Download or read book Analysis and Design of Electrically Small Antennas for Non line of sight Communications written by Sungkyun Lim and published by . This book was released on 2007 with total page 252 pages. Available in PDF, EPUB and Kindle. Book excerpt: As the demand for compact, portable communication electronics increases, the technology of miniaturization has made great progress. A beneficiary of that progress has been research into new concepts for the antenna, one of the essential components in wireless communications. As the size of an antenna becomes smaller, however, the antenna suffers from high Q and low radiation resistance. The results are narrow bandwidth, poor matching, low efficiency, and, more generally, poor performance throughout the communication system. First, the design of a small antenna for HF/VHF communications is described. As the operating frequency of an antenna decreases, for example, into the HF and low VHF regions, the physical size of the antenna becomes a critical issue. It is desirable to design a truly electrically small antenna by reducing the ground plane size. Moreover, when the antenna size is very small, the bandwidth of the antenna is extremely narrow, which is critical to various deployment variances and propagation effects such as multi-path fading. The new design, which is an inductively coupled, top-loaded, monopole structure optimized by a genetic algorithm (GA), maximizes transmission of HF/VHF waves. Electrically small, spiral ground planes for the monopole and the electrically small antenna are designed for HF ground-wave transmission. In addition, a tunable small antenna is investigated that overcomes the narrow-bandwidth limitation of electrically small antennas. Second, new design methodologies for electrically small antennas are discussed. Use of an inductively coupled feed is one of the well-known methods for boosting input resistance. As the antenna size becomes smaller, however, it is found that the efficiency of an antenna using an inductively coupled feed is lower than an antenna using multiple folds. After a comparison of the two methods, the design of a thin, multiply folded, electrically small antenna is proposed for achieving high efficiency in a physically compact size. The GA is used to assess the effect of geometry on the performance (in terms of efficiency and bandwidth) of the electrically small antennas, including the folded conical helix and folded spherical helix. Finally, the prospects of using the new Yagi antennas to achieve small size are explored. Yagi antennas are used widely to obtain high gain in a simple structures. The antenna is composed of the driven element and the parasitic elements, which include a reflector and one or more directors. Typically, sufficient spacing on the order of 0.15[lambda] to 0.4[lambda] between the driven element and the parasitic elements is needed for the Yagi antenna to operate well. For some applications, however, it is desirable to reduce the spacing and the length of the elements to achieve a physically more compact size. In this dissertation, closely spaced, folded Yagi antennas in both three dimensions and two dimensions are investigated, and a design for an electrically small Yagi antenna is suggested.

Download or read book Small Antenna Handbook written by Robert C. Hansen and published by John Wiley & Sons. This book was released on 2011-08-26 with total page 362 pages. Available in PDF, EPUB and Kindle. Book excerpt: Now in an completely revised, updated, and enlarged Second Edition, Small Antennas in Portable Devices reviews recent significant theoretical and practical developments in the electrically small antenna area. Examining antenna designs that work as well as those that have limitations, this new edition provides practicing engineers and upper level and graduate students with new information on: work on improving bandwidth using spherical helix dipoles; work on electromagnetically coupled structures; exact derivation of the Q for electrically small antennas for both the TE and TM modes; and a new simplified Q formula.

Download or read book Analysis of Electrically Small Antenna Designs and Limitations written by James C. Howell and published by . This book was released on 2018 with total page 70 pages. Available in PDF, EPUB and Kindle. Book excerpt: Author's abstract: Electronic sizes are constantly decreasing. The need for smaller communication systems is at an all-time high. The antenna is a major part of wireless communication systems, so the need for smaller antennas is also paramount. Electrically-small antennas are the solution to this problem. Electrically-small antennas have many inherent limitations. In this thesis, a comprehensive background on electrically-small antennas is conducted to illustrate the common design limitations that face electrically-small antennas. Three novel, size-reduced antennas are presented in this thesis. A 15-element size-reduced Yagi-Uda antenna, a 6-element size-reduced antenna, and a spherical helix electrically-small antenna are all introduced in this thesis. The antennas are all designed, simulated, fabricated, and measured for verification of results.

