An antenna array is an indispensable portion of a direction-of-arrival (DOA) estimation operation. A number of error sources in the arrays degrade the DOA estimation accuracy. Mutual coupling effect is one of the main error sources and should be corrected for any antenna array. In this thesis, a system theoretic approach is presented for mutual coupling characterization of antenna arrays. In this approach, the idea is to model the mutual coupling effect through a simple linear transformation between the measured and the ideal array data. In this context, a measurement reduction method (MRM) is proposed to decrease the number of calibration measurements. This new method dramatically reduces the number of calibration measurements for omnidirectional antennas. It is shown that a single calibration measurement is sufficient for uniform circular arrays when MRM is used. The method is extended for the arrays composed of non-omnidirectional (NOD) antennas. It is shown that a single calibration matrix can not properly model the mutual coupling effect in an NOD antenna array. Therefore, a sectorized calibration approach is proposed for NOD antenna arrays where the mutual coupling calibration is done in angular sectors. Furthermore, mutual coupling problem is also investigated for antenna arrays over a perfect electric conductor plate. In this case, reflections from the plate lead to gain/phase mismatches in the antenna elements. In this context, a composite matrix approach is proposed where mutual coupling and gain/phase mismatch are jointly modelled by using a single composite calibration matrix. The proposed methods are evaluated over DOA estimation accuracies using Multiple Signal Classification (MUSIC) algorithm. The calibration measurements are obtained using the numerical electromagnetic simulation tool FEKO. The evaluation results show that the proposed methods effectively realize the mutual coupling calibration of antenna arrays.

Array antennas are used extensively in remote sensing applications, where a highly directive beam is needed to scan a particular area of interest on the surface of the earth. The research presented here focuses on the design of different microstrip patch antenna arrays to be used in environmental sensing applications in the X and Ka frequency bands, such as measurements in Snow and Cold Land Processes (SCLP) to detect snow accumulation, snow melt, etc. The goal of this research is to produce highly integrated, low loss, and compact size antenna arrays, while maintaining low power consumption. Multilayer organic (MLO) System-on-a-Package (SOP) technology, using laminates such as Liquid Crystal Polymer (LCP) and RT/Duroid®, provides a lightweight and low cost 3D solution for the fabrication of the antenna arrays. The elements of the antenna arrays are rectangular patches. Two feeding mechanisms, aperture coupling and via feed, were implemented and compared. For the RF distribution network and interconnects, a corporate feed approach was used with reactive T-junctions, Wilkinson dividers, or both, for power division. The feed networks were designed using microstrip. The basic multilayer antenna array design consists of 3 layers of cladded laminate material. The metal layers are as follows: 1) patch antennas, 2) ground plane, 3) feed network, and 4) surface-mount components. The surface mount components would include LNA, PA, TR switch and phase shifter.

Η διπλωματική εργασία περιλαμβάνει τη μελέτη αλλά και την προσομοίωση ευφυούς κεραίας για την υποστήριξη εξειδικευμένων επικοινωνιακών υπηρεσιών και χωρίζεται σε έξι κυρίως κεφάλαια. Το 1ο κεφάλαιο αναλύει τις τεχνικές παραμέτρους των συστοιχιών κεραίας που είναι απαραίτητες για τη μελέτη. Στο 2ο κεφάλαιο γίνεται μια σε βάθος ανάλυση του κυψελοειδούς συστήματος κινητής επικοινωνίας και διακρίνουμε την περίπτωση του στατικού φωτισμού και της κεραιοσυστοιχίας που περιστρέφεται αποτελούμενη από έξυπνες κεραίες. Στο 3ο και στο 4ο κεφάλαιο μέσω διαγραμμάτων ροής (flow charts) δείχνουμε όλες τις απαραίτητες ενέργειες και τα στοιχεία που πρέπει να λάβουμε υπ’ όψιν για το σχεδιασμό και την κατασκευή του αντίστοιχου κεραιοσυστήματος. Στο 5ο κεφάλαιο αναφέρουμε τρόπους κατασκευής μιας συστοιχίας για την κάθε περίπτωση και τα συστατικά μέρη από τα οποία πρέπει να αποτελείται. Τέλος, το 6ο κεφάλαιο περιλαμβάνει γενικά συμπεράσματα και μελλοντικές χρήσεις των ευφυών κεραιών. / This thesis includes the study and simulation of smart antenna in support of specialized communications services, and is divided into six main chapters. The first chapter analyzes the technical parameters of antenna arrays that are needed for the study. In the second chapter is an in-depth analysis of cellular mobile communication system and distinguish the case of static lighting and rotating antenna array consisting of smart antennas. In the 3rd and 4th chapter through flowcharts are shown all the necessary steps and details that must be taken into account for the design and construction of the corresponding antenna system. The 5th chapter addresses how manufacturing an array for each case and the components of which must be composed. Finally, the sixth chapter contains general conclusions and future uses of smart antennas.

