Author: Daniel Robert Richards
Publisher:
ISBN: 9781423535744
Category : Space-based radar
Languages : en
Pages : 139
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Book Description
This thesis provides a method to reduce physical resource requirements along with cost reduction in Space Based Radar (SBR) platforms, and provides a rule of thumb for randomization effects on arrays. A trend analysis is performed on 4, 8, 12, and 16 square meter arrays. Three aperiodic thinning approaches are examined. They are an equal current density element distribution, a random periodic grid of elements, and random element distribution based a peak sidelobe indicator. According to the metrics used, the statistical and deterministic array thinning approaches performed best for these small arrays. However, the statistical arrays have a scan angle limitation of 00=300 due to the interelement spacing of two wavelengths. The deterministic does poorly with peak sidelobes. The random array performance was limited due to the relatively small array sizes for the random approach used. The small size limits the array's capability to meet the peak sidelobe threshold requirement, due to a reduced confidence level, along with limiting the effective area to be randomized. However, as the array size increased, the thinning levels and performance increased to become competitive with the other array approaches. If trends continue as array size increases, the random array is the ideal solution.
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 139
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Book Description
This thesis provides a method to reduce physical resource requirements along with cost reduction in Space Based Radar (SBR) platforms, and provides a rule of thumb for randomization effects on arrays. A trend analysis is performed on 4, 8, 12, and 16 square meter arrays. Three aperiodic thinning approaches are examined. They are an equal current density element distribution, a random periodic grid of elements, and random element distribution based a peak sidelobe indicator. According to the metrics used, the statistical and deterministic array thinning approaches performed best for these small arrays. However, the statistical arrays have a scan angle limitation of 00=300 due to the interelement spacing of two wavelengths. The deterministic does poorly with peak sidelobes. The random array performance was limited due to the relatively small array sizes for the random approach used. The small size limits the array's capability to meet the peak sidelobe threshold requirement, due to a reduced confidence level, along with limiting the effective area to be randomized. However, as the array size increased, the thinning levels and performance increased to become competitive with the other array approaches. If trends continue as array size increases, the random array is the ideal solution.
Author: Jafar Ramadhan Mohammed
Publisher: BoD – Books on Demand
ISBN: 1789857414
Category : Technology & Engineering
Languages : en
Pages : 122
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Book Description
Array pattern optimization is a very important and necessary issue in the majority of modern communication systems in a variety of applications such as sonar, radar, navigation, wireless communications, and many other engineering fields. Classical methods for array pattern synthesis have worked mainly with analytical models that are linear, local and, thus, their performances were not optimum. They have always been designed with closed-form mathematical models. Unlike these analytical methods, the global optimization methods with powerful computing tools offer optimum solutions. During the last few years, the design of the antenna arrays has been a topic of significant research activity. This book presents recent advances in the field of array pattern optimization. It is targeted primarily toward students and researchers who want to be exposed to a wide variety of antenna array design and optimization. It includes five chapters as well as the introductory chapter. These five chapters are categorized into five different areas depending on the application. These applications are ordered to address interference suppression, electronic toll collection, mmWave and ultra-wideband, integrated antennas, and educational packages for modeling smart antenna for 5G wireless communications. The book has the advantage of providing a collection of applications that are entirely independent and self-contained; thus, the interested reader can choose any chapter and skip to another without losing continuity.
Author: Harvey K. Schuman
Publisher:
ISBN:
Category : Antenna arrays
Languages : en
Pages : 156
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Book Description
Analytical techniques presented thus far for treatment of unequally spaced antenna arrays have pointed out that desirable radiation characteristics can be achieved using only the interelement spacings as design parameters. The advantage is that the excitation amplitudes required can be either uniform or nearly uniform across the array, thereby allowing use of a simple feed system for excitation of the array elements and minimizing adverse mutual coupling effects. The design methods have found only limited applications, however, since results are not always reliable due to the approximations necessary to simplify the analytical work. Various computational methods have been presented to circumvent this problem, but these in turn suffer disadvantage in that they provide no control over the ultimate positions of the array elements, giving rise to unrealistic spacing configurations and severe realization problems through mutual coupling. In this work a new computational technique is presented for designing unequally spaced arrays. The method is particularly suitable for use with modern high-speed electronic computers, and allows certain practical restrictions or constraints to be included in the design procedure by allowing use of a limited number of different excitation amplitude levels. The result in any given example is an unequally spaced linear array designed for a specified sidelobe level, with a number of amplitude levels appropriate for insuring that prespecified spacing restrictions are met. Thus, the practical difficulties encountered with the results of other computational schemes are largely avoided. Several examples are given, and both theoretical and experimental results are included. (Author).
Author: Hema Singh
Publisher: Cambridge University Press
ISBN: 1107092612
Category : History
Languages : en
Pages : 354
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Book Description
This book discusses the active and passive radar cross section (RCS) estimation and techniques to examine the low observable aerospace platforms. It begins with the fundamentals of RCS, followed by the dielectric, magnetic and metamaterials parameters of the constituent materials and then explains various methods and the emerging trends followed in this area of study. The RCS estimation of phased array including the mutual coupling effect is also presented in detail in the book. The active RCS reduction is carefully touched upon through the performance of phased arrays, sidelobe cancellers and mitigation of multipath effect. Providing information on various adaptive algorithms like least mean square (LMS), recursive least square (RLS) and weighted least square algorithms, the authors also mention the recent developments in the area of embedded antennas, conformal load bearing antenna, metamaterials and frequency selective surface (FSS) based RCS reduction.
Author: John Sahalos
Publisher: John Wiley & Sons
ISBN: 047002853X
Category : Technology & Engineering
Languages : en
Pages : 228
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Book Description
The first time that such a complete systematic analysis of the mathematical and numerical techniques related to the orthogonal methods has been given. With the explosion of the wireless world, greater emphasis than ever before is being placed on the effective design of antennas. Orthogonal Methods for Array Synthesis outlines several procedures of orthogonal methods suitable for antenna array synthesis. The book presents a simple approach to the design of antenna arrays to enable the reader to use the classical Orthogonal Method for synthesis of linear arrays. This theory-based book, which includes rapid, effective solutions to design problems for communications applications and broadcasting, is amply illustrated with real-world examples and case studies. Also included in the book is the ORAMA MS Windows-compatible computer tool, patented by Professor Sahalos and his team. Provides comprehensive coverage of the basic principles of orthogonal methods including an analytical explanation of the orthogonal method (OM) and the orthogonal perturbation method (OP) Gives rapid, cost-effective solutions to antenna design problems for communications applications and broadcasting Illustrates all theory with practical applications gleaned from the author’s extensive experience in the field of orthogonal advanced methods for antennas Providing a complete guide to the theory and applications of the Orthogonal Methods, this book is a must-read for antenna engineers and graduate students of electrical and computer engineering and physics.
Author: Martin Schwam
Publisher:
ISBN:
Category : Antenna arrays
Languages : en
Pages : 376
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Book Description
Author: Randy L. Haupt
Publisher: John Wiley & Sons
ISBN: 9780470937433
Category : Technology & Engineering
Languages : en
Pages : 534
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Book Description
A comprehensive tutorial on the design and practical applications of antenna arrays An antenna array is an assembly of antenna elements that maximizes a received or transmitted signal in a desired direction. This practical book covers a wide range of antenna array topics that are becoming increasingly important in wireless applications, with emphasis on array design, applications, and computer modeling. Each chapter in Antenna Arrays builds upon the previous chapter, progressively addressing more difficult material. Beginning with basic electromagnetics/antennas/antenna systems information, the book then deals with the analysis and synthesis of arrays of point sources and their associated array factors. It presents a sampling of different antenna elements that replace these point sources, then presents element configurations that do not have to lie along a line or in a plane. The complex and difficult-to-predict interactions of elements and electromagnetic waves are introduced, along with computer modeling and experiments that are necessary for predicting the performance of arrays where mutual coupling is important. Then, various approaches to getting signals to and from the array elements to a computer where the signal detection takes place are explored, as are the numerical techniques behind smart antennas. The book emphasizes the computational methods used in the design and analysis of array antennas. Also featured are signal processing and numerical modeling algorithms, as well as pictures of antenna arrays and components provided by industry and government sources, with explanations of how they operate. Fully course-tested, Antenna Arrays serves as a complete text in phased array design and theory for advanced undergraduate- and graduate-level courses in electronics and communications, as well as a reference for practicing engineers and scientists in wireless communications, radar, and remote sensing.
Author: Nicholas Fourikis
Publisher: Academic Press
ISBN: 9780122629426
Category : Computers
Languages : en
Pages : 394
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Book Description
Advanced Array Systems, Applications and RF Technologies adopts a holistic view of arrays used in radar, electronic warfare, communications, remote sensing and radioastronomy. Radio frequency [RF] and intermediate frequency [IF] signal processing is assuming a fundamental importance, owing to its increasing ability to multiply a system's capabilities in a cost-effective manner. This book comprehensively covers the important front-end RF subsystems of active phased arrays, so offering array designers new and exciting opportunities in signal processing. This book: * provides an up to date record of existing systems from different applications * explores array systems under development * bridges the gap between textbook coverage of idealized phased arrays and practical knowledge of working phased arrays * recognises the significance of cost to the realization of phased arrays * discusses future advances in the field that promise to deliver even more affordable arrays ['intelligent' or self-focussing/-cohering arrays] Engineers and scientists in the radar and RF technology industry will welcome the detailed description of array elements, polarisers, T/R modules and beamformers in Advanced Array Systems, Applications and RF Technologies. This book is also appropriate for postgraduate and advanced undergraduate students in electronic engineering, and for technical managers, researchers and students in the fields of radioastronomy and remote sensing. This book is a volume in the Signal Processing and its Applications series, edited by Richard Green and Truong Nguyen.
Author: Charles J. Drane (Jr.)
Publisher:
ISBN:
Category : Antenna arrays
Languages : en
Pages : 44
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Book Description
This is a theoretical study of certain optimum linear arrays of nonuniformly spaced, isotropic antennas. For this purpose, the beamwidth of any given radiation pattern is defined in a new, integral sense, with low values denoting highly directional radiation patterns with low sidelobes. The present work is almost wholly concerned with the choice of (1) the excitation currents, and (2) the locations of individual antennas to minimize this particular beamwidth. It is shown that the first of these two choices reduces to a straightforward eigenvalue problem involving symmetric matrices. The search for the optimum element locations, however, requires also a knowledge of the derivatives of this 'best' beamwidth with respect to changes in the element spacings, together with some hunting procedure to arrive at configurations for which all those are zero. In the present computations, the latter consisted of a step-by-step procedure wherein the locally optimum beamwidth and its derivatives for any given array were first computed via the matrices, and successive neighboring configurations were then defined automatically with the elements shifted by amounts (of prescribed total magnitude) calculated to reduce the beamwidth as much as possible at every step. Numerical results of these computations are here presented for arrays ranging from four to forty symmetrically placed elements. On the whole, they seem to indicate that the best configurations in cases where the overall aperture is not constrained are ones in which the elements are spaced very nearly uniformly, with separations of the order of 0.8 to 0.9 times the wavelength. (Author).