Download or read book Modern Small Antennas written by Kyohei Fujimoto and published by Cambridge University Press. This book was released on 2014-01-09 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: If you are involved in designing and developing small antennas, this complete cutting-edge guide covers everything you need to know. From fundamentals and basic theory to design optimization, evaluation, measurements and simulation techniques, all the essential information is included. You will also get many practical examples from a range of wireless systems, whilst a glossary is provided to bring you up to speed on the latest terminology. A wide variety of small antennas is covered, and design and practice steps are described for each type: electrically small, functionally small, physically constrained small and physically small. Whether you are a professional in industry, a researcher, or a graduate student, this is your essential guide to small antennas.

Download or read book Small Antenna Design written by Douglas B. Miron and published by Elsevier. This book was released on 2006-03-22 with total page 304 pages. Available in PDF, EPUB and Kindle. Book excerpt: As wireless devices and systems get both smaller and more ubiquitous, the demand for effective but small antennas is rapidly increasing. Small Antenna Design describes the theory behind effective small antenna design and give design techniques and examples for small antennas for different operating frequencies. Design techniques are given for the entire radio spectrum, from a very hundred kilohertz to the gigahertz range. Unlike other antenna books which are heavily mathematical and theoretical, Douglas Miron keeps mathematics to the absolute minimum required to explain design techniques. Ground planes, essential for operation of many antenna designs, are extensively discussed. Author's extensive experience as a practicing antenna design engineer gives book a strong "hands-on" emphasis Covers antenna design techniques from very low frequency (below 300 kHz) to microwave (above 1 GHz) ranges Special attention is given to antenna design for mobile/portable applications such as cell phones, WiFi, etc

Download or read book Antennas for Small Mobile Terminals written by Kyohei Fujimoto and published by Artech House. This book was released on 2018-09-30 with total page 340 pages. Available in PDF, EPUB and Kindle. Book excerpt: With the progress and rapid increase in mobile terminals, the design of antennas for these small systems is becoming more and more important. This forward-looking volume offers professionals current and comprehensive coverage of the design, development, and implementation of small, compact, and lightweight antennas in mobile communication terminals. The book discusses a wide range of communication systems, from Radio-frequency identification (RFID), and near field communications (NFC), to wireless power transmission (WPT) and broadband wireless networks. Engineers learn how to use small antennas in mobile phones, wearable systems, laptop computers, radio watches, and broadband wireless networks such as WLAN and WiMAX. This definite reference covers the critical applications today’s professionals need to understand, from antennas for IoT and antenna design for 5G mm-wave devices, to body-centric communication systems and antennas for unmanned aerial vehicles.

Download or read book Design Methodology for Wideband Electrically Small Antennas ESA Based on the Theory of Characteristic Modes CM written by Khaled A. Obeidat and published by . This book was released on 2010 with total page 104 pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: Emerging broadband applications with market pressures for miniaturized communication devices have encouraged the use of electrically small antennas (ESA) and highly integrated RF circuitry for high volume low cost mobile devices. This research work focuses on developing a novel scheme to design wideband electrical small antennas that incorporates active and passive loading as well as passive matching networks. Several antennas designed using the proposed design technique and built and measured to assess their performance and to validate the design methodology. Previously, the theory of Characteristic Modes (CM) has been used mostly for antennas analysis. However; in this chapter a design procedure is proposed for designing wide band (both the input impedance bandwidth and the far field pattern bandwidth) electrically small to mid size antennas using the CM in conjunction with the theory of matching networks developed by Carlin. In order to increase the antenna gain, the antenna input impedance mismatch loss needs to be minimized by carefully exciting the antenna either at one port or at multiple ports and/or load the antenna at different ports along the antenna body such that the Q factor in the desired frequency range is suitable for wideband matching network design. The excitation (feeding structure), the loading of the antenna and/or even small modifications to the antenna structure can be modeled and understood by studying the eigenvalues and their corresponding eigencurrents obtained from the CM of the antenna structure. A brief discussion of the theory of Characteristic Modes (CM) will be presented and reviewed before the proposed design scheme is introduced. The design method will be used to demonstrate CM applications to widen the frequency bandwidth of the input impedance of an electrically small Vee shape Antenna and to obtain vertically polarized Omni-directional patterns for such antenna over a wide bandwidth. A loading technique based on the CM to either design frequency reconfigurable antennas or broaden their bandwidth by Non-Foster loading will also be discussed as part of the design methodology. In the Appendix, a brief discussion of the fundamental limits of electrical small antennas is presented and then followed by a discussion of the fundamental limits of the impedance bandwidth of the ESA when a passive matching network is used. Matching network implemented using Non-Foster matching is also discussed in the appendix.