Made available in DSpace on 2014-12-17T14:56:02Z (GMT). No. of bitstreams: 1 CiroAPT.pdf: 868504 bytes, checksum: d74079034ebc48de53a5dc4be812ec74 (MD5) Previous issue date: 2003-10-17 / This master dissertation introduces a study about some aspects that determine the aplication of adaptative arrays in DS-CDMA cellular systems. Some basics concepts and your evolution in the time about celular systems was detailed here, meanly the CDMA tecnique, specialy about spread-codes and funtionaly principies. Since this, the mobile radio enviroment, with your own caracteristcs, and the basics concepts about adaptive arrays, as powerfull spacial filter was aborded. Some adaptative algorithms was introduced too, these are integrants of the signals processing, and are answerable for weights update that influency directly in the radiation pattern of array. This study is based in a numerical analysis of adaptative array system behaviors related to the used antenna and array geometry types. All the simulations was done by Mathematica 4.0 software. The results for weights convergency, square mean error, gain, array pattern and supression capacity based the analisis made here, using RLS (supervisioned) and LSDRMTA (blind) algorithms. / Esta disserta??o de mestrado vem trazer um estudo sobre alguns aspectos que influenciam na aplica??o de antenas adaptativas em sistemas celulares DS-CDMA (ou simplesmente CDMA). Foram detalhados alguns conceitos b?sicos a respeito do sistema celular e em geral, bem como sua evolu??o ao longo do tempo, dando ?nfase ? t?cnica CDMA, no que diz respeito aos c?digos de espalhamento e princ?pio de funcionamento. A partir disso, o ambiente de r?dio m?vel, com suas caracter?sticas peculiares, foi abordado, bem como os conceitos b?sicos em que se baseiam o sistema de antenas adaptativas com sua poderosa capacidade de filtragem espacial, capaz de reduzir significativamente o efeito de sinais indesejados. Tamb?m alguns algoritmos adaptativos foram discutidos, esses s?o integrantes do processamento dos sinais captados pelos arranjos, e s?o respons?veis pela atualiza??o dos pesos que de certa forma controlar?o o diagrama de radia??o do arranjo. Mais especificamente, esse trabalho fundamentou-se na an?lise, mediante simula??es computacionais, do comportamento do sistema de antenas adaptativas face ao tipo de antena e ao tipo (geometria) de arranjo empregados. Todas as simula??es foram feitas utilizando o software Mathematica 4.0. Os resultados para a converg?ncia dos pesos, erro m?dio quadr?tico, ganho, diagrama de radia??o e capacidade de supress?o foram as grandezas que basearam as an?lises aqui feitas, utilizando para isso, os algoritmos RLS (supervisionado) e LSDRMTA (cego).

