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 Characteristic Modes written by Yikai Chen and published by John Wiley & Sons. This book was released on 2015-05-19 with total page 294 pages. Available in PDF, EPUB and Kindle. Book excerpt: Describes how to systematically implement various characteristic mode (CM) theories into designs of practical antenna systems This book examines both theoretical developments of characteristic modes (CMs) and practical developments of CM-based methodologies for a variety of critical antenna designs. The book is divided into six chapters. Chapter 1 provides an introduction and discusses the recent advances of the CM theory and its applications in antenna engineering. Chapter 2 describes the formulation of the characteristic mode theory for perfectly electrically conducting (PEC) bodies and discusses its numerical implementations. Chapter 3 presents the CM theory for PEC structures embedded in multilayered medium and its applications. Chapter 4 covers recent advances in CM theory for dielectric bodies and also their applications. Chapter 5 discusses the CM theory for N-port networks and its applications to the design of antenna arrays. Finally, Chapter 6 discusses the design of platform-integrated antenna systems using characteristic modes. This book features the following: Introduces characteristic mode theories for various electromagnetic structures including PEC bodies, structures in multilayered medium, dielectric bodies, and N-port networks Examines CM applications in electrically small antennas, microstrip patch antennas, dielectric resonator antennas, multiport antennas, antenna arrays, and platform mounted antenna systems Discusses numerical algorithms for the implementation of the characteristic mode theories in computer code Characteristic Modes: Theory and Applications in Antenna Engineering will help antenna researchers, engineers, and students find new solutions for their antenna design challenges.

Download or read book Design and Location Optimization of Electrically Small Antennas Using Modal Techniques written by Jeffrey Michael Chalas and published by . This book was released on 2015 with total page 107 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this dissertation, the Theory of Characteristic Modes is used as a framework for the design, optimization, and benchmarking of electrically small radiating systems. The foundation of this work is in the theory of Characteristic Modes, an eigenvalue equation of the Method of Moments impedance matrix [Z], that leads to derive the fundamental radiation modes of arbitrary-shaped bodies. After an overview of small antenna theory, we derive a new method for computing the Q factor of arbitrary-shaped radiating bodies using CMs using only the Method of Moments impedance matrix [Z]. Following this derivation, we present a new method for computing the fundamental limits on Q (and thus bandwidth) for arbitrary-shaped antennas. As a by-product of this method, we extract the optimal current distribution as a function of antenna shape for design guidelines. We further extend this theory to find the Q limits of arbitrary-shaped antennas and antenna-platform systems, subject to specific radiation pattern requirements. In the second part of the thesis, we use the Theory of Characteristic Modes to optimize the location and excitation of single and multiple in-situ ESAs mounted on finite, sub-wavelength platforms as relates to unmanned aerial vehicles (UAVs). By properly analyzing the CMs of the supporting platform, we show that a complex, multivariate optimization problems can by radically simplified using CMs. Based on this capability, we present a new, systematic design methodology for location optimization of small antennas on-board finite platforms. The approach is shown to drastically reduce the time, computational cost, and complexity of a multi-element in-situ antenna design, as well as providing significant performance improvements in comparison to a typical single-antenna implementations.

Download or read book Small Antennas Miniaturization Techniques Applications written by John Volakis and published by McGraw Hill Professional. This book was released on 2009-12-22 with total page 449 pages. Available in PDF, EPUB and Kindle. Book excerpt: Next-generation small antenna design techniques This authoritative text provides the most up-to-date methods on the theory and design of small antennas, including an extensive survey of small antenna literature published over the past several years. Written by experts at the forefront of antenna research, Small Antennas: Miniaturization Techniques & Applications begins with a detailed presentation of small antenna theory--narrowband and wideband--and progresses to small antenna design methods, such as materials and shaping approaches for multiband and wideband antennas. Generic miniaturization techniques are presented for narrowband, multiband, and wideband antennas. Two chapters devoted to metamaterials antennas and methods to achieve optimal small antennas, as well as a chapter on RFID technologies and related antennas, are included in this comprehensive volume. Coverage includes: Small antenna theory and optimal parameters Theory and limits of wideband electrically small antennas Extensive literature survey of small antenna designs Practical antenna miniaturization approaches Conformal wideband antennas based on spirals Negative refractive index (NRI) metamaterial and electromagnetic band gap (EBG) based antennas Small antennas based on magnetic photonic and degenerate band edge crystals Impedance matching for small antennas using passive and active circuits RFID antennas and technology

