Download or read book Investigation of Cylindrically conformed Four arm Spiral Antennas written by Douglas J. Glass and published by . This book was released on 2007 with total page 167 pages. Available in PDF, EPUB and Kindle. Book excerpt: A four-arm spiral antenna offers broadband frequency response, wide beamwidths, reduced size compared to other antenna designs, and the ability to determine the relative direction of an incident signal with appropriate mode-forming. The reduced overall area projection of the four-arm spiral antenna compared to other antenna designs and the ability to be manufactured in a planar format allows the antenna to reside within an Unmanned Air Vehicle (UAV) fuselage. This thesis investigates the effects of cylindrically-conforming two different designs of a four-arm spiral antenna to reside within the fuselage of a medium-sized UAV. Theoretical predictions of antenna performance were created using the Numerical Electromagnetics Code (NEC) package and compared to measured results of flat and cylindrically-conformed four-arm spiral antennas with and without ground plane apertures.
Download or read book An Experimental Investigation of the Four arm Planar Logarithmic Spiral Antenna written by Preston Lee Ransom and published by . This book was released on 1965 with total page 142 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Four arm Spiral Antennas written by Robert G. Corzine and published by Artech House Antenna Library. This book was released on 1990 with total page 288 pages. Available in PDF, EPUB and Kindle. Book excerpt: Explains in detail the underlying principles of four-arm spiral direction-finding antennas for those who wish to design such systems. Includes performance results and practical aspects for the first-time designer. For all models, and for symmetrical and simplified variations, discusses mode forming,
Download or read book An Experimental Investigation of the Conical Four Arm Logarithmic Spiral Antenna with Large Cone Angle written by Ok Kyun Kim and published by . This book was released on 1966 with total page 122 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Radiation and Polarization Diversities of Compact Archimedean Spiral Antennas written by Ali Momen Mehrabani and published by . This book was released on 2014 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this thesis, four-arm Archimedean spiral antennas are investigated, which are low profile and have compact structure. The operating frequency bands can be designed for any microwave and millimeter frequency ranges and the antenna may be utilized in any desired applications such as Global Positioning Systems, radars, navigation systems, modern satellite communications, adaptive nulling, beam shaping, and direction finding. The concept of cavity backed absorber-filled structure along with a small ground plane embedded inside, as an inexpensive and wideband balun, is employed to reduce the axial size of the antenna. The antenna can generate broadside and boresight-null radiation patterns at the dominant and higher order modes, respectively. The study demonstrates that the proposed compact structure successfully supports the excitation of higher order modes. Polarization diversity of spiral antennas is mathematically described for an N-arm spiral antenna along with the required feeding networks. Realization of circularly-polarized broadside radiation patterns, with both senses of polarization, is then elaborated for a center-fed low-profile four-arm Archimedean spiral antenna. The radiation active zones, for generating both right- and left-handed circular polarization waves, are determined and the antenna performance in a frequency band, shared by both senses of polarization, is investigated. The developed antennas can be utilized in frequency reuse applications to enhance the wireless channel capacity and as primary feeds in high gain reflector antennas. Their performance in small front-fed parabolic reflector antennas is numerically investigated. It is shown that excellent circular polarization performance, with a remarkable radiation pattern symmetry and axial ratios below 0.5dB, low cross polarization components, and reflector total efficiencies, as high as 77.8% can be attained. Moreover, backward radiation properties of center-fed four-arm Archimedean spiral antennas are also explored, and their possible applications in reflector antennas are presented. Finally, the proposed dual-polarized spiral antennas are further investigated by dielectric loading, for size reduction purposes and frequency tuning applications. Both full and partial dielectric loadings are considered and investigated for the spiral antenna performance. A grooved dielectric substrate is also utilized to enable generating low-contrast dielectric permittivities. The spiral antenna performance, etched on such a grooved substrate, is similarly investigated.
Download or read book Technical Abstract Bulletin written by and published by . This book was released on with total page 828 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Investigation of Spiral Antennas written by Indhumathy Sathiaseelan and published by . This book was released on 2005 with total page 71 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Behavior of an Equiangular Spiral Antenna Placed Inside a Circular Cylindrical Waveguide written by I. David Woolf and published by . This book was released on 1962 with total page 32 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Frequency Independent Antennas written by Victor H. Rumsey and published by Academic Press. This book was released on 2014-06-28 with total page 161 pages. Available in PDF, EPUB and Kindle. Book excerpt: Frequency Independent Antennas provides a reasonably complete coverage of frequency independent antennas from its inception until the middle of 1965. Most of the contents have not previously been published, except in scattered journal articles, and some are original. The first six chapters are written at a fairly easy level—about the level of a beginning graduate student or the more advanced undergraduate. The last two chapters, which deal with solutions of Maxwell's equations, are at a somewhat higher level. The book opens with a discussion of some fundamental ideas about antennas. It shows how typical measurements can be understood in terms of classical electromagnetic theory: in other words, how to make sense of measured data, how to set up apparatus to get meaningful data, and how to test their significance. Separate chapters follow on the features of frequency independent, plane-sheet, spiral, and log-periodic antennas. Subsequent chapters discuss how the periodic structure theory provides a way of understanding the peculiarities of frequency independent antennas; and solutions of Maxwell's equations for idealized spiral and idealized sinusoidal structures.