La densification des réseaux allant de pair avec le déploiement de petites cellules, les systèmes Massive MIMO disposent de caractéristiques prometteuses pour accroître la capacité des réseaux au travers des techniques de formation de faisceau, appelées beamforming. Les transmissions aux longueurs d’onde millimétriques (mmWave) sont, quant à elle, très convoitées car, non seulement les bandes passantes exploitables sont extrêmement larges, mais le canal de propagation est principalement Line-of-Sight (LOS), ce qui correspond à la visibilité directe entre le terminal et la station de base. L’attrait que peut avoir un système multi-utilisateurs Massive MIMO à de telles fréquences provient, en partie, du faible encombrement du réseau d’antennes, mais aussi du fort gain de beamforming dont il permet de bénéficier afin de contrecarrer les fortes pertes en espace libre que subissent les signaux à de telles longueurs d’onde. Dans un premier temps nous montrons comment l’augmentation de la fréquence porteuse impacte les performances de deux précodeurs connus. Au travers d’une modélisation déterministe et géométrique du canal, on simule un scénario Outdoor à faible mobilité et à forte densité de population en mettant en avant l’influence du trajet direct et des trajets réfléchis sur les performances. Plus précisément on prouve qu’en configuration purement LOS, le précodeur Zero-Forcing est beaucoup plus sensible à la structure du réseau d’antennes, et à la position des utilisateurs, que le Conjugate Beamforming (aussi connu sous le nom de retournement temporel). On introduit alors un précodeur basé uniquement sur la position angulaire des utilisateurs dans la cellule en référence à la station de base, puis l’on compare ses performances à celles des deux autres. La robustesse d’une telle implémentation à une erreur d’estimation d’angles est illustrée pour un scénario spécifique afin de souligner la pertinence des solutions angulaires, une direction étant plus facile à estimer et son évolution dans le temps plus prévisible.On décrit dans un second temps comment la connaissance des positions angulaires des utilisateurs permet d’accroître la capacité de la cellule par le biais d’un procédé d’allocation de puissance reposant sur une évaluation de l’interférence que chaque faisceau génère sur les autres. On prouve à l’aide de simulations que l’obtention de cette interférence, même exprimée sous une forme très simplifiée, permet d’améliorer très nettement la capacité totale de la cellule. Enfin, nous introduisons les systèmes Hybrides Numériques et Analogiques ayant récemment été proposés afin de permettre à une station de base de conserver un large nombre d’antennes, nécessaire à l’obtention d’un fort gain de beamforming, tout en réduisant le nombre de chaînes Radiofréquences (RF). On commence par décrire une solution permettant à un terminal de former un faisceau dont la direction s’adapte à sa propre inclinaison, en temps réel, pour toujours viser la station de base. On compare ensuite les performances de tels récepteurs, associés à des stations de base Massive MIMO, avec celles d’une solution hybride connue, le nombre de chaînes RF des deux systèmes étant identiques. Principalement, la flexibilité et la capacité d’évolution de ces systèmes est mise en avant, ces deux atouts étant particulièrement pertinents pour de nombreux environnements à forte densité de population. / As wireless communication networks are driven toward densification with small cell deployments, massive MIMO technology shows great promises to boost capacity through beamforming techniques. It is also well known that millimeter-Wave systems are going to be an important part of future dense network solutions because, not only do they offer high bandwidth, but channel is mostly Line-of-Sight (LOS). The attractiveness of using a multi-user Massive MIMO system at these frequencies comes partly from the reduced size of a many antenna base station, but also from the high beamforming gains they provide, which is highly suited to combat the high path losses experienced at such small wavelengths. First we show how raising the carrier frequency impacts the performance of some linear precoders widely used in Massive MIMO systems. By means of a geometrical deterministic channel model, we simulate a dense outdoor scenario and highlight the influence of the direct and multi-paths components. More importantly we prove that, in a Line-of-Sight (LOS) configuration, the discriminating skill of the well-known Zero Forcing precoder is much more sensitive to the antenna array structure and the user location than the Conjugate Beamforming precoder, also known as Time-Reversal. A precoder based on the knowledge of the angular position of all users is then introduced and compared to the other precoders based on channel response knowledge. Its robustness against angle estimation error is illustrated for a specific scenario and serves to back up the importance such a solution represents for future dense 5G networks, angular information being easier to estimate, and more so to keep track of.After that, we show how the knowledge of Directions of Arrival can be used to increase the sum capacity of a multi-user transmission through leakage based power allocation. This allocation uses an estimation of inter-user interference, referred to as Leakage, and we show through simulations how this factor, even under its most simplified form, improves realistic transmissions. Moreover this solution is not iterative and is extremely easy to implement which makes it particularly well suited for high deployment scenarios.Finally we introduce the Hybrid Analog and Digital Beamforming systems that have recently emerged to retain a high number of antennas without as many Radio Frequency (RF) chains, in order to keep high beamforming gains while lowering the complexity of conceiving many antenna base stations. We first describe a user equipment solution allowing the system to form a beam that adapts to its own movement so that it always focuses its energy toward the base station, using an on-board analog array and an Inertial Measurement Unit. Then we compare the performance of a known Hybrid solution with a fully digital Massive MIMO system, having as many RF chains as the Hybrid system, but serving user equipments with beamforming abilities. Mostly we emphasize how such a system allows for great flexibility and evolution, both traits being invaluable features in many future networks.

