compact devices, the physical limitation on inter-element spacing cannot be easily transcended, which will lead to destructive mutual coupling interference as well as pattern/spatial dependent correlation. In a multi-antenna system, the signals at all antenna ports are coded differently either to increase the packet rate or simply because that they belong to different radio transceivers. If unwanted signals are coupled to the ports, the signal-to-noise ratio will be deteriorated. Furthermore, the far-field patterns of closely spaced antennas are highly correlated and the signal envelope correlation will become significantly large. All these negative impacts will greatly diminish the channel capacity and the data throughput. Such drawbacks restrain the use of multiple antenna systems. It is therefore vital to develop a simple, broadband and effective decoupling technique for compact multiple antenna systems/arrays in advanced communication systems.
The major objectives of this thesis are (1) to innovate a new antenna decoupling technique called shunt type of coupled resonator decoupling networks (S-CRDNs) for wireless mobile terminal antennas; (2) to develop the synthesis theory and the design methodologies of the shunt type of CRDNs (S-CRDN) for various of antenna arrays; (3) to extend the theory and the design concept to dual band S-CRDNs, three port S-CRDNs and a LTCC S-CRDN module for mobile terminal applications; (4) to develop a cascaded type of coupled resonator decoupling networks (C-CRDN) for base station and wireless routers antennas; (5) to innovate a novel decoupling technique for multiple element antenna arrays with dummy antennas arrays; and more importantly, (6) to explore innovative applications with experimentally verified superiority.
Based on the characteristics of the coupled antennas, the synthesis theory of S-CRDNs starts from a set of required admittance polynomials, the targeted coupling matrix can be obtained from the polynomials analytically for a second-order S-CRDN. Possible coupling topologies of S-CRDNs include, but not limited to, a second-order all pole S-CRDN, a second-order S-CRDN with source-load coupling, a high-order S-CRDN network for dual band applications and a three port S-CRDN for three-element antenna arrays. Moreover, the concept of a “one-fit-all” S-CRDN module base on LTCC technology is also proposed and investigated, which makes an integrated S-CRDN module antenna independent as long as the frequency range matches.
The general theory of C-CRDN is developed in this thesis based on the circuit model of a 4-port coupled resonators network, which is proposed to solve the antenna decoupling problem between two base station antennas, to which a high level of isolation between two adjacent frequency bands is required, for the first time. This type of CRDN is particularly useful when one antenna transmitting very high power energy in a vicinity to a receiver antenna that works in an adjacent frequency band with very high sensitivity.
A decoupling technique with appropriately designed dummy elements and their passive complex loading is also proposed in this thesis. The technique employs the characteristics of non-radiating antenna elements (dummy elements). Multiple dummy elements can be introduced to alter the mutual coupling characteristic the radiating antennas in the original compact array. Therefore, this technique is more suitable for decoupling problem of an array with multiple elements. It is demonstrated that for a four-element compact array, four dummy elements are sufficient to decouple the four radiating elements in a broadband sense. Additionally, each radiating element can be independently matched. This decoupling technique can be extended to antenna arrays with a high number of radiating elements.
Finally, necessary and important figures of merit for benchmarking a multiple element antenna array are introduced. Prototypes of multi-antenna systems with and without using proposed decoupling techniques are fabricated, measured and compared. A large number of experimental results have demonstrated the superiority and the significance of the proposed decoupling techniques for compact antenna arrays of advanced wireless communication systems.