Download or read book Helical and Spiral Antennas written by Hismatsu Nakano and published by Wiley. This book was released on 1988-01-12 with total page 284 pages. Available in PDF, EPUB and Kindle. Book excerpt: This monograph, the result of five years of research, presents a fully descriptive account of antennas and scatterers for a circularly polarized wave. The author presents the radiation characteristics of these antennas and scatterers with emphasis on their engineering aspects. Numerical examples treating a system consisting of wires and slots are described and thoroughly analyzed. The first chapter covers numerical methods and techniques for antenna analysis, followed by chapters describing the square spiral antenna, two-wire round spiral antenna, spiral antenna with two off-center sources, polarization diversity of Archimedian spiral antenna, helical antenna of endfire mode, helical antenna of backfire mode, conical helix antenna, and wire scatterer for a circularly polarized wave.
Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1989 with total page 1134 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Antennas written by Yi Huang and published by John Wiley & Sons. This book was released on 2008-09-15 with total page 378 pages. Available in PDF, EPUB and Kindle. Book excerpt: Practical, concise and complete reference for the basics of modern antenna design Antennas: from Theory to Practice discusses the basics of modern antenna design and theory. Developed specifically for engineers and designers who work with radio communications, radar and RF engineering, this book offers practical and hands-on treatment of antenna theory and techniques, and provides its readers the skills to analyse, design and measure various antennas. Key features: Provides thorough coverage on the basics of transmission lines, radio waves and propagation, and antenna analysis and design Discusses industrial standard design software tools, and antenna measurement equipment, facilities and techniques Covers electrically small antennas, mobile antennas, UWB antennas and new materials for antennas Also discusses reconfigurable antennas, RFID antennas, Wide-band and multi-band antennas, radar antennas, and MIMO antennas Design examples of various antennas are provided Written in a practical and concise manner by authors who are experts in antenna design, with experience from both academia and industry This book will be an invaluable resource for engineers and designers working in RF engineering, radar and radio communications, seeking a comprehensive and practical introduction to the basics of antenna design. The book can also be used as a textbook for advanced students entering a profession in this field.
Download or read book Methods of External Hyperthermic Heating written by Michel Gautherie and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 367 pages. Available in PDF, EPUB and Kindle. Book excerpt: The development of equipment capable of producing and monitoring safe, effective and predictable hyperthermia treatments represents a major challenge. The main problem associated with any heating technique is the need to adjust and control the distribution of absorbed power in the tissue during treatment. Power distribution is considered adequate only when tumor tissue can be maintained at the required hyperthermic levels while, at the same time, healthy tissue is not overheated. This problem is particularly crucial when external heating devices are used to produce hyperthermia. Ex ternal hyperthermia refers to those methods which supply heat to tumor tissue in an external, noninvasive manner, as opposed to internal hyperther mia by which heat is supplied to tumor tissue in situ. Until recently, most of the technical developments and clinical trials of ther motherapy for superficial and deep tumors have been based on elec tromagnetic systems. Presently, there is increasing interest in the use of ultra sound to accomplish these goals. Electromagnetic techniques of external thermotherapy include radiative, capacitive, and, to a lesser extent, inductive procedures. Recent designs for radiative applicators have incorporated microstrip structures. These have the advantage of being compact and lightweight compared with dielectrically loaded waveguide applicators.
Download or read book The Advancing World of Applied Electromagnetics written by Akhlesh Lakhtakia and published by Springer Nature. This book was released on with total page 825 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book 1999 IEEE AFRICON written by and published by . This book was released on 1999 with total page 726 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Protostars and Planets VI written by Henrik Beuther and published by University of Arizona Press. This book was released on 2014-12-18 with total page 945 pages. Available in PDF, EPUB and Kindle. Book excerpt: Proceedings of a conference held in Heidelberg, Germany, July 15-20, 2013.
Download or read book Broadband Planar Antennas written by Zhi Ning Chen and published by John Wiley & Sons. This book was released on 2006-05-01 with total page 258 pages. Available in PDF, EPUB and Kindle. Book excerpt: The increasing demand for wireless communications has revolutionised the lifestyle of today’s society and one of the key components of wireless technology is antenna design. Broadband planar antennas are the newest generation of antennas boasting the attractive features required, such as broad operating bandwidth, low profile, light weight, low cost and ease of integration into arrays or Radio Frequency (RF) circuits, to make them ideal components of modern communications systems. Research into small and broadband antennas has been spurred by the rapid development of portable wireless communication devices such as cell phones, laptops and personal digital assistants. This all-encompassing volume, Broadband Planar Antennas: Design and Applications, systematically describes the techniques for all planar antennas from microstrip patch antennas, suspended plate antennas and planar inverted-L/F antennas to planar dipole antennas. Also discussed are some of the most recent outcomes such as broadband antenna issues in promising ultra-wideband applications. Clearly describes the fundamentals of planar antennas and categorises them according to their radiation characteristics Introduces the advanced progress in broadband planar antennas for modern wireless communications Includes a wealth of case studies, design guidelines, figures and tables This text is essential reading for antenna, RF and microwave engineers and manufacturers within the telecommunications industry. Its highly accessible approach will also appeal to researchers, postgraduate students and academic lecturers.
