Author: Publisher:
ISBN:
Category :
Languages : en
Pages :
Book Description
Reflector Feeds for Large Adaptive Reflector Antennas
Author: Reflector Feeds for Large Adaptive Reflector Antennas
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.
Reflector Feeds for Large Adaptive Reflector Antennas
Author: Seyed Pedram Mousavi BafrooeiPublisher:
ISBN:
Category : Antennas, Reflector
Languages : en
Pages : 0
Book Description
Handbook of Reflector Antennas and Feed Systems Volume I: Theory and Design of Reflectors
Author: Satish K. SharmaPublisher: Artech House
ISBN: 160807515X
Category : Technology & Engineering
Languages : en
Pages : 323
Book Description
This is the first truly comprehensive and most up-to-date handbook available on modern reflector antennas and feed sources for diversified space and ground applications. There has never been such an all-encompassing reflector handbook in print, and no currently available title offers coverage of such recent research developments. The Handbook consists of three volumes. Volume I provides a unique combination of theoretical underpinnings with design considerations and techniques. The need for knowledge in reflector antennas has grown steadily over the last two decades due to increased use in space and ground applications, as well as their high gain and wide bandwidth capabilities at relatively low cost. This volume brings you to the leading edge of developments in the field related to numerical techniques, classical reflector geometries, adaptive reflector antennas, shaped reflectors, bifocal and bicollimated dual reflectors, advanced reflectors, and reflect arrays. A must-have reference for both practicing engineers as well as academic researchers.
Handbook of Reflector Antennas and Feed Systems Volume II: Feed Systems
Author: Lotfollah ShafaiPublisher: Artech House
ISBN: 1608075176
Category : Technology & Engineering
Languages : en
Pages : 381
Book Description
This is the first truly comprehensive and most up-to-date handbook available on modern reflector antennas and feed sources for diversified space and ground applications. There has never been such an all-encompassing reflector handbook in print, and no currently available title offers coverage of such recent research developments. The Handbook consists of three volumes. Volume II focuses on feed sources. Reflector antennas are extraordinary devices that combine high gain with geometrical simplicity, and can operate in broad frequency bands. Their performance, however, depends on the electrical characteristics of the feed system with which they operate. This comprehensive volume provides you with a solid understanding of feed system theory, design, and analysis. Featuring chapters authored by experts in each aspect of feed systems, this book takes you from fundamental mathematical techniques, electrically small and large dual reflectors, feed geometry and telemetry, tracking and command antennas, and more. Throughout the book numerous examples are provided to guide you in the practical aspects of feed design.
The Paraboloidal Reflector Antenna in Radio Astronomy and Communication
Author: Jacob W. M. BaarsPublisher: 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.
Handbook of Reflector Antennas and Feed Systems Volume III: Applications of Reflectors
Author: Sudhakar RaoPublisher: Artech House
ISBN: 1608075192
Category : Technology & Engineering
Languages : en
Pages : 462
Book Description
This is the first truly comprehensive and most up-to-date handbook available on modern reflector antennas and feed sources for diversified space and ground applications. There has never been such an all-encompassing reflector handbook in print, and no currently available title offers coverage of such recent research developments. The Handbook consists of three volumes. Volume III focuses on the range of reflector antenna applications, including space, terrestrial, and radar. The intent of this book volume is to provide practical applications and design information on reflector antennas used for several communications systems. This book covers recent developments of reflector antennas used for satellite communications, terrestrial communications, and remote sensing applications. New subjects are introduced for the first time, including satellite antennas, Terahertz antennas, PIM, multipaction, corona, deployable mesh reflector antennas, and mechanical aspects of reflector antennas. In addition, this book contains a separate topic on integrated feed assembly for reflector antennas covering analysis, design, fabrication, and test.
Adaptive Primary Feeds for Phase Error Compensation in Parabolic Reflector Antennae
Author: A. W. RudgeGenetic Algorithms in Electromagnetics
Author: Randy L. HauptPublisher: John Wiley & Sons
ISBN: 0470106271
Category : Science
Languages : en
Pages : 317
Book Description
A thorough and insightful introduction to using genetic algorithms to optimize electromagnetic systems Genetic Algorithms in Electromagnetics focuses on optimizing the objective function when a computer algorithm, analytical model, or experimental result describes the performance of an electromagnetic system. It offers expert guidance to optimizing electromagnetic systems using genetic algorithms (GA), which have proven to be tenacious in finding optimal results where traditional techniques fail. Genetic Algorithms in Electromagnetics begins with an introduction to optimization and several commonly used numerical optimization routines, and goes on to feature: Introductions to GA in both binary and continuous variable forms, complete with examples of MATLAB(r) commands Two step-by-step examples of optimizing antenna arrays as well as a comprehensive overview of applications of GA to antenna array design problems Coverage of GA as an adaptive algorithm, including adaptive and smart arrays as well as adaptive reflectors and crossed dipoles Explanations of the optimization of several different wire antennas, starting with the famous "crooked monopole" How to optimize horn, reflector, and microstrip patch antennas, which require significantly more computing power than wire antennas Coverage of GA optimization of scattering, including scattering from frequency selective surfaces and electromagnetic band gap materials Ideas on operator and parameter selection for a GA Detailed explanations of particle swarm optimization and multiple objective optimization An appendix of MATLAB code for experimentation
Author: Lyle C. Schroeder