Download or read book Characteristic Modes for Impedance Matching and Broadbanding of Electrically Small Antennas written by Jacob J. Adams and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Antennas smaller than a quarter wavelength are fundamentally constrained in a variety of ways. One of the more problematic limitations is that the antenna's bandwidth declines sharply as the size of the antenna decreases. Myriad studies have sought antennas that perform close to the fundamental limits, and they use a patchwork of good and bad design approaches. Our primary goal is to describe a new, complete framework to model the fundamental behavior of small antennas. We base our analysis in characteristic mode theory which allows us to decompose the antenna behavior into the behavior of a few well-defined modes. Using this decomposition we can better understand, design, and analyze small antennas. First, we explain a unified approach to model the antenna input impedance, rather than the haphazard array of approaches that are currently used. Using our model for the input impedance, we are then able to establish the conditions under which a small antenna can be effectively impedance matched, and analyze some simple methods for matching an antenna without using an external matching network. Through this study, we find that near-optimum modes actually exist in nearly every geometry but are often masked by higher order modes. From this result, a new design paradigm is proposed in which designs seek to couple into these existing modes and match using the simple methods described herein, rather than creating ever more complex and impractical structures. We also design and fabricate two novel, spherical, electrically small antennas, the TM10 antenna and the spherical meanderline antenna. Both of these antennas exhibit quality factor close to the lower limit, and hence, a near-optimum bandwidth. The spherical meanderline antenna is particularly well-suited for automated fabrication and can achieve bandwidth comparable to the best known values. In collaboration with materials scientists, we demonstrate the spherical meanderline antenna, which is one of the first microwave structures printed on a curved surface using a direct-ink write process. Finally, to circumvent some of the bandwidth limitations imposed on small antennas, we propose an approach to design multimode antennas. Estimates are derived for the bandwidth increases that can be achieved with this approach to antenna broadbanding, and a simple figure of merit is suggested. A case study in broadbanding the TM10 antenna provides some idea of what types of modal combinations are practical. Finally, a multimode spherical meanderline antenna matched with the simple techniques described herein is designed and fabricated.

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 Antenna Shape Synthesis Using Characteristic Mode Concepts written by Jonathan L. T. Ethier and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Characteristic modes (CMs) provide deep insight into the electromagnetic behaviour of any arbitrarily shaped conducting structure because the CMs are unique to the geometry of the object. We exploit this very fact by predicting a perhaps surprising number of important antenna metrics such as resonance frequency, radiation efficiency and antenna Q (bandwidth) without needing to specify a feeding location. In doing so, it is possible to define a collection of objective functions that can be used in an optimizer to shape-synthesize antennas without needing to define a feed location a priori. We denote this novel form of optimization "feedless" or "excitation-free" antenna shape synthesis. Fundamentally, we are allowing the electromagnetics to dictate how the antenna synthesis should proceed and are in no way imposing the physical constraints enforced by fixed feeding structures. This optimization technique is broadly applied to three major areas of antenna research: electrically small antennas, multi-band antennas and reflectarrays. Thus, the scope of applicability ranges from small antennas, to intermediate sizes and concludes with electrically large antenna designs, which is a testament to the broad applicability of characteristic mode theory. Another advantage of feedless electromagnetic shape synthesis is the ability to synthesize antennas whose desirable properties approach the fundamental limits imposed by electromagnetics. As an additional benefit, the feedless optimization technique is shown to have greater computational efficiency than traditional antenna optimization techniques.

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 Ultra Wideband Antennas written by Giselle M. Galvan-Tejada and published by CRC Press. This book was released on 2017-12-19 with total page 285 pages. Available in PDF, EPUB and Kindle. Book excerpt: Ultra Wideband Antennas: Design, Methodologies, and Performance presents the current state of the art of ultra wideband (UWB) antennas, from theory specific for these radiators to guidelines for the design of omnidirectional and directional UWB antennas. Offering a comprehensive overview of the latest UWB antenna research and development, this book: Discusses the developed theory for UWB antennas in frequency and time domains Delivers a brief exposition of numerical methods for electromagnetics oriented to antennas Describes solid-planar equivalence, which allows flat structures to be implemented instead of volumetric antennas Examines the impedance matching, phase linearity, and radiation patterns as design objectives for omnidirectional and directional antennas Addresses the time domain signal analysis for UWB antennas, from which the distortion phenomenon can be modeled Includes illustrative examples, design equations, CST MICROWAVE STUDIO® simulations, and MATLAB® plot generations Compares the performance of different UWB antennas, supplying useful insight into particular tendencies and unresolved problems Ultra Wideband Antennas: Design, Methodologies, and Performance provides a valuable reference for the scientific community, as UWB antennas have a variety of applications in body area networks, radar, imaging, spectrum monitoring, electronic warfare, wireless sensor networks, and more.

