Download or read book Design and Operation of Antennas at the Ion Cyclotron and Lower Hybrid Range of Frequencies for Nuclear Fusion Reactors written by Walid Helou and published by . This book was released on 2017 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The thesis provides at first a brief introduction to magnetic nuclear fusion and tokamaks. It explains the need for auxiliary plasma heating and current-drive electromagnetic systems at the Ion Cyclotron and Lower Hybrid Range of Frequencies (ICRF and LHRF). The thesis then sets antenna specifications that allow satisfying proper plasma wave propagation and proper wave-particle resonance. The Radio Frequency (RF) network solver SIDON developed for this thesis is then presented. The thesis then discusses the different types of ICRF antennas and details the challenges of the impedance matching in ICRF arrays of straps. WEST ICRF launchers are discussed in great detail and simulations of impedance matching scenarios for these launchers using SIDON are reported. The thesis reports on the low-power (milliwatt range) testbed that has been developed for WEST ICRF launchers, as well as the low-power tests of the first one among them. Furthermore, high power (megawatt range) experiments on plasma with the JET ICRF ITER-Like Antenna are reported. The thesis then provides an overview about existing LHRF antennas and discusses the numerical modeling of the coupling of waveguide phased arrays to the plasma. The RF design of ASTARTE-LP and its feeding circuit is discussed. ASTARTE-LP is a low-power (milliwatt range) prototype LHRF antenna based on the Slotted Waveguide Antenna concept that has been designed and built to perform proof of principle experiments on the COMPASS tokamak. The experimental validation of ASTARTE-LP and its feeding circuit before the experiments on COMPASS, as well as the experiments performed on COMPASS plasmas are reported.

Download or read book Design and Control of Phased ICRF Antenna Arrays written by and published by . This book was released on 1993 with total page 5 pages. Available in PDF, EPUB and Kindle. Book excerpt: Phased antenna arrays operating in the ion cyclotron range of frequencies (ICRF) are used to produce highly directional wave spectra, primarily for use in current drive experiments. RF current drive using phased antennas has been demonstrated in both the JET and DIII-D tokamaks, and both devices are planning to operate new four-element arrays beginning early next year. Features of antenna design that are relevant to phased operation and production of directional spectra are reviewed. Recent advances in the design of the feed circuits and the related control systems for these arrays should substantially improve their performance, by reducing the coupling seen by the matching networks and rf power supplies caused by the mutual impedance of the array elements. The feed circuit designs for the DIII-D and JET phased antenna arrays are compared. The two configurations differ significantly due to the fact that one power amplifier is used for the entire array in the former case, and one per element in the latter. The JET system uses automatic feedback control of matching, phase and amplitude of antenna currents, and the transmitter power balance. The design of this system is discussed, and a time dependent model used to predict its behavior is described.

Download or read book Fusion Energy Update written by and published by . This book was released on 1982 with total page 72 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Energy Research Abstracts written by and published by . This book was released on 1993-08 with total page 472 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Antennas for the Radio Frequency Heating of Plasmas on Fusion Research Devices in the Ion Cyclotron Range of Frequencies written by and published by . This book was released on 1994 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Three dimensional Antenna Models for Fusion Experiments written by and published by . This book was released on 1995 with total page 5 pages. Available in PDF, EPUB and Kindle. Book excerpt: The development of the RANT3D code has permitted the systematic study Of the effect of three-dimensional structures on the launched power spectrum for antennas in the ion cyclotron range of frequencies. The code allows the septa between current straps to be modeled with arbitrary heights and permits the antenna to interact with other structures in the tokamak. In this paper we present comparisons of calculated loading with the Tokamak Fusion Test Reactor and Tore Supra experiments, demonstrate the effects on loading caused by positioning uncertainties for an antenna in Tore Supra, and show electric field patterns near the Tore Supra antenna. A poloidal component in the static magnetic field for the plasma response is included in the near-field calculations using the warm plasma code, GLOSI. Preliminary estimates for the heat flux on the bumper limiters during typical operation in Tore Supra are also presented.

Download or read book Chemical Abstracts written by and published by . This book was released on 2002 with total page 2018 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Reflectarray Antennas written by Payam Nayeri and published by John Wiley & Sons. This book was released on 2018-02-23 with total page 729 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book provides engineers with a comprehensive review of the state-of-the-art in reflectarray antenna research and development. The authors describe, in detail, design procedures for a wide range of applications, including broadband, multi-band, multi-beam, contour-beam, beam-scanning, and conformal reflectarray antennas. They provide sufficient coverage of basic reflectarray theory to fully understand reflectarray antenna design and analysis such that the readers can pursue reflectarray research on their own. Throughout the book numerous illustrative design examples including numerical and experimental results are provided. Featuring in-depth theoretical analysis along with practical design examples, em style="mso-bidi-font-style: normal;"Reflectarray Antennas is an excellent text/reference for engineering graduate students, researchers, and engineers in the field of antennas. It belongs on the bookshelves of university libraries, research institutes, and industrial labs and research facilities.

