Dissertations / Theses on the topic 'Array of antennas'
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1
Leonard, Cathy Wood. "Optical feeds for phased array antennas." Thesis, Virginia Polytechnic Institute and State University, 1988. http://hdl.handle.net/10919/80079.
Abstract:
This thesis investigates optical feed methods for phased array antennas. The technical and practical limitations are analyzed and an optimum design is determined. This optimum optical feed is a two-beam interferometric approach which uses acoustooptic phase control. The theory is derived; a computer model is developed; and the limitations are determined. Design modifications are suggested which reduce limitations and greatly extend the range of applications.Master of Science
2
Ong, Chin Siang. "Digital phased array architectures for radar and communications based on off-the-shelf wireless technologies." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2004. http://library.nps.navy.mil/uhtbin/hyperion/04Dec%5FOng.pdf.
Abstract:
Thesis (M.S. in Electrical Engineering)--Naval Postgraduate School, December 2004.Thesis advisor(s): David C. Jenn, Siew Yam Yeo. Includes bibliographical references (p. 63-64). Also available online.
3
Alsawaha, Hamad Waled. "Synthesis of Ultra-Wideband Array Antennas." Diss., Virginia Tech, 2014. http://hdl.handle.net/10919/54553.
Abstract:
Acquisition of ultra-wideband signals by means of array antennas requires essentially frequency-independent radiation characteristics over the entire bandwidth of the signal in order to avoid distortions. Factors contributing to bandwidth limitation of arrays include array factor, radiation characteristics of the array element, and inter-element mutual coupling. Strictly speaking, distortion-free transmission or reception of ultra-wideband signals can be maintained if the magnitude of the radiated field of the array remains constant while its phase varies linearly with frequency over the bandwidth of interest. The existing wideband-array synthesis methods do not account for all factors affecting the array bandwidth and are often limited to considering the array factor and not the total field of the array in the synthesis process.
The goal of this study is to present an ultra-wideband array synthesis technique taking into account all frequency-dependent properties, including array total pattern, phase of the total radiated field, element field, element input impedance, and inter-element mutual coupling. The proposed array synthesis technique is based on the utilization of frequency-adaptive element excitations in conjunction with expressing the total radiated field of the array as a complex Fourier series. Using the proposed method, element excitation currents required for achieving a desired radiation pattern, while compensating for frequency variations of the element radiation characteristics and the inter-element mutual coupling, are calculated.
An important consideration in the proposed ultra-wideband array design is that the "phase bandwidth", defined as the frequency range over which the phase of the total radiated field of the array varies linearly with frequency, is taken into account as a design requirement in the synthesis process. Design examples of linear arrays with desired radiation patterns that are expected to remain unchanged over the bandwidth of interest are presented and simulated. Two example arrays, one with a wire dipole as its element and another using an elliptically-shaped disc dipole as the element are studied. Simulation results for far-field patterns, magnitude and phase characteristics, and other performance criteria such as side-lobe level and scanning range are presented.
Synthesis of two-dimensional planar arrays is carried out by employing the formulations developed for linear arrays but generalized to accommodate the geometry of planar rectangular arrays. As example designs, planar arrays with wire dipoles and elliptical-shaped disc dipoles are studied. The simulation results indicate that synthesis of ultra-wideband arrays can be accomplished successfully using the technique presented in this work. The proposed technique is robust and comprehensive, nonetheless it is understood that the achieved performance of a synthesized array and how closely the desired performance is met also depends on some of the choices the array designer makes and other constraints, such as number of elements, type of element, size, and ultimately cost.Ph. D.
4
Eng, Cher Shin. "Digital antenna architectures using commercial off-the-shelf hardware." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2003. http://library.nps.navy.mil/uhtbin/hyperion-image/03Dec%5FEng.pdf.
Abstract:
Thesis (M.S. in Engineering Science (Electrical Engineering)--Naval Postgraduate School, December 2003.Thesis advisor(s): David C. Jenn, Roberto Cristi. Includes bibliographical references (p. 75-76). Also available online.
5
Scattone, Francesco. "Phased array antenna with significant reduction of active controls." Thesis, Rennes 1, 2015. http://www.theses.fr/2015REN1S168/document.
Abstract:
L'objectif de cette thèse est d'exploiter les phénomènes des ondes de fuite pour améliorer les performances des antennes classiques à ouverture pour les applications spatiales. Ici, nous considérons des configurations planaires où les ondes de fuite sont excitées entre un plan de masse et un superstrat partiellement réfléchissant. Des réseaux de petites ouvertures sur le plan de masse sont utilisés pour alimenter les antennes considérées. Les structures avec superstrat sont développées en configuration réseaux simples ou réseaux à commande de phase, considérées intéressantes en termes de flexibilité du système pour des liens satellitaires de nouvelle génération.Pour étudier efficacement ces antennes, nous avons développé un outil d'analyse basé sur une approche spectrale avec fonction de Green. Cet outil permet d'analyser les structures proposées en prenant en compte l'impact du couplage mutuel entre les éléments sur les performances de rayonnement avec une réduction du temps de calcul et d'utilisation de mémoire.L'augmentation du gain des structures à ondes de fuite peut ouvrir la voie à la réduction du nombre d'éléments des réseaux associés, et donc des commandes en amplitude et phase. Dans une configuration à ondes de fuite, chaque élément du réseau rayonne avec une ouverture équivalente plus grande, augmentant ainsi l'espacement entre les éléments sans affecter le gain global de la structure. Comme largement expliqué dans le manuscrit, les solutions à ondes de fuite représentent par conséquent un avantage majeur pour les antennes du segment utilisateur.En plus de l'amélioration du gain, la technologie à ondes de fuite peut être efficacement exploitée pour synthétiser le diagramme de rayonnement, en choisissant correctement les paramètres de conception de l'antenne. Cette caractéristique peut être utilisée dans les réseaux à commande de phase, pour produire un diagramme d'élément qui minimise les pertes par dépointage et qui filtre les lobes de réseaux. Une procédure de synthèse pour des antennes réseaux raréfiés à ondes de fuite est ainsi présentée dans le manuscrit, ainsi qu'une nouvelle configuration de réseaux avec superstrat irrégulier. Ce dernier permet de réduire les lobes secondaires de l'antenne en utilisant une excitation uniforme. Cette dernière configuration montre clairement que la capacité de modifier le diagramme de rayonnement est la caractéristique la plus attrayante des antennes planaires à ondes de fuite, pour être utilisée dans des solutions de réseaux à commande de phaseThe objective of this thesis is to exploit the leaky-wave phenomena to enhance the performance of classical aperture antennas for space applications. Here, we consider planar configurations where the leaky modes are excited between a ground plane and a partially reflective superstrate. Arrangements of small apertures opening on the ground plane are used to feed the antennas under study. The superstrate-like leaky-wave structures are developed in array or phased array configurations, considered of interest in terms of flexibility of the system for next generation satellite links. In order to efficiently study planar leaky-wave arrays, we have developed an analysis tool based on a Green's function spectral approach. The developed tool allows to precisely analyze the proposed structure by taking into account the impact of the mutual coupling among the elements on the radiation performance of the whole antenna. In addition, it can handle extremely large structures in terms of wavelengths with a small computational effort with respect to commercial tools. In particular, the gain enhancement of leaky-based structures can pave the way to the reduction of the number of elements of the associated phased arrays. In a leaky-wave configuration each element of the array will radiate with a larger equivalent aperture allowing a larger spacing among elements without affecting the final gain of the whole structure. This aspect is particularly important in the case of phased arrays, where phase shifters and control cells are, typically, the most expensive components of the system. As extensively explained in the manuscript, antennas for user segment might find the highest benefit by using leaky-wave solutions. Besides the gain enhancement, the leaky-wave technology can be effectively exploited to conveniently shape the radiation pattern by properly engineering the design parameters of the antenna. This capability can be used in phased arrays to generate a convenient element pattern to minimize the scan losses and filter the grating lobes appearing in the visible space when dealing with periodicities larger than a wavelength. Therefore, a synthesis procedure for thinned leaky-wave arrays is presented in the manuscript. Also, a novel array configuration, the irregular superstrate array, is presented. The irregular superstrate allows the reduction of the side lobes of the antenna below -20 dB in the considered 2.5 % band, using a uniform excitation. This last configuration clearly shows that the shaping capability of leaky-wave antennas is the most appealing feature to be used in phased array solutions
6
Sundaram, Ananth Ramadoss Ramesh. "Electronically Steerable Antenna Array using PCB-based MEMS Phase Shifters." Auburn, Ala., 2006. http://repo.lib.auburn.edu/2006%20Summer/Theses/SUNDARAM_ANANTH_51.pdf.