In this dissertation, the operation of dual-linear polarized antennas is considered in order to provide ideal performance suited for several applications including polarimetric synthetic aperture radar (SAR), wireless and satellite communications. The underlying objectives realized in this work are reported as design realizations of dual-linear polarized antennas with low cross polarization patterns and high isolation between ports that employ special properties of the electromagnetic metamaterial (MTM) structures. Some of these key properties appear as negative permittivity, negative permeability, negative refractive index, and antiparallel nature of the phase velocity and the group velocity. The antenna design is carried out at two frequencies, 5.5 GHz and 10 GHz, and key physical issues that affect the operation of dual-linear polarization operation antennas are treated in light of electromagnetic MTM properties. It’s well known that a dual linear polarized antenna poses a big challenges such as cross polarization patterns and high mutual coupling between two input ports. Therefore, these drawbacks are key topic that receive significant attention in literature which reports on how to mitigate these drawbacks, however, at the expense of complexity of the antenna structures. The MTM structures have received considerable coverage in antenna research for obtaining size reduction, directivity enhancement, and beam steering. For this purpose, different MTMs structures are chosen in this thesis for achieving additional improvements, while keeping the antenna design as simple as possible, something which is very difficult to accomplish using conventional design methods. / In der folgenden Dissertation wird der Einsatz von zweifach linear polarisierten Antennen zur idealen Ausführung von verschiedenen Anwendungen, einschließlich von polarimetrischen Synthetic Aperture Radar (SAR), kabellose und satellitengestützte Kommunikation, diskutiert. Die Ziele dieser Arbeit werden dargestellt durch die Gestaltung von zweifach linear polarisierten Antennen mit gering Kreuz-Polarisationsmustern und die starke Isolation zwischen den Ports durch die einzigartigen Eigenschaften der Strukturen des elektromagnetischen Metamaterials (electromagnetic metamaterial; MTM). Einige dieser Eigenschaften treten als negative Permittivität, negative Permeabilität, negativer Brechungsindex und als antiparallel Richtungen (Gegenvektor) der Phasen-und Gruppengeschwindigkeit auf. Somit wird die Antennengestaltung auf zwei Frequenzen übertragen, 5,5GHz und 10 GHz, und die Ausführung der zweifach linearen Polarisation wird durch die elektromagnetischen Eigenschaften des MTM illustriert. Weil die Kreuzpolarisationsmuster und starke gegenseitige Koppelung zwischen zwei Input-Ports bei einer zweifach linear polarisierten Antenne große Schwierigkeiten bereiten, werden diese im Großteil der Fachliteratur als Schwerpunkte gesetzt, was zu einer Milderung der Nachteile führte, jedoch dafür die Komplexität der Antennenstruktur zunahm. Die Vielfalt an MTM ist ein bedeutender Teil im Bereich der Antennenforschung einschließlich der Größenverkleinerung, der Verbesserung der Richtcharakteristik und der Strahlensteuerung. Für diesen Zweck werden in dieser Dissertation verschiedenste MTM Strukturen ausgewählt um weitere Verbesserungen der Antennenstruktur zu ermöglichen und gleichzeitig die Einfachheit der Struktur zu bewahren, was mit konventionellen Gestaltungsmethoden nur schwer zu erreichen ist.

The Master’s Thesis deals with the design of slot antenna array based on the substrate integrated waveguide (SIW). Various supply methods are described and the design procedure is approached. The antenna array was designed for Wi-Fi band of 5 GHz in the Ansoft HFSS simulation software. The optimalized parameters are impedance bandwidth (low reflection coefficient at antenna input in the desired frequency band) and the gain (the maximum value). As the result of the work 3 antenna arrays based on the substrate integrated waveguide are designed and fabricated: antenna arrays 2x1, 2x2 and antenna array 2x2 supplemented with housing for outdoor use. The work also contains a comparison of simulated and measured parameters of antennas.

The Master’s thesis deals with the design of the dielectric resonator antenna array based on the substrate integrated waveguide. The work describes various feed methods of the dielectric resonator antenna and the technique of the design of the antenna. The antenna array was designed in the simulative program ANSYS HFSS at the frequency 10 GHz, subsequently fabricated and measured. The antenna array has the bandwidth of 570 MHz for S11 better than –10 dB and the gain of 12.1 dBi.

No description available.

Devices that transmit and receive electromagnetic signals are today central to the way people communicate and acquire information from the surroundings. WiDAR, Wideband Digital Array Receiver, is the name of a new system of digital antenna array receivers, which has recently been developed at Saab in Järfälla and is the focus of this thesis. Digital antenna arrays have the benefit over conventional antennas of having their lobes steered electrically, allowing for beamforming, both in reception and transmission. The goal of the thesis has been to characterise certain signal technologies operating in the spectrum of WiDAR, and during the process learn about the limitations of digital antenna array receivers and the system. After studying the system and telecommunication technologies present in the wideband, several measurements were conducted using WiDAR in the field to gather raw data for processing in Matlab. With WiDAR having numerous channels, as well as high sampling rate, large amounts of data was received, leading to difficulties in the processing thereafter. Concluding that three types of signal technologies are certain to be found in WiDAR's spectrum, UMTS/3G, LTE/4G, and DVB-T, their respective narrowbands were studied further through the production of spectrograms of the signal data. Within each band, probability distributions were fit to the histograms of the data. Each of the signal technologies were then characterised by their respective fit to the probability distributions. This resulted in a way of identifying unknown signals from new measurement data from WiDAR. While this method could prove useful as a first step in characterisation, weaknesses such as its lack of depth in the narrowbands are discussed. For further work and the future of the system, it is suggested to e.g. explore the concepts of the multipath problem, or TDM/TDMA in the data. Ultimately, the characterisation of the found signal technologies was moderately successful, however with a sizeable list of limitations and area of improvements.