Download or read book Terahertz Planar Antennas for Next Generation Communication written by Kumud Ranjan Jha and published by Springer Science & Business Media. This book was released on 2014-01-10 with total page 221 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book describes various methods to enhance the directivity of planar antennas, enabling the next generation of high frequency, wireless communication. The authors discuss various applications to the terahertz regime of the electromagnetic spectrum, with an emphasis on gain enhancement mechanisms. The numerical models of these antennas are presented and the analytical results are supported, using commercial simulators. The multilayer substrate microstrip transmission line at terahertz frequency is also explored and a method to obtain the various parameters of this interconnect at high frequency is described. This book will be a valuable resource for anyone needing to explore the terahertz band gap for future wireless communication, in an effort to solve the bandwidth (spectrum scarcity) problem.

Download or read book Nuclear Fusion written by and published by . This book was released on 2006 with total page 1102 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Reconfigurable Antennas written by Jennifer T. Bernhard and published by Morgan & Claypool Publishers. This book was released on 2007-12-01 with total page 74 pages. Available in PDF, EPUB and Kindle. Book excerpt: This lecture explores the emerging area of reconfigurable antennas from basic concepts that provide insight into fundamental design approaches to advanced techniques and examples that offer important new capabilities for next-generation applications. Antennas are necessary and critical components of communication and radar systems, but sometimes their inability to adjust to new operating scenarios can limit system performance. Making antennas reconfigurable so that their behavior can adapt with changing system requirements or environmental conditions can ameliorate or eliminate these restrictions and provide additional levels of functionality for any system. For example, reconfigurable antennas on portable wireless devices can help to improve a noisy connection or redirect transmitted power to conserve battery life. In large phased arrays, reconfigurable antennas could be used to provide additional capabilities that may result in wider instantaneous frequency bandwidths, more extensive scan volumes, and radiation patterns with more desirable side lobe distributions. Written for individuals with a range of experience, from those with only limited prior knowledge of antennas to those working in the field today, this lecture provides both theoretical foundations and practical considerations for those who want to learn more about this exciting subject. Contents: Introduction / Definitions of Critical Parameters for Antenna Operation / Linkage Between Frequency Response and Radiation Characteristics: Implications for Reconfigurable Antennas / Methods for Achieving Frequency Response Reconfigurability / Methods for Achieving Polarization Reconfigurability / Methods for Achieving Radiation Pattern Reconfigurability / Methods for Achieving Compound Reconfigurable Antennas / Practical Issues for Implementing Reconfigurable Antennas / Conclusions and Directions for Future work

Download or read book Antenna Handbook written by Y.T. Lo and published by Springer Science & Business Media. This book was released on 2013-06-29 with total page 2282 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.

Download or read book Analysis and Design of Transmitarray Antennas written by Ahmed H. Abdelrahman and published by Springer Nature. This book was released on 2022-06-01 with total page 151 pages. Available in PDF, EPUB and Kindle. Book excerpt: In recent years, transmitarray antennas have attracted growing interest with many antenna researchers. Transmitarrays combines both optical and antenna array theory, leading to a low profile design with high gain, high radiation efficiency, and versatile radiation performance for many wireless communication systems. In this book, comprehensive analysis, new methodologies, and novel designs of transmitarray antennas are presented. Detailed analysis for the design of planar space-fed array antennas is presented. The basics of aperture field distribution and the analysis of the array elements are described. The radiation performances (directivity and gain) are discussed using array theory approach, and the impacts of element phase errors are demonstrated. The performance of transmitarray design using multilayer frequency selective surfaces (M-FSS) approach is carefully studied, and the transmission phase limit which are generally independent from the selection of a specific element shape is revealed. The maximum transmission phase range is determined based on the number of layers, substrate permittivity, and the separations between layers. In order to reduce the transmitarray design complexity and cost, three different methods have been investigated. As a result, one design is performed using quad-layer cross-slot elements with no dielectric material and another using triple-layer spiral dipole elements. Both designs were fabricated and tested at X-Band for deep space communications. Furthermore, the radiation pattern characteristics were studied under different feed polarization conditions and oblique angles of incident field from the feed. New design methodologies are proposed to improve the bandwidth of transmitarray antennas through the control of the transmission phase range of the elements. These design techniques are validated through the fabrication and testing of two quad-layer transmitarray antennas at Ku-band. A single-feed quad-beam transmitarray antenna with 50 degrees elevation separation between the beams is investigated, designed, fabricated, and tested at Ku-band. In summary, various challenges in the analysis and design of transmitarray antennas are addressed in this book. New methodologies to improve the bandwidth of transmitarray antennas have been demonstrated. Several prototypes have been fabricated and tested, demonstrating the desirable features and potential new applications of transmitarray antennas.