7
Bertulli, Scott. "MATLAB-Based Dipole Array Simulator Tool For MIT Haystack Observatory." Link to electronic thesis, 2005. http://www.wpi.edu/Pubs/ETD/Available/etd-050505-104840/.
8
Li, Pei. "Novel wideband dual-frequency L-probe fed patch antenna and array /." access abstract and table of contents access full-text, 2006. http://libweb.cityu.edu.hk/cgi-bin/ezdb/thesis.pl?phd-ee-b21471447a.pdf.
Abstract:
Thesis (Ph.D.)--City University of Hong Kong, 2006."Submitted to Department of Electronic Engineering in partial fulfillment of the requirements for the degree of Doctor of Philosophy" Includes bibliographical references (leaves 179-189)
9
Hee, Ta Wei. "Wide bandwidth conformal array antennas." Thesis, University of Birmingham, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.521971.
10
Davids, Vernon Pete. "Implementation of a wideband microstrip phased array antenna for X-band radar applications." Thesis, Cape Peninsula University of Technology, 2009. http://hdl.handle.net/20.500.11838/1100.
Abstract:
Thesis (MTech (Electrical Engineering))--Cape Peninsula University of Technology, 2009This thesis presents the design, analysis and implementation of an eight-element phased array antenna for wideband X-band applications. The microstrip phased array antenna is designed using eight quasi-Yagi antennas in a linear configuration and is printed on RT/Duroid 6010LM substrate made by Rogers Corporation. The feeding network entails a uniform beamforming network as well as a non-uniform -25 dB Dolph-Tschebyscheff beamforming network, each with and without 45° delay lines, generating a squinted beam 14° from boresight. Antenna parameters such as gain, radiation patterns and impedance bandwidth (BW) are investigated in the single element as well as the array environment. Mutual coupling between the elements in the array is also predicted. The quasi-Yagi radiator employed as radiating element in the array measured an exceptional impedance bandwidth (BW) of 50% for a S11 < -10 dB from 6 GHz to 14 GHz, with 3 dB to 5 dB of absolute gain in the frequency range from 8 GHz to 11.5 GHz. The uniform broadside array measured an impedance BW of 20% over the frequency band and a gain between 9 dB to 11 dB, whereas the non-uniform broadside array measured a gain of 9 dB to 11 dB and an impedance BW of 14.5%. Radiation patterns are stable across the X-band. Beam scanning is illustrated in the E-plane for the uniform array as well as for the non-uniform array.
11
Aqbi, Sadiq. "Improving the Performance of Dual Linear Polarization Antennas with Metamaterial Structures." Doctoral thesis, Universitätsbibliothek Chemnitz, 2018. http://nbn-resolving.de/urn:nbn:de:bsz:ch1-qucosa-233539.
Abstract:
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 methodsIn 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
12
Ng, Kwong-Tai. "Admittance properties of a slot array with parasitic wire arrays in a stratified medium /." The Ohio State University, 1985. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487259580262744.
13
Uhl, Brecken. "Direct Spatial Antenna Modulation for Phased-Array Applications." International Foundation for Telemetering, 2009. http://hdl.handle.net/10150/606129.
Abstract:
ITC/USA 2009 Conference Proceedings / The Forty-Fifth Annual International Telemetering Conference and Technical Exhibition / October 26-29, 2009 / Riviera Hotel & Convention Center, Las Vegas, NevadaNew technologies are sought to meet the requirements of evolving telemetry capabilities such as new operating bands, increased test article and ground segment collaboration, and on-the-fly quality of service (QOS) management. Smart antennas may contribute to this evolution by directing signal energy where and when it is needed. Direct spatial antenna modulation (DSAM) represents a new approach to cost-effective smart antennas potentially offering benefits such as post-amplifier modulation, polarization reconfigurability, phase-shifterless phased arrays, oscillator-less frequency conversion, and pre-receiver processing gain. The basic DSAM approach has recently been proven through analysis, simulation, and prototyping, with significant implications for future capabilities.
14
Dorsey, William Mark. "Low Profile, Printed Circuit, Dual-Band, Dual-Polarized Antenna Elements and Arrays." Diss., Virginia Tech, 2009. http://hdl.handle.net/10919/26683.
Abstract:
Dual-band antenna elements that support dual-polarization provide ideal performance for applications including space-based platforms, multifunction radar, wireless communications, and personal electronic devices. In many communications and radar applications, a dual-band, dual-polarization antenna array becomes a requirement in order to produce an electronically steerable, directional beam capable of supporting multiple functions. The multiple polarizations and frequency bands allow the array to generate multiple simultaneous beams to support true multifunction radar. Many of the applications in spaced-based systems and personal electronic devices have strict restraints on the size and weight of the antenna element, favoring a low-profile, lightweight device.
The research performed in this dissertation focuses on the design of a dual-band, dual-polarized antenna element capable of operating as an isolated element or in an array environment. The element contains two concentric, dual-polarized radiators. The low band radiator is a shorted square ring antenna, and the high band radiator is a square ring slot. Each constituent element achieves circular polarization through the introduction of triangular perturbations into opposing corners of the radiating element. This technique has been shown to introduce two, near-degenerate modes in the structure that – when excited in phase quadrature – combine to form circular polarization. The perturbations allow circular polarized operation with only a single feed point. The sense of the circular polarization is determined by the location of the feed point with respect to the perturbations. Both senses of circular polarization are excited by the introduction of orthogonal feeds for each of the two radiating elements. Thus, dual-ban, dual-circular polarization is obtained.
