Thinning and Broadbanding Antenna Arrays by Unequal Spacings PDF Download
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Author: Akira Ishimaru
Publisher:
ISBN:
Category : Antenna arrays
Languages : en
Pages : 42
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Book Description
The paper presents a theory for, and a method of designing a thinned or broadband antenna array by means of unequal spacings. Using the theory of unequally spaced arrays developed by one of the authors, an antenna array can be designed to produce a desired beamwidth and sidelobe level with the average spacing many wavelengths apart. The patterns are expressed in a series of the Anger functions and its sidelobe level is shown to decrease approximately as N to the minus 0.4th power where N is the total number of elements, and the gain is approximately equal to N. It is also shown that the sidelobe level can be improved by varying the amplitude distribution. Numerical examples are given to illustrate the method. (Author).
Author: Akira Ishimaru
Publisher:
ISBN:
Category : Antenna arrays
Languages : en
Pages : 42
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Book Description
The paper presents a theory for, and a method of designing a thinned or broadband antenna array by means of unequal spacings. Using the theory of unequally spaced arrays developed by one of the authors, an antenna array can be designed to produce a desired beamwidth and sidelobe level with the average spacing many wavelengths apart. The patterns are expressed in a series of the Anger functions and its sidelobe level is shown to decrease approximately as N to the minus 0.4th power where N is the total number of elements, and the gain is approximately equal to N. It is also shown that the sidelobe level can be improved by varying the amplitude distribution. Numerical examples are given to illustrate the method. (Author).
Author: Yung Sen Chen
Publisher:
ISBN:
Category : Antenna arrays
Languages : en
Pages : 92
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Book Description
Author: Yung Sen Chen
Publisher:
ISBN:
Category : Antenna arrays
Languages : en
Pages : 96
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Book Description
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: Y.T. Lo
Publisher: Springer Science & Business Media
ISBN: 146156459X
Category : Technology & Engineering
Languages : en
Pages : 2282
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Book Description
Techniques based on the method of modal expansions, the Rayleigh-Stevenson expansion in inverse powers of the wavelength, and also the method of moments solution of integral equations are essentially restricted to the analysis of electromagnetic radiating structures which are small in terms of the wavelength. It therefore becomes necessary to employ approximations based on "high-frequency techniques" for performing an efficient analysis of electromagnetic radiating systems that are large in terms of the wavelength. One of the most versatile and useful high-frequency techniques is the geometrical theory of diffraction (GTD), which was developed around 1951 by J. B. Keller [1,2,3]. A class of diffracted rays are introduced systematically in the GTD via a generalization of the concepts of classical geometrical optics (GO). According to the GTD these diffracted rays exist in addition to the usual incident, reflected, and transmitted rays of GO. The diffracted rays in the GTD originate from certain "localized" regions on the surface of a radiating structure, such as at discontinuities in the geometrical and electrical properties of a surface, and at points of grazing incidence on a smooth convex surface as illustrated in Fig. 1. In particular, the diffracted rays can enter into the GO shadow as well as the lit regions. Consequently, the diffracted rays entirely account for the fields in the shadow region where the GO rays cannot exist.
Author: Ashutosh Kedar
Publisher: Artech House
ISBN: 1630818798
Category : Technology & Engineering
Languages : en
Pages : 315
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Book Description
This ground-breaking resource gives you the background theories and know-how you need to effectively design active phased array antennas with wider bandwidth and scan volume utilizing sparse array technology. The book shows you how to incorporate aperiodic arrays and sparse arrays as a solution for overcoming the restrictions faced in conventional phased antenna designs – such as blind spots, limited scan volume, large power and cooling requirements, RF path losses, and increased complexity – while adhering to the maintenance of SWAP-C resources widely used in aerospace and defence. Packed with step-by-step information and research results unavailable in any other single source to date, the book presents new concepts and techniques that potentially can be applied to many critical defense and commercial requirements such as: radars, satcom on move, sonars, weather monitoring, 5G and 6G for mobile communication, fault and crack detection in buildings and underground pipelines, automotive anti-collisions mechanism in automobiles, mine detection, through wall imaging, and more. The book helps you to understand the fundamental antenna technology being deployed in modern systems and equips you to design problem-solving sparse array models proven by electromagnetic simulations that can reduce the cost and overall complexity of the existing systems. Numerous design studies are documented to validate the theories presented. The book takes into account the functional constraints in designing commercial and military systems while demonstrating provable techniques that are practical and achievable. This is an important resource for phased array antenna designers interested in utilizing sparse array technology with wider bandwidth and scan volume. The book’s straightforward approach and easy-to-follow language also make it accessible to students and those new to the field.
Author: Constantine A. Balanis
Publisher: John Wiley & Sons
ISBN: 1118209753
Category : Technology & Engineering
Languages : en
Pages : 1617
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Book Description
The most up-to-date, comprehensive treatment of classical and modern antennas and their related technologies Modern Antenna Handbook represents the most current and complete thinking in the field of antennas. The handbook is edited by one of the most recognizable, prominent, and prolific authors, educators, and researchers on antennas and electromagnetics. Each chapter is authored by one or more leading international experts and includes cover-age of current and future antenna-related technology. The information is of a practical nature and is intended to be useful for researchers as well as practicing engineers. From the fundamental parameters of antennas to antennas for mobile wireless communications and medical applications, Modern Antenna Handbook covers everything professional engineers, consultants, researchers, and students need to know about the recent developments and the future direction of this fast-paced field. In addition to antenna topics, the handbook also covers modern technologies such as metamaterials, microelectromechanical systems (MEMS), frequency selective surfaces (FSS), and radar cross sections (RCS) and their applications to antennas, while five chapters are devoted to advanced numerical/computational methods targeted primarily for the analysis and design of antennas.
Author: Moeness G. Amin
Publisher: John Wiley & Sons
ISBN: 1394191014
Category : Technology & Engineering
Languages : en
Pages : 516
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Book Description
Specialized resource providing detailed coverage of recent advances in theory and applications of sparse arrays Sparse Arrays for Radar, Sonar, and Communications discusses various design approaches of sparse arrays, including those seeking to increase the corresponding one-dimensional and two-dimensional virtual array apertures, as well as others that configure the arrays based on solutions of constrained minimization problems. The latter includes statistical bounds and signal-to-interference and noise ratio; in this respect, the book utilizes the recent strides made in convex optimizations and machine learning for sparse array configurability in both fixed and dynamic environments. Similar ideas are presented for sparse array-waveform design. The book also discusses the role of sparse arrays in improving target detection and resolution in radar, improving channel capacity in massive MIMO, and improving underwater target localization in sonar. It covers different sparse array topologies, and provides various approaches that deliver the optimum and semi-optimum sparse array transceivers. . Edited by a world-leading expert in Radar and Signal Processing and contributed to by world-class researchers in their respective fields, Sparse Arrays for Radar, Sonar, and Communications covers topics including: Utilizing sparse arrays in emerging technologies and showing their offerings in various sensing and communications applications Applying sparse arrays to different environments and obtain superior performances over conventional uniform arrays Solving the localization, beamforming, and direction-finding problems using non-uniform array structures for narrowband and wideband signals Designing sparse array structures for both stationary and moving platforms that produce physical and synthesized array apertures. Using deep neural networks that learn the underlying complex nonlinear model and output the sparse array configuration using representations of the input data spatio-temporal observations Solving for optimum sparse array configurations and beamforming coefficients in sensing using iterative convex optimization methods Providing complete coverage of the recent considerable progress in sparse array design and configurations, Sparse Arrays for Radar, Sonar, and Communications is an essential resource on the subject for graduate students and engineers pursuing research and applications in the broad areas of active/passive sensing and communications.
Author:
Publisher:
ISBN:
Category : Science
Languages : en
Pages : 1076
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Book Description
Author:
Publisher:
ISBN:
Category : Aeronautics
Languages : en
Pages : 1828
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Book Description