Download or read book The Design and Analysis of Electrically Small Antennas Utilizing Top Loading for Optimized Wireless Communications written by Joseph Meador and published by . This book was released on 2016 with total page 72 pages. Available in PDF, EPUB and Kindle. Book excerpt: Author's abstract: With the advancement, availability, and the convenience of wireless technologies wireless networks are becoming common practice for households and companies. There is an inherent need to maintain these wireless networks secure because of personal or sensitive material that is transmitted over wireless mediums. Novel antenna designs that reduce the antenna size allow for uses in both the medical and cybersecurity domains. A wireless security zone can be created if directional wide beamwidth antennas are placed in an outward facing manner transmitting noise, then the area inside the outward facing antennas will be secure due to the fact that any intruder would only be able to detect the noise or false data. Continued security improvements can be made by controlling the internal network coverage area with directional antennas and variable use of transmitted power. The results are conclusive with the testing that has been done to ensure a secure wireless network.

Download or read book Electrically Small Superdirective and Superconducting Antennas written by R. C. Hansen and published by John Wiley & Sons. This book was released on 2006-06-19 with total page 168 pages. Available in PDF, EPUB and Kindle. Book excerpt: A seminal reference to electrically small antennas for today's wireless and Wi-Fi world This book is dedicated to the challenges posed by electrically small antennas and their solutions. Electrically small antennas have characteristics that limit performance: low radiation resistance, high reactance, low efficiency, narrow bandwidth, and increased loss in the matching network. Most of these limitations are shared by two other classes of antennas: superdirective and superconducting antennas. All three classes of antennas are thoroughly treated in three interrelated parts: * Part One, Electrically Small Antennas, begins with a discussion of the fundamental limitations of bandwidth and matching, then provides detailed design information on loaded whips and dipoles, ferrite loops, patches with unusual substrates, and dielectric resonator antennas. In addition to exploring designs that work, the author sets forth antenna designs that are based on good physics yet are poor performers, as well as designs with both poor underlying physics and poor performance. * Part Two, Superdirective Antennas, sets forth basic capabilities and limitations of superdirective antennas, both apertures and arrays, and investigates bandwidth, efficiency, and tolerances. The author explores the magnification of intrinsic matching circuit loss due to a large mismatch and evaluates the recent and promising non-Foster matching circuits. * Part Three, Superconducting Antennas, reviews superconductivity concepts and new principles for dipole, loop, and patch antennas. The author concludes with a discussion of superconducting delay lines for wideband phased array steering. Throughout the book, the author provides readers with a historical perspective, setting forth what has been investigated, what works, and what does not. Each part has its own author index and a list of references to help readers continue their explorations of particular topics.With the explosive demand for wireless and Wi-Fi, this seminal reference is essential reading for all antenna professionals and is recommended as a graduate-level course book.

Download or read book Compact Antennas for Wireless Communications and Terminals written by Jean-Marc Laheurte and published by John Wiley & Sons. This book was released on 2012-12-27 with total page 264 pages. Available in PDF, EPUB and Kindle. Book excerpt: Compact Antennas for Wireless Communications and Terminals deals with compact microwave antennas and, more specifically, with the planar version of these antennas. Planar antennas are the most appropriate type of antenna in modern communication systems and more generally in all applications requiring miniaturization, integration and conformation such as in mobile phone handsets. The book is suitable for students, engineers and scientists eager to understand the principles of planar and small antennas, their design and fabrication issues, and modern aspects such as UWB antennas, reconfigurable antennas and diversity issues.