The element achieves a low-profile from its printed circuit board realization. The high band square ring slot is realized in stripline. The orthogonal feeding transmission lines are printed on opposing sides of an electrically thin dielectric layer to allow them to cross without physically intersecting. This thin feeding substrate is sandwiched between two dielectric layers of matched dielectric constant. A ground plane is located on the top and bottom of the sandwiched dielectric structure, and the top ground plane contains the square ring slot with perturbed corners. Slotted stripline structures have been shown in the literature to excite a parallel-plate mode that can degrade overall performance of the antenna. Plated through holes are introduced at the outer perimeter of the square ring slot to short out this parallel-plate mode. The plated through holes (also called vias) serve as the shorting mechanism for the low band microstrip shorted square ring radiator. This element also contains triangular perturbations at opposing corners to excite circular polarization with a single feed point. In this element, orthogonal probe feeds are present to excite both senses of circular polarization.
A dual-band, dual-polarized antenna element was built, tested, and compared to simulations. The constructed element operated at two distinct industrial, scientific, and medical (ISM) frequency bands due to their popularity in low power communications. The antenna element was realized in a multilayer printed circuit layout. A complex design procedure was developed and submitted to a printed circuit board company who manufactured the antenna element. The s-parameters of the antenna were measured using a Network Analyzer, and the results show good agreement with simulations. The radiation and polarization characteristics were measured in a compact range facility. These results also agreed well with simulations. The measured results verify the simulation models that were used in the simulations and establish a confidence level in the feasibility of constructing this element. The dual-band, dual-polarization nature of this element was established through the construction and measurement of this element.
A novel size reduction technique was developed that allows for significant reduction of the element's footprint. This size reduction facilitates the placement of this element within an array environment. The loading technique utilizes a structure analogous to a parallel-plate capacitor to drastically reduce the overall size of the low frequency shorted square ring. The loading structure uses a substrate that is separate from that of the radiating elements. This allows the load to use a high dielectric material to achieve a high capacitance without requiring the radiating elements to be printed on high dielectric material that is potentially expensive and lossy at microwave frequencies.
The two frequency bands were selected to be in separate industrial, scientific, and medical (ISM) bands. These frequency bands are increasingly popular in low power communication devices because unlicensed operation is permitted. The 2.45 GHz and 5.8 GHz ISM bands are commonly used for applications including Bluetooth technology, multiple 801.11 protocol, cellular phone technology, and cordless phones. The ISM bands were chosen for this antenna element due to their popularity, but this antenna is not restricted to these bands. The frequency ratio can be altered by controlling the dielectric constant used in the printed circuit board design, the parameters of the capacitive loading structure, and the size of the constituent elements that are used.
After the size reduction technique is applied, the dual-band, dual-polarized elements can be placed in an array environment resulting in an array capable of generating both senses of circular polarization in the two, distinct ISM bands. This provides an aperture capable of supporting multiple functions. Depending on the applications required, the frequency bands of the antenna element can be altered to suit the particular system needs.
The array analysis performed in this dissertation used a unique hybrid calculation technique that utilizes nine active element patterns to represent the patterns of the individual elements within a large antenna array. A common first look at array performance is achieved by multiplying the element pattern of an isolated element by an array factor containing the contributions of the geometrical arrangement of the antenna elements. This technique neglects mutual coupling between elements in the array that can alter the impedance match and radiation characteristics of the elements in the array. The active element pattern defines the radiation pattern of a given element in an array when all other elements are terminated in a matched impedance load. The active element pattern is unique for each element in an array. When these patterns are summed, the exact array pattern is obtained. While this technique has the advantage of accuracy, it is not ideal because it requires the simulation, calculation, or measurement of the pattern for each element in the array environment. The technique developed in this dissertation uses only nine active element patterns. These elements are then assigned to represent the active element patterns for all elements in the array depending on the geometrical region where the given element resides. This technique provides a compromise between the speed of using a single element pattern and the accuracy of using the unique active element pattern for each element in the array.
The application of these two concentric, coplanar radiators along with the capacitive loading technique provides a unique contribution to the field of antenna engineering. The majority of dual-band antenna elements in the literature operate with a single polarization in each band. The ones that operate with dual-polarization in each band are typically limited to dual-linear polarization. Circular polarization is preferable to linear in many applications because it allows flexible orientation between the transmitting antenna and receiving antenna in a communications system, while also mitigating multipath effects that lead to signal fading. The ability to operate with two, orthogonal senses of circular polarization allows a system to reuse frequencies and double system capacity without requiring additional bandwidth. The uniqueness of this element lies in its ability to provide dual-circular polarization in two separate frequency bands for an individual element or an antenna array environment. The arrangement of the two element geometries with the addition of the novel capacitive loading technique is also unique. The performance of this element is achieved while maintaining the light weight, low profile design that is critical for many wireless communications applications.
This dissertation provides a detailed description of the operation of this dual-band, dual-polarized antenna element. The design of the constituent elements is discussed for several polarization configurations to establish an understanding of the building blocks for this element. The dual-band, dual-polarized element is presented in detail to show the impedance match, isolation, and axial ratio performance. The capacitive loading technique is applied to the dual-band, dual-polarized element, and the performance with the loading in place is compared to the performance of the unloaded element. Next, there is an in-depth description of the array calculation technique that was developed to incorporate mutual coupling effects into the array calculations. This technique is then applied to the dual-band, dual-polarized array to show the performance of several array sizes.Ph. D.
15
Da, Silveira Marthinus Willem. "Analysis of spatially distributed adaptive antenna array systems in cellular networks." Pretoria : [s.n.], 2005. http://upetd.up.ac.za/thesis/available/etd-06032005-090336/.
16
Persson, Patrik. "Analysis and Design of Conformal Array Antennas." Doctoral thesis, KTH, Teoretisk elektroteknik, 2002. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-3290.
Abstract:
Today there is a great need for communication between people and even between things, using systems onboard e.g. aircraft, cars, ships and satellites. As a consequence, these communications needs require antennas mounted on or integrated in the surfaces of different vehicles or platforms, i.e. conformal antennas. In order to ensure proper operation of the communication systems it is important to be able to determine the characteristics of these antennas. This thesis is about the analysis and design of conformal antennas using high frequency asymptotic methods. Commonly used eigenfunction solutions or numerical methods such as FDTD, FEM or MoM are difficult to use for arbitrarily shaped electrically large surfaces. However, the high frequency approximation approach together with an accurate ray tracing procedure offers a convenient solution for these surfaces. The geodesics (ray paths) on the surfaces are key parameters in the analysis and they are discussed in detail. In the first part of the thesis singly and doubly curved perfectly electrical conducting (PEC) surfaces are studied, with respect to the mutual coupling among aperture type elements. A synthesis problem is also considered where the effect of the mutual coupling is taken into account. As expected, the mutual coupling must be included in the synthesis procedure to be able to realize the prescribed pattern, especially in the shaped main lobe. Furthermore, the polarization of the antenna elements is very important when considering antennas on generally shaped surfaces. For such antennas the polarization must most likely be controlled in some way for a proper function. For verification of the results two experimental antennas were built at Ericsson Microwave Systems AB, Mölndal, Sweden. The first antenna is a circular cylinder with an array of rectangular waveguide fed apertures and the second antenna is a doubly curved surface (paraboloid) with circular waveguide fed apertures. It is found that it is possible to obtain very accurate results with the asymptotic method when it is combined with the Method of Moments, i.e. a hybrid method is used. The agreement compared to measurements is good at levels as low as –80 dB in many cases. The second part of the thesis is about the development of a high frequency approximation for surface field calculations on a dielectric covered PEC circular cylinder. When using conformal antennas in practice they have to be covered with a radome for protection and with the method developed here this cover can be included in the analysis. The method is a combination of two different solutions, one valid in the non-paraxial region of the cylinder and the other is valid in the paraxial region. The method is verified against measurements and reference results obtained from a spectral domain moment method code.QC 20100616
17
Römer, Christian. "Slotted waveguide structures in phased array antennas /." Karlsruhe : IHE, 2008. http://bvbr.bib-bvb.de:8991/F?func=service&doc_library=BVB01&doc_number=016491138&line_number=0001&func_code=DB_RECORDS&service_type=MEDIA.
18
Darwood, Peter B. "Pattern synthesis for small phased array antennas." Thesis, University of Bristol, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.262843.
19
MOREIRA, FERNANDO JOSE DA SILVA. "FEED ARRAY REFLECTOR ANTENNAS FOR SHAPED BEAMS." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 1992. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=8839@1.
Abstract:
Este estudo tem como tema a análise dos campos radiados
por um conjunto de alimentadores para a iluminação de um
sistema único refletor embarcado em satélite, utilizando
para a produção de diagramas modelados. É usada uma
técnica para o tratamento do acoplamento mútuo entre os
campos de aberturas retangulares num plano condutor
elétrico infinito, de forma que os alimentadores aqui
tratados serão guias retangulares abertos e cornetas
piramidais. Uma formulação assintótica inédita foi
desenvolvida para o aclopamento entre duas aberturas
afastadas entre si. Como aplicação foram realizadas
diversas sínteses para a iluminação do território
brasileiro.This study aims the analysis of the radiated fields of na array feeding a single reflector system for satellite applications, used to produce shaped beams. It is used a technique for the treatment of the mutual coupling effects between rectangular apertures in an infinite electric conductor plane, so the feeds used are open-ended rectangular waveguides and pyramidal horns. It is also presented a new asymptotic approach for the mutual coupling between far-distanced apertures. In order to study the application of these formulations, some synthesis for the illumination of the Brazilian territory were made.
20
Marantis, L. "Spherical array antennas for LEO satellite communications." Thesis, University College London (University of London), 2014. http://discovery.ucl.ac.uk/1449259/.
Abstract:
The trend in the construction of the latest array antennas is such, that electronic beam scanning can be conducted for a significantly large angular sector. Indeed, as far as circular array antennas are concerned, the quality of the radiation pattern will not be impaired when scanned in the full azimuthal axis. Compared to planar and several different shapes of conformal antenna arrays, spherical array antennas have the unique property of scanning their beam with no deterioration in full spherical coverage (i.e. azimuth and elevation axes). Furthermore, multi-beam functioning and direction finding techniques can be applied to spherical array antennas. In contrast to antennas that use mechanical motors for steering, they exhibit higher speed and stability. Low Earth Orbit (LEO) satellite communications can utilize the aforementioned properties of spherical array antennas. Spherical harmonic (phase mode) theory constitutes the base on which the signal processing of the spherical array antenna is developed. In this analysis, spherical harmonics are employed, which take advantage of the sphere’s symmetry and regenerate themselves in the far-field. The spherical phase mode approach is able to provide considerable improvements and computational simplification in several array processing levels. Specifically, research efforts are concentrated toward the choice of an optimal uniform spherical distribution and the minimum number of array elements that are necessary in the process. Various antenna element distributions are investigated and compared to each other placing special emphasis on the design and fabrication efficiency. Additionally, the direction finding potential of a spherical array antenna is explored by applying one of the main DOA estimation algorithms used with spherical arrays, the spherical ESPRIT algorithm. A spherical array, called LISA, has been designed and a prototype demonstrator has been manufactured. The spherical array has a radius of 40 cm, and operates at 3 GHz, employing circular polarization. A multi-planar approach, with 240 triangular planar tiles approximating the spherical surface, is adopted. Special attention is given to the RF front end of the array, and especially to the development of the microstrip antenna design that is accommodated on each tile (three elements) and a bespoke feed network. Valuable simulation and measurement results are also provided, demonstrating satisfactory performance of the tested tiles and offering essential conclusions for discussion and further investigation.
21
Zhang, Piyou. "Slotted Spiral Antennas and Widebandwidth Array Systems." University of Cincinnati / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1222311888.
22
De, Witte E. "Design and development of spherical array antennas." Thesis, University College London (University of London), 2007. http://discovery.ucl.ac.uk/1446227/.
Abstract:
Array antennas have been developed that can achieve electronic beamsteering over wide angles. With circular array antennas, a radiation pattern can be steered over 360 azimuthal degrees without pattern deterioration. Some applications may require an omnidirectional beamsteering capability in azimuth as well as in elevation, with antenna characteristics that are independent from the direction of the beam. To achieve this without mechanical actuators requires an antenna that is homeomorphic to the sphere. Spherical array antennas are the 3-dimensional equivalent of circular array antennas and offer a full omnidirectional beamsteering coverage. Using standard Fourier techniques, the analysis and synthesis of a circular array can be simplified. The technique is known as phase mode theory and allows a number of signal process ing techniques such as electronic direction finding to be demonstrated. The symmetry found in spherical array antennas can equally be exploited using spherical harmonics as a basis for Fourier analysis. Spherical array antennas have not enjoyed the same attention as circular arrays, nor have they been the subject, with the exception of SONAR arrays, of a profound study that is equivalent to phase mode theory. This thesis aims to put spherical arrays on the same foot as circular arrays, by using spherical modes to build the theoretical framework for the analysis, synthesis and design of spherical array antennas. Using a technique for conformal array antennas, an holistic model for the spherical array antenna is derived to analyse the radiation from complex spherical arrays, based on analytically obtained expressions. Mutual coupling effects are quantified and included in the calculations. Also some typical antenna characteristics and design considerations are reviewed in the light of modal theory, in order to obtain design formula's for the spherical array antenna. Apart from the electromagnetic approach, attention is given to the processing of the signals. Modal theory lends itself for the development of smart antennas, and the foundations to do that with spherical arrays are laid down. A particular problem arises when one wants to distribute the array elements evenly over the spherical surface. This topic is also given an in-depth treatment, for distributions of single elements as well as for more advanced subarraying techniques. To back up the findings from theory and simulation, as well as to demonstrate the unique capabilities of the spherical array antenna, a prototype array has been designed and partially constructed. The design and development of this antenna is covered to the point where a partially completed spherical array could be measured. Results of these measurements are encouraging and sufficient to show the potential of spherical array antennas. Finally, suggestions are given for future experiments and how to further advance spherical array technology.