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 Wideband Electrically Small Antennas written by Charles Edward Ryan and published by . This book was released on 1975 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Pattern Reconfigurable Printed Antennas and Time Domain Method of Characteristic Modes for Antenna Analysis and Design written by Nuttawit Surittikul and published by . This book was released on 2006 with total page 164 pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: The work considered here discusses two related topics. First, the development of a novel pattern reconfigurable printed antenna element for Global Positioning System (GPS) applications is presented. This antenna element consists of a microstrip patch, fed by four probes, and surrounded by a parasitic octagonal metallic ring loaded with diode switches. The patch and ring are located on top of a thick dielectric substrate. This novel concept is based on controlling the propagation characteristics of surfaces waves within the substrate by using a metallic parasitic ring. If properly designed, this ring can control the radiated surface waves that interact with the main beam radiated by the patch itself. It is shown through computer simulations and measurements that the beamwidth of the antenna can be changed by turning the diode switches on and off. This dissertation discusses the complete design of the radiating patch, diode switches and biasing circuitry. The effect of these additional structures on the radiation pattern is also discussed since our computer models do include these components. This antenna concept was developed to minimize the effect of interfering signals incident on the antenna along the horizon. This dissertation also shows that microstrip antennas can be fabricated with a thick substrate without the usual surface wave problem. The second topic considered in this dissertation is the development of the theory of characteristic modes using a time domain Maxwell equations solver. This method can provide a clear physical insight to the behavior of antennas. The conventional approach for computing the characteristic modes has been in the frequency domain in conjunction with the Method of Moments. The method described here uses the finite difference time domain (FDTD) technique. The proposed method provides a major advantage over previous frequency domain algorithms because the resonances of the structure can be captured in a single FDTD run. To illustrate the method, we compute the resonances as well as the characteristic modes for several structures, such as, a printed dipole antenna, a reconfigurable printed antenna for application in the global positioning system (GPS) and a log-periodic antenna which is a wideband structure. To access the validation of our proposed method, we compare the simulated results to the analytical solutions, and discover an excellent agreement between the resonances predicted by both methods.

Download or read book Ultra Wideband Antennas and Propagation written by Ben Allen and published by Wiley. This book was released on 2006-11-10 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Providing up-to-date material for UWB antennas and propagation as used in a wide variety of applications, "Ultra-wideband Antennas and Propagation for Communications, Radar and Imaging" includes fundamental theory, practical design information and extensive discussion of UWB applications from biomedical imaging, through to radar and wireless communications. An in-depth treatment of ultra-wideband signals in practical environments is given, including interference, coexistence and diversity considerations. The text includes antennas and propagation in biological media in addition to more conventional environments. The topics covered are approached with the aim of helping practising engineers to view the subject from a different angle, and to consider items as variables that were treated as constants in narrowband and wideband systems. Features tables of propagation data, photographs of antenna systems and graphs of results (e.g. radiation patterns, propagation characteristics) Covers the fundamentals of antennas and propagation, as well as offering an in-depth treatment of antenna elements and arrays for UWB systems, and UWB propagation models Provides a description of the underlying concepts for the design of antennas and arrays for conventional as well as ultra-wideband systems Draws together UWB theory by using case-studies to show applications of antennas and propagation in communication, radar and imaging systems The book highlights the unique design issues of using ultra-wideband and will serve both as an introductory text and a reference guide for designers and students alike.

Download or read book Bandwidth Enhancement and Miniaturization Techniques for Small Antennas written by Ting-Yen Shih and published by . This book was released on 2017 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The HF/VHF frequency bands (3-300 MHz) are used by various long-range wireless communication systems in both military and commercial applications. Due to the large wavelengths in these bands, the antennas used in such applications are often electrically-small. While wide bandwidth is desired for high data rates, the electrically-small antennas (ESAs) tend to have very small bandwidth since there is a trade-off between small antenna size and wide bandwidth. For each ESA, the upper bound of its bandwidth can be calculated. Despite the fact that fundamental limitations restrain the performance of small antennas, the growing need of compact and broadband wireless devices for communication and sensor systems has tremendously stimulated the demand for small antennas with performance levels approaching, or even exceeding, these limitations. To address this need, I pursue novel bandwidth enhancement and miniaturization techniques for small antennas. In this dissertation, three parallel approaches that I took to investigate bandwidth enhancement and miniaturization techniques for small antennas are presented. The first method employs a novel loading structure to allow antennas to achieve compact and miniaturized dimensions while maintaining a wide bandwidth. The second method involves utilizing the presence of metallic objects that are in the vicinity of the ESAs-more specifically, the platforms (e.g. vehicles, airplanes) on which the ESAs are mounted. In this method, the platforms are considered as the main radiators, and the ESAs act mainly as coupling elements. The third method is to design highly-efficient active non-Foster matching circuits to bypass the gain-bandwidth limitations of the ESAs and achieve wide impedance bandwidth. All three methods have been experimentally validated.

Download or read book Achieving Wide Bandwidth Electrically Small Antennas Using Internal Non Foster Elements written by Ryan Thomas Cutshall and published by . This book was released on 2013 with total page 116 pages. Available in PDF, EPUB and Kindle. Book excerpt: Electromagnetic equations pertaining to electrically small dipole antennas and electrically small monopole antennas with small circular ground planes are reviewed. Two electrically small antenna designs are analyzed numerically and the results are compared. The first is a frequency agile version of the two-dimensional (2D) planar Egyptian axe dipole (EAD) antenna. The second is its three-dimensional (3D) counterpart. The frequency agile performance characteristics of both the 2D and 3D EAD designs are studied and compared. The potential for non-Foster augmentation to achieve large instantaneous fractional impedance bandwidths is detailed for each antenna. In addition, details are given on how to run frequency agile simulations in both ANSYS HFSS and Agilent's ADS. Details are also provided on how to generate an antenna's non-Foster.

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 Designing Electrically Small Antennas and the Effects of Their Radiation on Humans written by Abu Taher Mohammad Sayem and published by . This book was released on 2007 with total page 260 pages. Available in PDF, EPUB and Kindle. Book excerpt: