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Author: Jacob W. M. Baars Publisher: Springer Science & Business Media ISBN: 0387697349 Category : Science Languages : en Pages : 270
Book Description
Radio astronomers have developed techniques of calibration of large reflector antennas with radio astronomical methods, but these have not been comprehensively described. This text aims to fill this gap, taking a practical approach to the characterisation of antennas. All calculations and results in the form of tables and figures have been made with Mathematica by Wolfram Research. The reader can use the procedures for the implementation of his own input data.
Author: Jacob W. M. Baars Publisher: Springer Science & Business Media ISBN: 0387697349 Category : Science Languages : en Pages : 270
Book Description
Radio astronomers have developed techniques of calibration of large reflector antennas with radio astronomical methods, but these have not been comprehensively described. This text aims to fill this gap, taking a practical approach to the characterisation of antennas. All calculations and results in the form of tables and figures have been made with Mathematica by Wolfram Research. The reader can use the procedures for the implementation of his own input data.
Author: Jacob W. M. Baars Publisher: Springer ISBN: 9780387517728 Category : Science Languages : en Pages : 0
Book Description
Radio astronomers have developed techniques of calibration of large reflector antennas with radio astronomical methods, but these have not been comprehensively described. This text aims to fill this gap, taking a practical approach to the characterisation of antennas. All calculations and results in the form of tables and figures have been made with Mathematica by Wolfram Research. The reader can use the procedures for the implementation of his own input data.
Author: Jacob W.M. Baars Publisher: Springer ISBN: 331965148X Category : Science Languages : en Pages : 282
Book Description
This book demonstrates how progress in radio astronomy is intimately linked to the development of reflector antennas of increasing size and precision. The authors describe the design and construction of major radio telescopes as those in Dwingeloo, Jodrell Bank, Parkes, Effelsberg and Green Bank since 1950 up to the present as well as millimeter wavelength telescopes as the 30m MRT of IRAM in Spain, the 50m LMT in Mexico and the ALMA submillimeter instrument. The advances in methods of structural design and coping with environmental influences (wind, temperature, gravity) as well as application of new materials are explained in a non-mathematical, descriptive and graphical way along with the story of the telescopes. Emphasis is placed on the interplay between astronomical and electromagnetic requirements and structural, mechanical and control solutions. A chapter on management aspects of large telescope projects closes the book. The authors address a readership with interest in the progress of engineering solutions applied to the development of radio telescope reflectors and ground station antennas for satellite communication and space research. The book will also be of interest to historians of science and engineering with an inclination to astronomy.
Author: A. Richard Thompson Publisher: Springer ISBN: 331944431X Category : Science Languages : en Pages : 910
Book Description
This book is open access under a CC BY-NC 4.0 license. The third edition of this indispensable book in radio interferometry provides extensive updates to the second edition, including results and technical advances from the past decade; discussion of arrays that now span the full range of the radio part of the electromagnetic spectrum observable from the ground, 10 MHz to 1 THz; an analysis of factors that affect array speed; and an expanded discussion of digital signal-processing techniques and of scintillation phenomena and the effects of atmospheric water vapor on image distortion, among many other topics. With its comprehensiveness and detailed exposition of all aspects of the theory and practice of radio interferometry and synthesis imaging, this book has established itself as a standard reference in the field. It begins with an overview of the basic principles of radio astronomy, a short history of the development of radio interferometry, and an elementary discussion of the operation of an interferometer. From this foundation, it delves into the underlying relationships of interferometry, sets forth the coordinate systems and parameters to describe synthesis imaging, and examines configurations of antennas for multielement synthesis arrays. Various aspects of the design and response of receiving systems are discussed, as well as the special requirements of very-long-baseline interferometry (VLBI), image reconstruction, and recent developments in image enhancement techniques and astrometric observations. Also discussed are propagation effects in the media between the source and the observer, and radio interference, factors that limit performance. Related techniques are introduced, including intensity interferometry, optical interferometry, lunar occultations, tracking of satellites in Earth orbit, interferometry for remote Earth sensing, and holographic measurements of antenna surfaces. This book will benefit anyone who is interested in radio interferometry techniques for astronomy, astrometry, geodesy, or electrical engineering.
