Design And Location Optimization Of Electrically Small Antennas Using Modal Techniques
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| Author | : Jeffrey Michael Chalas |
| Publisher | : |
| Total Pages | : 107 |
| Release | : 2015 |
| Genre | : |
| ISBN | : |
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.
| Author | : Saad Mufti |
| Publisher | : |
| Total Pages | : |
| Release | : 2017 |
| Genre | : |
| ISBN | : |
| Author | : John Volakis |
| Publisher | : McGraw Hill Professional |
| Total Pages | : 449 |
| Release | : 2009-12-22 |
| Genre | : Technology & Engineering |
| ISBN | : 0071625542 |
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
| Author | : Kyohei Fujimoto |
| Publisher | : Cambridge University Press |
| Total Pages | : |
| Release | : 2014-01-09 |
| Genre | : Technology & Engineering |
| ISBN | : 1107354668 |
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.
| Author | : Douglas B. Miron |
| Publisher | : Elsevier |
| Total Pages | : 304 |
| Release | : 2006-03-22 |
| Genre | : Technology & Engineering |
| ISBN | : 0080498140 |
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
| Author | : Yikai Chen |
| Publisher | : John Wiley & Sons |
| Total Pages | : 294 |
| Release | : 2015-05-19 |
| Genre | : Technology & Engineering |
| ISBN | : 111903888X |
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.
| Author | : Sungkyun Lim |
| Publisher | : |
| Total Pages | : 252 |
| Release | : 2007 |
| Genre | : Antennas (Electronics) |
| ISBN | : |
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.
| Author | : Slawomir Koziel |
| Publisher | : Springer Science & Business Media |
| Total Pages | : 145 |
| Release | : 2014-02-12 |
| Genre | : Mathematics |
| ISBN | : 3319043676 |
This Brief reviews a number of techniques exploiting the surrogate-based optimization concept and variable-fidelity EM simulations for efficient optimization of antenna structures. The introduction of each method is illustrated with examples of antenna design. The authors demonstrate the ways in which practitioners can obtain an optimized antenna design at the computational cost corresponding to a few high-fidelity EM simulations of the antenna structure. There is also a discussion of the selection of antenna model fidelity and its influence on performance of the surrogate-based design process. This volume is suitable for electrical engineers in academia as well as industry, antenna designers and engineers dealing with computationally-expensive design problems.
| Author | : Jacob J. Adams |
| Publisher | : |
| Total Pages | : |
| Release | : 2011 |
| Genre | : |
| ISBN | : |
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.
| Author | : Slawomir Koziel |
| Publisher | : World Scientific |
| Total Pages | : 361 |
| Release | : 2016-11-18 |
| Genre | : Computers |
| ISBN | : 1786341492 |
This book addresses computationally-efficient multi-objective optimization of antenna structures using variable-fidelity electromagnetic simulations, surrogate modeling techniques, and design space reduction methods. Based on contemporary research, it formulates multi-objective design tasks, highlights related challenges in the context of antenna design, and discusses solution approaches. Specific focus is on providing methodologies for handling computationally expensive simulation models of antenna structures in the sense of their multi-objective optimization. Also given is a summary of recent developments in antenna design optimization using variable-fidelity simulation models. Numerous examples of real-world antenna design problems are provided along with discussions and recommendations for the readers interested in applying the considered methods in their design work.Written with researchers and students in mind, topics covered can also be applied across a broad spectrum of aeronautical, mechanical, electrical, biomedical and civil engineering. It is of particular interest to those dealing with optimization, computationally expensive design tasks and simulation-driven design.