23
Middlebrook, Christopher. "INFRARED ANTENNA-COUPLED PHASED-ARRAY." Doctoral diss., University of Central Florida, 2007. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/3266.
Abstract:
Phased-array antennas are commonplace in the radiofrequency portion of the electromagnetic spectrum. Exploitation of phasing effects between multiple antennas facilitates a wide range of applications, including synthetic-aperture radar, beam forming, and beam scanning. For the first time, the phased addition of multiple dipole antennas is demonstrated in the infrared, at a wavelength of 10.6 micrometers. Coplanar strip lines are used to interconnect the antennas, preserving the phase of the individual contributions. Several different proof-of-concept experiments are performed, using planar antennas fabricated with direct-write electron-beam lithography. Infrared-frequency currents from two dipole antennas are summed together at a common feedpoint and dissipated in a bolometric load. Angular pattern measurements show that the direction of maximum gain depends on the phase difference between the antennas. As more antennas are added together in phase, beam narrowing is observed in the angular response. Another experiment uses a two-dipole array to directly measure the magnitude of the mutual coherence function, at the plane of the antennas, of a spatially incoherent narrowband source. Measurements are also made of the broadside antenna response comparing air-side and substrate-side situations for a dipole antenna fabricated on a hemispherical immersion lens. In all cases, the measured behavior is confirmed by electromagnetic analysis.Ph.D.
Optics and Photonics
Optics and Photonics
Optics PhD
24
Najafabadi, Reza M. "Analysis and design of cylindrically conformable microwave phased array antennas for hyperthermia applications." Diss., Georgia Institute of Technology, 1995. http://hdl.handle.net/1853/16473.
25
Ong, Chee Hwee. "Modeling of the ring-hybrid dipole antenna and mutual coupling in a small antenna array." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2003. http://library.nps.navy.mil/uhtbin/hyperion-image/03Dec%5FOng.pdf.
Abstract:
Thesis (M.S. in Engineering Science)--Naval Postgraduate School, December 2003.Thesis advisor(s): David C. Jenn, Roberto Cristi. Includes bibliographical references (p. 95). Also available online.
26
Lin, Chih-heng. "Distributed subarray antennas for multifunction phased-array radar." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2003. http://library.nps.navy.mil/uhtbin/hyperion-image/03sep%5FLin.pdf.
Abstract:
Thesis (M.S. in Systems Engineering)--Naval Postgraduate School, September 2003.Thesis advisor(s): David C. Jenn, Richard W. Adler. Includes bibliographical references (p. 71-72). Also available online.
27
Pine, Shannon Robert. "Manufacturing structurally integrated three dimensional phased array antennas." Thesis, Available online, Georgia Institute of Technology, 2006, 2006. http://etd.gatech.edu/theses/available/etd-04062006-115019/.
Abstract:
Thesis (M. S.)--Mechanical Engineering, Georgia Institute of Technology, 2006.Dr. Jonathan Colton, Committee Chair ; Dr. John Muzzy, Committee Member ; Dr. Daniel Baldwin, Committee Member ; Dr. John Schultz, Committee Member.
28
Ellgardt, Anders. "Wide-angle scanning wide-band phased array antennas." Doctoral thesis, KTH, Elektroteknisk teori och konstruktion, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-10225.
Abstract:
This thesis considers problems related to the design and the analysis of wide-angle scanning phased arrays. The goals of the thesis are the design and analysis of antenna elements suitable for wide-angle scanning array antennas, and the study of scan blindness effects and edge effects for this type of antennas. Wide-angle scanning arrays are useful in radar applications, and the designs considered in the thesis are intended for an airborne radar antenna.After a study of the wide-angle scanning limits of three candidate elements, the tapered-slot was chosen for the proposed application.A tapered-slot antenna element was designed by using the infinitive array approach and the resulting element is capable of scanning out to 60° from broadside in all scan planes for a bandwidth of 2.5:1 and an active reflection coefficient less than -10 dB. This design was implemented on an experimental antenna consisting of 256 elements.The predicted performance of the antenna was then verified by measuring the coupling coefficients and the embedded element patterns, and the measurements agreed well with the numerical predictions.Since the radar antenna is intended for applications where stealth is important, an absorbing layer is positioned on top of the ground plane to reduce the radar cross section for the antenna's cross-polarization.This absorbing layer attenuates guided waves that otherwise lead to scan blindness, but does not adversely affect the antenna performance for the desired scan directions and frequencies.The highest frequency limit of the tapered-slot element is set by scan blindnesses. One of these scan blindnesses is found to be unique to tapered-slot elements positioned in triangular grids. This scan blindness is studied in detail and a scan blindness condition is presented and evaluated.The evaluation of the experimental antenna shows that edge effects reduce the H-plane performance of the central elements.These edge effects are further studied and characterized, by comparing the scattering parameters for finite-by-infinite arrays and infinite arrays.In this way it is possible to divide the edge effects into two categories: those caused by finite excitation, and those caused by perturbed currents due to the geometry of the edge. A finite difference time domain code with time shift boundaries is used to compute the active reflection coefficients needed to compute the scattering parameters, but this code cannot directly compute the active reflection coefficient for all the required phase shifts.Hence, an additional method is presented that makes it possible to compute arbitrary phase shifts between the elements using any numerical code with limited scan directions.QC 20100712
29
Li, Wenting. "Design of printed array antennas for wireless communications." Thesis, University of Kent, 2018. https://kar.kent.ac.uk/71528/.
Abstract:
Compared to parabolic reflector antennas, printed array antennas have compact size, light weight and low cost. Many printed array antennas have been reported in the literature, but there are lots of challenges remaining. For example, how to achieve polarization-reconfigurable circularly polarized (CP) array antennas? How to reduce the thickness of folded reflectarray CP antennas? How to increase the bandwidth of reflectarray antennas? How to achieve multi-beam radiation? To tackle these challenges, several novel designs of printed array antennas are proposed in this dissertation. First, a novel design of a polarization-reconfigurable CP antenna is proposed. It is the first time an electronically polarization-reconfigurable CP antenna with a single-substrate polarizer is reported. The antenna consists of a slot antenna and an electronically polarization-reconfigurable polarizer (EPRP), which could convert the linearly polarized (LP) waves from the slot antenna to CP waves. The polarization of the antenna could be electronically switched to left-hand circular polarization (LHCP) or right-hand circular polarization (RHCP) by changing the states of the positive-intrinsic-negative (PIN) diodes that are loaded on the polarizer. There are several features of applying an EPRP in this design. 1) The DC circuit of PIN diodes is completely isolated from the RF signals. 2) The PIN diodes are not mounted on the RF feed network. 3) In this antenna, 32 PIN diodes are mounted on the EPRP. The average current of each PIN diode is quite small. Therefore, the antenna can radiate more power without damaging the diodes. 4) The gain of antennas is improved as the aperture of the slot antenna is enlarged by the EPRP. Then, a novel folded CP reflectarray with a significantly-reduced antenna thickness is designed. The antenna consists of a CP feed antenna, a reflecting surface and a circular polarization selective surface (CPSS). The CPSS is transparent for RHCP waves and reflects LHCP waves. By applying the CPSS as the polarization grid for CP waves, the thickness of the CP reflectarray antenna is reduced significantly. It is the first time that the CPSS is applied as the polarization grid in a folded CP reflectarray antenna. To overcome the problem of narrow bandwidth of reflectarrays, one ultra-wide-band tightly coupled dipole reflectarray (TCDR) antenna is proposed. This is the first report of a reflectarray using the concept of tightly coupled elements, and the reflectarray antenna is shown to achieve much wider working bandwidth compared with all the reflectarray antennas that are reported in the previous literature. The reflectarray consist of a wide-band feed antenna and a wide-band reflecting surface. The proposed antenna combines the features of tightly coupled arrays and those of reflectarrays. As a result, the TCDR antenna has an ultra-wide bandwidth, and a much simpler feed network compared with tightly coupled arrays and other ultra-wide-band direct radiation array. A novel method to mini-mize the phase errors of the wideband reflectarray is also proposed. In its operating frequency band, the TCDR antenna has stable main beams and reasonable side lobe levels (SLL). A new method of improving the polarization purity of the TCDR antenna is also proposed. Based on the method, two reflectarray antennas are designed and simulated. The simulated results show that the proposed method could reduce the cross-polarization of the TCDR antenna significantly. Finally, a novel method of designing a Nolen matrix is proposed, and the derivation of the method is given as well. The method is more concise compared with that reported in the previous literature. Based on this method, a multi-beam antenna fed by a 5×5 Nolen matrix network is proposed. The multi-beam antenna is simulated, fabricated and measured. The simulated and measured results prove the effectiveness of the proposed method of designing a Nolen matrix. In this thesis, in order to accurately evaluate the performance of the proposed antennas, full-wave electromagnetic simulations are carried out by using commercial tools such as High Frequency Structure Simulator and Computer Simulation Technology Microwave Studio. Prototypes of the antenna designs are fabricated and measured. The simulated and measured results agree well.
30
Barros, Sara Pena. "OFDM for data distribution in phased array antennas." Master's thesis, Universidade de Aveiro, 2013. http://hdl.handle.net/10773/12879.
Abstract:
Mestrado em Engenharia Eletrónica e TelecomunicaçõesCurrently, all the control data behind the RF front-end modules in phased array radars is transmitted digitally and simultaneously by means of optical ber, resulting in a massive distribution network. The design of cheaper radars requires alternative ways of transmission to be explored. An intuitive and rather straight approach is to take advantage of the already existent RF layer used for the distribution of the radar pulse. The aim of this thesis work is to investigate OFDM as a modulation option for that approach and to determine whether or not it is a viable one. As proof of concept, experimental results are presented and discussed.
Actualmente, toda a informa cão de controlo por detráas dos móodulos T/R (Transmit/ Receive) em radares com phased arrays e transmitida digital e simultaneamente atrav és de fi bra optica, resultando numa rede de distribuiçaõ massiva. Para que se possa reduzir o custo de produção e limitações no design, e fundamental a exploração de alternativas para a transmissão destes dados. Uma ideia intuitiva e que não implica grandes modi ca ções estruturais, e tirar vantagem da j a existente layer de RF (R adio Frequência) usada para distribuição do pulso de radar pelos m ódulos. O objectivo desta tese é investigar OFDM (Orthogonal Frequency Division Multiplexing) como uma das opções para modulação do novo sinal de RF responsável pela informa ção de controlo e determinar se esta é ou não uma escolha vi ável. Como prova de conceito, resultados experimentais serão apresentados e discutidos.
31
Mahbubani, Shaan Suresh. "Antarctica exploring the capabilities of phased array antennas /." Diss., Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC campuses, 2008. http://wwwlib.umi.com/cr/ucsd/fullcit?p1459288.
Abstract:
Thesis (M.S.)--University of California, San Diego, 2008.Title from first page of PDF file (viewed Nov. 6, 2008). Available via ProQuest Digital Dissertations. Includes bibliographical references (p. 123-125).
32
Lin, Sun James. "On the scan impedance of an array of V-dipoles and the effect of the feedlines /." Connect to resource, 1985. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1209741301.
33
Hock, Chua Eng. "Reduction of mutual coupling in small dipole array antenna." Thesis, Monterey, California. Naval Postgraduate School, 2003. http://hdl.handle.net/10945/1130.
Abstract:
The mutual coupling in phased array is a well-known phenomenon. It affects the active element pattern of the array as the phase of the individual element is altered. In an array that has many elements, the effect is identical for all the elements that are nearer to the center of the antenna, thus allowing a more predictable scan performance with respect to the phase of the elements. However, in a small array that has only three elements, the active element pattern for the elements at the end can be significantly different from the center element and this affects the predictability of operations such as direction finding. The thesis investigates two ways that can potentially reduce or at least control the mutual coupling in small arrays. The first method simply adds a dummy element with a special load condition to each end of the array to make the edge element "feel" as if there are more elements next to it. The second method uses a passive feedback circuit to both monitor and correct the magnitude and phase of the mutual coupling at the input of each array element. A hybrid ring is attached to each of the elements to monitor the amount of interference received by that element. Simulation results for the dummy element method shows that some reduction in phase error can be achieved if the spacing and length of the element are selected properly. The compensation network approach relies on an efficient two-port array element. The research has focused on the design of a two-port printed circuit dipole that could be used in such an array. The dipole was designed, simulated, and fabricated. Future research will use this element in a compensation network.Republic of Singapore Navy author.
34
Chua, Eng Hock. "Reduction of mutual coupling in small dipole array antenna /." Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2003. http://library.nps.navy.mil/uhtbin/hyperion-image/03Mar%5FChua%5FEngHock.pdf.
35
Belentepe, Bilge. "Electromagnetically coupled microstrip patch antenna array design." Thesis, University of Surrey, 1993. http://epubs.surrey.ac.uk/842825/.
Abstract:
This work is an effort to investigate and derive a simple equivalent circuit model to represent an electromagnetically coupled microstrip patch antenna. This provides a simple approach to the complicated electromagnetic coupling behaviour in the patch. A simplified theory based on the broadside coupled line and improved transmission line theories is developed to derive the equivalent circuit of EM coupled patch antenna. The design parameters are determined from the above mentioned theory. Computer programs are developed to provide a practical design of such antennas without involving complicated, time consuming, rigorous methods. A number of sample patches are designed, made and tested to verify the theory. These elements are also incorporated into an array to evaluate their performance in an array environment. The impedance and pattern measurements are made for comparison with theoretical results.