Author: Karl F. Warnick Publisher: Cambridge University Press ISBN: 1108540287 Category : Science Languages : en Pages : 471
Book Description
Discover a modern approach to the analysis, modeling and design of high sensitivity phased arrays. Network theory, numerical methods and computational electromagnetic simulation techniques are uniquely combined to enable full system analysis and design optimization. Beamforming and array signal processing theory are integrated into the treatment from the start. Digital signal processing methods such as polyphase filtering and RFI mitigation are described, along with technologies for real-time hardware implementation. Key concepts from interferometric imaging used in radio telescopes are also considered. A basic development of theory and modeling techniques is accompanied by problem sets that guide readers in developing modeling codes that retain the simplicity of the classical array factor method while incorporating mutual coupling effects and interactions between elements. Combining current research trends with pedagogical material suitable for a first-year graduate course, this is an invaluable resource for students, teachers, researchers, and practicing RF/microwave and antenna design engineers.
Author: Bernard F. Burke Publisher: Cambridge University Press ISBN: 1108100279 Category : Science Languages : en Pages : 545
Book Description
Radio astronomy is an active and rapidly expanding field due to advances in computing techniques, with several important new instruments on the horizon. This text provides a thorough introduction to radio astronomy and its contribution to our understanding of the universe, bridging the gap between basic introductions and research-level treatments. It begins by covering the fundamentals physics of radio techniques, before moving on to single-dish telescopes and aperture synthesis arrays. Fully updated and extensively rewritten, the fourth edition places greater emphasis on techniques, with detailed discussion of interferometry in particular, and comprehensive coverage of digital techniques in the appendices. The science sections are fully revised, with new author Peter N. Wilkinson bringing added expertise to the sections on pulsars, quasars and active galaxies. Spanning the entirety of radio astronomy, this is an engaging introduction for students and researchers approaching radio astronomy for the first time.
Author: Publisher: ISBN: Category : Languages : en Pages :
Book Description
A novel Feed-Reflector system for large Cassegrain antennas for Radio Astronomy and Deep-Space Communication applications is investigated. This Feed-Reflector is used to illuminate a hyperboloid sub-reflector with 5-10 m diameter located 500 m above the ground. Because the sub-reflector is located in the near field of the Feed-Reflector antenna, a theory based on the near field focusing properties of paraboloid reflectors is established. The focusing at near distance is formed by moving the feed horn away from the focal point of the Feed-Reflector. In this theory the properties of axial defocused paraboloid reflectors at near distance are investigated in some detail. By using equivalence path law, sub-reflector shape is obtained. It is found that the hyperbola can approximate the sub-reflector well. A detailed ray tracing analysis is performed on the entire system which reveals that some part of the sub-reflector receive three rays per point from the feed. The performance of the system over the operating band (1-22 GHz) is also studied and shown that the lower frequency limit is dependent on sub-reflector and Feed-Reflector sizes. To obtain higher efficiencies, three sets of shaping techniques, based on the genetic algorithm and Jacobi Fourier surface expansion, are performed. An efficiency of 78.5% for a 5 m sub-reflector is obtained. In another method of analysis, the Feed-Reflector aperture field distribution is expanded into a set of Gaussian-Laguerre modes. These modes propagate from the Feed-Reflector aperture in a simple and well defined way. The Feed-Reflector near field radiation pattern is calculated at the sub-reflector location. The sub-reflector parameters in this system are found by maximizing the Large Adaptive Reflector (LAR) aperture efficiency which includes phase and taper efficiencies, and minimizing the LAR spillover loss. An exact equation for the offset LAR surface is obtained in this thesis. To scan the beam up to 60, which is one of the LAR.
Author: James J. Condon Publisher: Princeton University Press ISBN: 069113779X Category : Science Languages : en Pages : 376
Book Description
The ideal text for a one-semester course in radio astronomy Essential Radio Astronomy is the only textbook on the subject specifically designed for a one-semester introductory course for advanced undergraduates or graduate students in astronomy and astrophysics. It starts from first principles in order to fill gaps in students' backgrounds, make teaching easier for professors who are not expert radio astronomers, and provide a useful reference to the essential equations used by practitioners. This unique textbook reflects the fact that students of multiwavelength astronomy typically can afford to spend only one semester studying the observational techniques particular to each wavelength band. Essential Radio Astronomy presents only the most crucial concepts—succinctly and accessibly. It covers the general principles behind radio telescopes, receivers, and digital backends without getting bogged down in engineering details. Emphasizing the physical processes in radio sources, the book's approach is shaped by the view that radio astrophysics owes more to thermodynamics than electromagnetism. Proven in the classroom and generously illustrated throughout, Essential Radio Astronomy is an invaluable resource for students and researchers alike. The only textbook specifically designed for a one-semester course in radio astronomy Starts from first principles Makes teaching easier for astronomy professors who are not expert radio astronomers Emphasizes the physical processes in radio sources Covers the principles behind radio telescopes and receivers Provides the essential equations and fundamental constants used by practitioners Supplementary website includes lecture notes, problem sets, exams, and links to interactive demonstrations An online illustration package is available to professors