Download or read book Advanced Radio Frequency Antennas for Modern Communication and Medical Systems written by Albert Sabban and published by BoD – Books on Demand. This book was released on 2020-09-23 with total page 282 pages. Available in PDF, EPUB and Kindle. Book excerpt: The main objective of this book is to present novel radio frequency (RF) antennas for 5G, IOT, and medical applications. The book is divided into four sections that present the main topics of radio frequency antennas. The rapid growth in development of cellular wireless communication systems over the last twenty years has resulted in most of world population owning smartphones, smart watches, I-pads, and other RF communication devices. Efficient compact wideband antennas are crucial in RF communication devices. This book presents information on planar antennas, cavity antennas, Vivaldi antennas, phased arrays, MIMO antennas, beamforming phased array reconfigurable Pabry-Perot cavity antennas, and time modulated linear array.

Download or read book Antenna Design for Cognitive Radio written by Youssef Tawk and published by Artech House. This book was released on 2016-06-30 with total page 289 pages. Available in PDF, EPUB and Kindle. Book excerpt: This one-of-a-kind new resource presents cognitive radio from an antenna design perspective and introduces the concept of cognitive radio as a protocol that benefits from under-utilized regions of the spectrum. This book covers topics that govern the operation of a cognitive radio and discusses the use of reconfigurable antennas, reconfigurable filtennas, and MIMO antennas for cognitive radio. The analysis and design of different antenna systems are presented, compared and evaluated. New approaches to improve spectrum efficiency are explored by demonstrating how to design software controlled cognitive radio antenna systems. This new resource shows how to communicate using either interweave or underlay cognitive radio and demonstrates the benefits of designing appropriate sensing and communicating antennas. The first part of the book introduces the basic concept of cognitive radio and discusses the difference between cognitive radio and software defined radio from the RF system 's perspective. The second part of the book discusses the main antenna design requirements, procedures and challenges for cognitive radio. The third part of the book introduces new trends in cognitive radio implementation such as the implementation of MIMO antennas on cognitive radio, the use of machine learning techniques to optimize the performance of a cognitive radio environment, and the implementation of cognitive radar and cognitive radio in space.

Download or read book Physics Briefs written by and published by . This book was released on 1994 with total page 1248 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Advanced Antenna Array Engineering for 6G and Beyond Wireless Communications written by Yingjie Jay Guo and published by John Wiley & Sons. This book was released on 2021-10-26 with total page 338 pages. Available in PDF, EPUB and Kindle. Book excerpt: Advanced Antenna Array Engineering for 6G and Beyond Wireless Communications Reviews advances in the design and deployment of antenna arrays for future generations of wireless communication systems, offering new solutions for the telecommunications industry Advanced Antenna Array Engineering for 6G and Beyond Wireless Communications addresses the challenges in designing and deploying antennas and antenna arrays which deliver 6G and beyond performance with high energy efficiency and possess the capability of being immune to interference caused by different systems mounted on the same platforms. This timely and authoritative volume presents innovative solutions for developing integrated communications networks of high-gain, individually-scannable, multi-beam antennas that are reconfigurable and conformable to all platforms, thus enabling the evolving integrated land, air and space communications networks. The text begins with an up-to-date discussion of the engineering issues facing future wireless communications systems, followed by a detailed discussion of different beamforming networks for multi-beam antennas. Subsequent chapters address problems of 4G/5G antenna collocation, discuss differentially-fed antenna arrays, explore conformal transmit arrays for airborne platforms, and present latest results on fixed frequency beam scanning leaky wave antennas as well as various analogue beam synthesizing strategies. Based primarily on the authors’ extensive work in the field, including original research never before published, this important new volume: Reviews multi-beam feed networks, array decoupling and de-scattering methods Provides a systematic study on differentially fed antenna arrays that are resistant to interference caused by future multifunctional/multi-generation systems Features previously unpublished material on conformal transmit arrays based on Huygen’s metasufaces and reconfigurable leaky wave antennas Includes novel algorithms for synthesizing and optimizing thinned massive arrays, conformal arrays, frequency invariant arrays, and other future arrays Advanced Antenna Array Engineering for 6G and Beyond Wireless Communications is an invaluable resource for antenna engineers and researchers, as well as graduate and senior undergraduate students in the field.