36
Arnott, Robert. "Array processing for digital mobile radio." Thesis, Imperial College London, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.338780.
37
McCann, John Forrest. "On the design of large bandwidth arrays of slot elements with wide scan angle capabilities." Connect to resource, 2006. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1209590321.
38
Parfitt, Andrew J. "Substrate supported metal strip antennas for monolithically fabricated millimetre wavelength arrays /." Title page, table of contents and abstract only, 1992. http://web4.library.adelaide.edu.au/theses/09PH/09php2289.pdf.
39
Huysamen, Johan Herman. "Electrically small planar antenna for circular polarization /." Link to the online version, 2007. http://hdl.handle.net/10019/1047.
40
Irci, Erdinc. "Low-Profile Wideband Antennas Based on Tightly Coupled Dipole and Patch Elements." The Ohio State University, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=osu1316456337.
41
Yeo, Chee Beng. "Effects of mutual coupling in small dipole array antennas." Thesis, Monterey, California. Naval Postgraduate School, 2002. http://hdl.handle.net/10945/5999.
Abstract:
Approved for public release, distribution is unlimitedApproved for public release, distribution is unlimited
In the classical approach of antenna theories, mutual coupling between elements is usually ignored. However, depending on the application, errors due to mutual coupling can be significant. This thesis investigates the effects of mutual coupling between elements in small dipole arrays via software simulations that use the Methods of Moment, a numerical technique that accounts for mutual coupling, as opposed to the classical approach, which does not. The simulations show that the active impedance of any element in an array depends on both the self and mutual impedances and that the terminal current phases, hence directivity, of an array are affected by mutual coupling such that the array pattern deviates from that defined by classical theoretical approach. In an active element pattern approach, the mutual couplings in an array are accounted for through the active element, making this approach a viable one to study the radiation patterns of practical dipole arrays. The examination of a small array provides a useful environment in which to develop, optimize and evaluate the radiating elements, thus providing better understanding of the effects of mutual coupling in antenna arrays and facilitating the design of corresponding compensation techniques in practical arrays.
42
McColl, Iain. "Radiating and coupling elements in waveguide planar array antennas." Thesis, Heriot-Watt University, 1992. http://hdl.handle.net/10399/788.
43
Uchendu, Iyemeh E. "Passive amplitude and hybrid parasitic beam steerable array antennas." Thesis, University of Surrey, 2018. http://epubs.surrey.ac.uk/845688/.
Abstract:
Highly directive antennas with beam steering capabilities are needed to overcome high path-loss, mitigate against interference from unwanted signals and to ensure network connectivity for the next generation 5G millimetre wave communication systems. Phased arrays using phase shifters are the conventional approach of achieving beam steerable antennas. However, due to the insertion loss incurred by phase shifters and the high cost of acquiring phase shifters, alternative solutions that offers lower loss and cost are being researched. This work proposes two beam steerable antenna solutions that offer reduced insertion loss and cost. The first beam steering solution is a novel passive amplitude steering antenna that makes use of a reconfigurable ratio power divider instead of the conventional variable gain amplifiers for amplitude control. The designed antenna is a 2X1 antenna array which achieves continuous steering over the range 0 degree to 21 degrees in one direction. The second beam steering solution combines the parasitic steering technique with the phased array approach to form a hybrid parasitic antenna. The hybrid parasitic antenna was formed from a 3X1 phased antenna array surrounded by eight parasitic elements. The parasitic elements are operated by switches and the antenna achieved a fine steering resolution of 1 degree. Computer simulations were performed to assess the effect of using real switches and phase shifters within the antenna. To this effect, 3-bit phase shifters were incorporated into the hybrid parasitic antenna and its performance compared with that of a conventional 3X1 phased array incorporating 5-bits phase shifters. The realised gain of the hybrid parasitic antenna was 4 dB better than that of the conventional phased array. This suggests that the novel antenna offers significant improvement in antenna performance. This work also proposed a novel approach that improves the isolation bandwidth of a power divider which will be vital for phased arrays and MIMO applications. The compensated power divider achieves a 15 dB isolation bandwidth of 114% which is more than 40% of the isolation bandwidth of conventional Wilkinson power divider. This power divider solution is suitable for ultra-wideband frequency applications.
44
Hussain, Nizamudin. "Nizamudin Hussain, Performance Limitations and Estimates for Infinite Array Antennas." Thesis, KTH, Elektroteknisk teori och konstruktion, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-144898.
Abstract:
A novel quantitative measure for predicting the performance of arrays is tested on a few selected wide band arrays. This measure is called the array figure of merit. It is valid for lin-early polarized, infinite planar arrays, which are backed by a perfectly conducting ground plane. It predicts performance of arrays (which are free from grating lobes) in the E- or H-plane. The array figure of merit builds on the low frequency asymptotic expansion of the reflection coefficient and a sumrule of Rozanov type for passive structures. This measuretakes values between zero and one, and estimates array's performance on the basis of four key trade-off parameters:return loss, scan range, array thickness, and bandwidth. Arrays were found that yield values as high as 0.67, thus indicating a high performance array with respect to this measure. The sensitivity of the array figure of merit with respectto scan range is studied. Trade-off between bandwidth andreflection coefficient is investigated with respect to the ar-ray figure of merit. Finally an infinite array of stronglycoupled dipole elements is modeled and simulated. For this array, we test the sum rule based measure and find a veryhigh value for this measure: 0.84 - with 1 as its theoretical upper limit. This measurement reveals some insight into the influence of approximating material properties on the antenna performance measure.
45
Gonzalez, Francisco Javier. "Antenna-coupled infrared focal plane array." Doctoral diss., University of Central Florida, 2003. http://digital.library.ucf.edu/cdm/ref/collection/RTD/id/22899.
Abstract:
University of Central Florida College of Engineering ThesisIn this dissertation a new type of infared focal plan array (IR FPA) was investigated, consisting of antenna-coupled microbolometer fabricated using electron-beam lithography. Four different antenna designs were experimentally demonstrated at 10-micron wavelength: dipole, bowtie, square-spiral, and log-periodic. The main differences between these antenna types were their bandwidth, collection area, angular reception pattern, and polarization. To provide pixel collection areas commensurate with typical IR FPA requirements, two configuration were investigated: a two-dimensional serpentine interconnection of invididual IR antennas, and a Fresnel-zone-plate (FZP) coupled to a single-element antenna. Optimum spacing conditions for the two-dimensional interconnect were developed. Increased sensitivity was demonstrated using a FZP-coupled design. In general, it was found taht the configuration of the antenna substrate material was critical for optimization of sensitivity. The best results were obtained using this membranes of silicon nitride to enhance the thermal isolation of the antenna-coupled bolometers. In addition, choice of the bolometer material was also important, with the best results obtained using vanadium oxide. Using optimum choices for all parameters, normalized sensitivity (D*) values in the range of mid 108 [cm√Hz/W] were demonstrated for antenna-coupled IR sensors, and directions for further improvements were identified. Successful integration of antenna-coupled pixels with commercial readout integrated circuits was also demonstrated.
Ph.D.;
Electrical Engineering and Computer Science;
Engineering and Computer Science;
170 p.
xii, 170 leaves, bound : ill. ; 28 cm.
46
Bartee, Jon A. "Genetic algorithms as a tool for phased array radar design." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2002. http://library.nps.navy.mil/uhtbin/hyperion-image/02Jun%5FBartee.pdf.
47
Varum, Tiago Miguel Valente. "Nonuniform 2D microstrip antenna arrays for wireless applications." Doctoral thesis, Universidade de Aveiro, 2016. http://hdl.handle.net/10773/17373.
Abstract:
Doutoramento em Engenharia ElectrotécnicaWireless communications have undergone over the last decades a tremendous progress as a consequence of the exponential growth in demand for mobile devices, and nowadays are more and more involved in people's lives. This presence is re ected through the use of a large number of applications of which they become increasingly dependent on. The antenna, in its most di erent forms, are crucial elements in the establishment this type of communication. Each application involves a number of speci c characteristics, whereby, the improvement of wireless communications is related to the appropriateness of the used antenna. Many applications require antennas with radiation pattern with its particular shapes (in terms of beamwidth, side lobes levels, direction, etc ..), static or dynamic (adaptive antennas), involving in most cases the use antenna arrays to meet to such constraints. In this thesis, a number of techniques to synthesize antennas consisting of planar arrays with nonuniform excitation of their elements, are addressed. A group of the direction of arrival and beamforming estimation algorithms are also presented and analyzed, in order to enable their application in adaptive antenna array with dynamic beamforming. A vast and diversi ed set of arrays with di erent radiation requirements, and for di erent applications were developed. These arrays have great applicability in current research topics in antennas, such as vehicle communications, Wi-Fi in sports venues and smart antennas.
As comunicações sem os têm sofrido, ao longo das ultimas décadas, um enorme progresso em consequência do aumento exponencial da procura de dispositivos móveis, estando hoje em dia cada vez mais presentes na vida das pessoas. Esta presença re ete-se através do uso de um elevado número de aplicações das quais se tornam cada vez mais dependentes. As antenas, nas suas mais diversi cadas formas, são elementos cruciais no estabelecimento deste tipo de comunicações. Cada aplicação envolve um conjunto de características especí cas, pelo que a melhoria das comunica ções sem os está relacionada com a adequação da antena usada. Muitas aplicações necessitam de antenas com diagramas de radiação com formatos próprios (em termos de larguras de feixe, níveis de lobos secund ários, direção, etc..), sejam eles estáticos ou dinâmicos (antenas adaptativas), implicando na maioria dos casos o uso de agregados de antenas para fazer face a tais condições. Nesta tese são abordadas várias técnicas de desenho de antenas constituídas por agregados planares, com alimentação não uniforme dos seus elementos. Um conjunto de algoritmos de estimação dos ângulos de chegada e de formação de feixe são também apresentados e analisados com vista à sua aplicação em agregados de antenas adaptativas, com formação de feixe dinâmico. Um vasto e diversi cado conjunto de agregados com diferentes requisitos de radiação, destinados a diferentes aplicações foram desenvolvidos. Estes agregados têm grande aplicabilidade nos atuais tópicos de investiga ção em antenas, tais como as comunicações veiculares, Wi-Fi em espaços desportivos e smart antenas.
48
Hartup, David Carl. "Emitter identification using optical processors." Diss., Georgia Institute of Technology, 1991. http://hdl.handle.net/1853/15672.
49
Fofana, Seydouba. "Conception et mesure d'un réseau d'antennes reconfigurable sur la bande 3,4 - 3,8 GHz : contribution à la réduction de la consommation énergétique." Thesis, Rennes 1, 2020. http://www.theses.fr/2020REN1S031.
Abstract:
Cette thèse présente la conception, réalisation et mesure d’un réseau d’antennes reconfigurable dans la bande 3,4-3,8 GHz. Le réseau actif est composé de 16 dipôles à double polarisation qui peuvent rayonner un faisceau pouvant dépointer dans un plan sur un secteur angulaire de ±45°. Grâce à l’utilisation d’un générateur de signaux arbitraires, deux faisceaux pointant dans deux directions peuvent être rayonnés simultanément à deux fréquences différentes et reconfigurés à souhait. Ce réseau peut être vu comme un candidat pour de futurs systèmes de communication terrestre. Deux opérateurs mobiles pourraient alors partager le même réseau d’antennes. Les étapes de la conception du réseau sont détaillées progressivement, de l’élément unitaire, vers le réseau passif, puis reconfigurable par paquets, pour finir par le réseau complètement reconfigurable. La conception du réseau a eu pour ligne directrice la réduction de consommation d’énergie. Ainsi, des outils de synthèse ont été développés pour exploiter au mieux les caractéristiques de consommation des amplificateurs utilisés. De nombreux résultats de mesure valident les performances en rayonnement du réseau à chaque étape intermédiaire. De plus, ils montrent la réduction de consommation d’énergie réalisée et valident ainsi expérimentalement l’intérêt pratique des outils de synthèse développésThis thesis is dedicated to the design, manufacturing and characterization of a reconfigurable antenna array in the 3.4-3.8 GHz band. The active array is composed of 16 dual polarized dipoles that are able to radiate a beam steerable from ± 45° in a plane. Thanks to an arbitrary waveform generator, two beams can be radiated in two directions at two different frequencies simultaneously and can be reconfigured at will. This array can be seen as a candidate for future terrestrial communication systems. Two mobile network operators could then share the same antenna array. The steps of the array design are detailed showing the progression from the single antenna, to the passive array, the reconfigurable array by cluster to finish with the fully reconfigurable array. The array design has been driven by the reduction of the energy consumption. For that purpose, array synthesis tools have been developed to leverage at best the consumption characteristics of amplifiers. A number of measurement results validate experimentally the array radiation performances at each step of the design. Moreover, they demonstrate the achieved reduction of energy consumption and thus validate experimentally the practical interest of the developed synthesis tools
50
Cracraft, Michael Andrew. "Mobile array designs with ANSERLIN antennas and efficient, wide-band PEEC models for interconnect and power distribution network analysis." Diss., Rolla, Mo. : University of Missouri-Rolla, 2007. http://scholarsmine.umr.edu/thesis/pdf/mcthesis20070623_09007dcc80374999.pdf.
Abstract:
Thesis (Ph. D.)--University of Missouri--Rolla, 2007.Vita. The entire thesis text is included in file. Title from title screen of thesis/dissertation PDF file (viewed November 16, 2007) Includes bibliographical references (p. 134-136).