Download or read book The Design and Analysis of Planar Electrically Small Antennas written by Yanyan Zhang and published by . This book was released on 2010 with total page 256 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Design and Analysis of Circularly Polarized Electrically Small Antennas written by Jesse R. Ludwig and published by . This book was released on 2008 with total page 72 pages. Available in PDF, EPUB and Kindle. Book excerpt: Author's abstract: A growing need for efficient wireless communication is prevalent in the world in which we live. From cell phones to television to GPS applications, wireless communications are vital in consumer electronics and military applications. In these applications, a miniaturized antenna is sometimes necessary for reducing overall size of the communication system. For many satellite based communication applications, circular polarization in antennas is needed for efficient communication. In this thesis, the miniaturization technique known as T-top loading is utilized on two novel antenna designs. One design is an electrically small, circularly polarized planar cross dipole and the other design is a compact circularly polarized log-periodic dipole array. Both antennas are designed in simulation software with the intent for prototype fabrication for measurement verification of simulation results.

Download or read book The Shape Synthesis of Non Planar and Closely Spaced Electrically Small Conducting Surface Antennas written by Anas Alakhras and published by . This book was released on 2020 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Antennas are needed in wireless communications of any kind and are key to the quality of any wireless link, irrespective of its use. There remains a need for electrically-small antennas that can fit on/in a restricted physical surface/volume for use in sensors (eg. Internet-of-Things) that need to "talk" to some data centre via the wireless network. The design issues associated with electrically-small antennas are well-known, and thus it will be appreciated that it would be advantageous to be able to design the above antennas in a way that exploits as much of the space allotted to them, as well the proximity of other objects present, to arrive at functioning antennas. Antennas of conventional shape do not necessarily do this. It might thus be best to perform a shape synthesis of an antenna that lets the electromagnetics decide on the shape of the final antenna in order to obtain the performance desired under the geometrical restrictions mentioned. Such shape synthesis has only been done for planar (2D) conducting surface antennas. In this thesis we develop the machinery for a computational electromagnetics-based tool capable of performing the shape synthesis of 3D conducting surface antennas for the first time. It has purposefully been developed in a way that allows it to capitalize on commercially available software for both the computational electromagnetics (CEM) and the genetic optimization algorithm (GA). A comprehensive 'shaping manager' software tool has been developed that controls the whole shaping process and communicates with the commercial software, in so doing implementing a desired shaping prescription. It is a complex tool whose development is based on a considerable amount of software engineering. The advantage of being able to utilize the commercial codes is that the work becomes accessible to others, such codes are more powerful and flexible than in-house codes, and they are also able to export files describing the complicated shaped geometries for fabrication. The shaping manager utilizes the characteristic mode concept so that one only needs to select the feed point once the shape synthesis has been completed. Fully 3D electrically-small conducting surface antenna examples are then successfully shape synthesized subject to various geometry restrictions. The validity of the modelling process is experimentally validated. The shape synthesis procedure is then extended to apply to the design of two closely-spaced electrically-small antennas operating at different frequencies, again with some experimental validation. Such shape synthesis has also not been done before. These procedures can be extended to the case where the two antennas in question are mounted on some electrically-large platform. However, if such platforms are electrically very large the full-wave computational burden may become prohibitive. We show that the characteristic modes for the antennas under shaping in such situations can in fact be found using hybrid method of moment / geometrical theory of diffraction (MM/GTD) methods, with only the antenna proper needing to be MM-meshed. An example is provided to demonstrate the computation of characteristic modes in this way. This possibility for characteristic mode computation has not yet been explicitly stated elsewhere (and so perhaps not realised), nor example computations provided. We believe this realisation might widen the scope of application of characteristic mode analysis.