下一代無線通訊系統與設備的飛速發展，極大的促進了多天線系統的開發與應用。多天線系統天生具有高數據吞吐率，并能夠確保傳輸的穩定性。根據香農定律，若想要提高一個系統的信道容量，要麼可以展寬系統帶寬，要麼可以適用多輸入多輸出（MIMO）系統。MIMO技術在發射端和接收端安置多個天線，以同時發送多路數據，大大提高了數據的吞吐率和信道容量。理想的狀態下，信道容量隨著收發天線的個數可以線性成倍增加。因此，新一代的小型化多天線系統正在成為未來發展的趨勢。
與此同時，現今無線通訊系統的發展趨勢越來越朝著小型化，集成化以及多功能化發展。這就意味著，越來越多的通信協議及其收發機和天線，將會集成到一個越來越小的終端設備上。另外由於頻譜資源的稀缺，這些共同工作的系統的頻帶越來越寬，頻帶之間的距離也越來越近。這些多天線的共存問題，也日益成為學術界和工業界關心的焦點問題。
但是，當終端的尺寸越來越小，而天線的個數越來越多的時候，天線之間的物理距離這個瓶頸是無法逾越的。如此受限的距離，不但造成了天線之間的相互干擾較大，也造成了他們方向圖和信道的強相關。在多天線系統中，各個天線處的信號編碼是不同的（包括提高數據速率和提高通信可靠性兩種不同的模式）。如果無用的信號耦合到了不該到的端口或者天線處，就會極大的影響信噪比和通信質量。另外，如果多天線的方向圖和信道是相關的話，信號的包絡相關性就會變得異常的大。這些都是嚴重影響多天線系統的性能的因素。因此，設計一種簡單的，寬帶的，有效的解耦技術，對於多天線系統是至關重要的。
本論文的主要目標是：（1）開發一種新的天線解耦技術，叫做並聯型耦合諧振腔解耦網絡，專門針對手機終端。（2）研究針對此解耦網絡的綜合設計手段，以針對不同的多天線陣列，都能有效的設計。（3）將此技術推廣到雙頻，多頻，多端口的多天線系統中。并研究利用低溫共燒陶瓷技術實現此類器件的小型化。（4）開發另一種級聯型耦合諧振腔解耦網絡，專門針對基站和路由器應用。（5）開發一種利用“假”天線進行解耦的新型技術。更重要的是（6）在實際使用場景中驗證所提出的各種解耦技術的有效性。
並聯型耦合諧振腔解耦網絡的綜合方法，需要受限根據耦合天線的特性和參數，得到一組電抗多項式，對於二階的網絡，所需要的耦合係數可以有這些多項式解析得到。實際上，並聯型耦合諧振腔解耦網絡的拓撲結構是多樣的，其中包括：兩階無交叉耦合型，兩階有交叉耦合及源負載耦合型，高階針對多頻的網絡以及三端口的網絡，專門針對三單元天線陣列。從並聯型耦合諧振腔解耦網絡，可以衍生出一種非常重要的基於低溫共燒陶瓷技術的“全能型”解耦網絡。這種網絡在頻率確定的情況下，可以適應各種不同的天線形式和耦合，非常適合在手機終端上廣泛採用。
本論文還討論了針對級聯型耦合諧振腔解耦網路的一般理論，以及其對應的電路模型和網絡參數。這種類型的網絡非常適合解決需要極高隔離度的基站天線解耦問題。這種網絡在本文中是業界首次提出的針對發射天線對領進頻帶接收機強幹擾的微波無緣網絡解決方案。
另外，一種採用“假”天線配合其電抗負載進行解耦的方法也將在文中提到。這種技術利用了並不輻射的“假”天線的寄生特性，通過引入若干不同空間排布的假天線陣，來解決原有天線陣的強互耦問題。這種方法的優越性是可以針對多種不同單元數和不同陣列排布的陣列。
最後，本文將會一一討論多種評估多天線系統性能指標的參數。包括隔離度，效率，包絡相關性，信道容量乃至吞吐率。作為比較，多種多天線系統，包括採用解耦網絡技術和不採用解耦網路技術的天線陣的各種性能參數，都在文中做了詳細比較。大量的實驗證明了採用解耦網絡的多天線系統的優越性。
Zhao, Luyu.
Thesis (Ph.D.)--Chinese University of Hong Kong, 2014.
Includes bibliographical references.
Abstracts also in Chinese.
Title from PDF title page (viewed on 26, October, 2016).
Detailed summary in vernacular field only.
Detailed summary in vernacular field only.
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Su, Feng-Yi, and 蘇峰毅. "Novel compact MIMO antenna arrays with port decoupling and high efficiency." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/q28ceq.
50
Huang, Po-Chung, and 黃柏彰. "Bio-inspired compact camera using curved microlens array." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/60969823444021845310.
Анотація:
碩士國立臺灣大學
光電工程學研究所
101
The human eye has simple structure, high resolution but curved retina. On the other hand, the compound eye has wider field of view but low resolution. In this thesis, we proposed a camera lens design combining with the principle of the insect compound eye and the human eye, simulating the compound eye structure by the microlens array and using two main lenses to simulate human’s lens. This system maintains the advantages and removes the shortcomings of the two structures. Comparing with the mobile phone camera lens with more than five lenses structure and limited field angle, this design contains 6.2 mm × 4.6 mm image plane size with small thickness (5 mm); large field of view (120°