Download or read book Theoretical and Numerical Analysis of a Novel Electrically Small and Directive Antenna written by Jeffrey Elloian and published by . This book was released on 2014 with total page 272 pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: Small antennas have attracted significant attention due to their prolific use in consumer electronics. Such antennas are highly desirable in the healthcare industry for imaging and implants. However, most small antennas are not highly directive and are detuned when in the presence of a dielectric. The human body can be compared to a series of lossy dielectric media. A novel antenna design, the orthogonal coil, is proposed to counter both of these shortcomings. As loop antennas radiate primarily in the magnetic field, their far field pattern is less influenced by nearby lossy dielectrics. By exciting two orthogonal coil antennas in quadrature, their beams in the H-plane constructively add in one direction and cancel in the other. The result is a small, yet directive antenna, when placed near a dielectric interface. In addition to present a review of the current literature relating to small antennas and dipoles near lossy interfaces, the far field of the orthogonal coil antenna is derived. The directivity is then plotted for various conditions to observe the effect of changing dielectric constants, separation from the interface, etc. Numeric simulations were performed using both Finite Difference Time Domain (FDTD) in MATLAB and Finite Element Method (FEM) in Ansys HFSS using a anatomically accurate high-fidelity head mesh that was generated from the Visible Human Project® data. The following problem has been addressed: find the best radio-frequency path through the brain for a given receiver position -- on the top of the sinus cavity. Two parameters: transmitter position and radiating frequency should be optimized simultaneously such that (i) the propagation path through the brain is the longest; and (ii) the received power is maximized. To solve this problem, we have performed a systematic and comprehensive study of the electromagnetic fields excited in the head by the aforementioned orthogonal dipoles. Similar analyses were performed using pulses to detect Alzheimer's disease, and on the femur to detect osteoporosis.

Download or read book Design Fabrication and Characterization of a Dual band Electrically Small Antenna ESA for Wireless Communications written by Chin Chieh Hsu and published by . This book was released on 2012 with total page 192 pages. Available in PDF, EPUB and Kindle. Book excerpt: "A printed dual-band meander-line monopole antenna that operates in frequency range of 2.4-2.48, 5.15-5.35, and 5.725-5.825 GHz was designed, fabricated, and characterized"--Leaf iv.

Download or read book Novel Electrically Small Antennas and Metamaterial High Impedance Surfaces written by and published by . This book was released on 2005 with total page 49 pages. Available in PDF, EPUB and Kindle. Book excerpt: This final report presents a summary of the work performed on the project "Novel Electrically Small Antennas and Metamaterial High Impedance Surfaces," under ONR Grant No. N00014-04-1-0619, over the period of June 1, 2004 to September 30, 2005. The main accomplishments are: 1. Investigation of fundamental characteristics of matched off-center fed Space-Filling Curve (SF-Curve) radiating elements such as Hilbert curve and Peano curve antennas for low-frequency applications, and fabrication and measurement of a prototype to verify the theory. 2. Analysis of mutual coupling effects between a pair of SF-curve antennas, and investigation of Yagi arrays made of Peano or Hilbert antenna elements. 3. Analysis of high-impedance surfaces (ground-planes), also known as artificial magnetic conductors (AMC), made of a periodic arrangement of inclusions made of Hilbert or Peano scattering elements, fabrication and measurement of a Hilbert AMC surface. 4. Application of SF-curve AMC surfaces in design of electrically thin microwave absorbers for RCS reduction, and analysis and RCS measurement of a rectangular conducting plate covered by such a surface to confirm the theory. 5. Application of an array made of SF-curve resonating elements in design of novel RFID tags, and their performance analysis in RF tagging of dielectric and conducting cylindrical objects.

Download or read book Wideband Multiband and Smart Reconfigurable Antennas for Modern Wireless Communications written by Matin, Mohammad A. and published by IGI Global. This book was released on 2015-08-26 with total page 440 pages. Available in PDF, EPUB and Kindle. Book excerpt: Modern society thrives on communication that is instant and available at all times, a constant exchange of information that encompasses everything from video streaming to GPS navigation. Experts even suggest that in the near future everything from our cars to our kitchen appliances will be connected to the internet, a feat that would not be possible without advanced wireless technology. Wideband, Multiband, and Smart Reconfigurable Antennas for Modern Wireless Communications showcases current trends and novel approaches in the design and analysis of the antennas that make wireless applications possible, while also identifying unique integration opportunities for antennas and wireless applications to work together. By featuring both theoretical and experimental approaches to integration, this book highlights specific design issues to assist a wide-range of readers including students, researchers, academics, and industry practitioners. This publication features chapters on a broad scope of topics including algorithms and antenna optimization, wireless infrastructure development, wireless applications of intelligent algorithms, antenna architecture, and antenna reconfiguration techniques.