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 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 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 Antennas with Non Foster Matching Networks written by James T. Aberle and published by Morgan & Claypool Publishers. This book was released on 2007 with total page 54 pages. Available in PDF, EPUB and Kindle. Book excerpt: Most antenna engineers are likely to believe that antennas are one technology that is more or less impervious to the rapidly advancing semiconductor industry. However, as demonstrated in this lecture, there is a way to incorporate active components into an antenna and transform it into a new kind of radiating structure that can take advantage of the latest advances in analog circuit design. The approach for making this transformation is to make use of non-Foster circuit elements in the matching network of the antenna. By doing so, we are no longer constrained by the laws of physics that apply to passive antennas. However, we must now design and construct very touchy active circuits. This new antenna technology is now in its infancy. The contributions of this lecture are (1) to summarize the current state-of-the-art in this subject, and (2) to introduce some new theoretical and practical tools for helping us to continue the advancement of this technology.
Download or read book Electrically Small Near Field Resonant Parasitic NFRP Antennas Augmented with Passive and Active Circuit Elements to Enhance Their Functionality written by Ning Zhu and published by . This book was released on 2013 with total page 308 pages. Available in PDF, EPUB and Kindle. Book excerpt: Metamaterials have drawn considerable attention because they can exhibit epsilon-negative (ENG) and/or mu-negative (MNG) properties, which in turn can lead to exotic physical effects that can enable interesting, practical applications. For instance, ENG and MNG properties can be engineered to yield double negative (DNG) properties, such as a negative index of refraction, which leads to flat lenses. Similarly, their extreme versions enable cloaking effects. Inspired by such metamaterial properties, a promising methodology has been developed to design electrically small antennas (ESAs). These ESAs use unit cells of metamaterials as their near-field resonant parasitic (NFRP) elements. This new metamaterial-inspired antenna miniaturization method is extended in this dissertation by augmenting the antenna designs with circuits. A rectifying circuit augmentation is used to achieve electrically small, high efficiency rectenna systems. Rectennas are the enabling components of power harvesting and wireless power transmission systems. Electrically small, integrated rectennas have become popular and in demand for several wireless applications including sensor networks and bio-implanted devices. Four global positioning system (GPS) L1 frequency (1.5754 GHz) rectenna systems were designed, fabricated and measured: three resistor-loaded and one supercapacitor-loaded. The simulated and measured results will be described; good agreement between them was obtained. The NFRP ESAs are also augmented with active, non-Foster elements in order to overcome the physical limits of the impedance bandwidth of passive ESA systems. Unlike conventional active external matching network approaches, the non-Foster components are incorporated directly into the NFRP element of the ESA. Three 300 MHz non-Foster circuit-augmented broadband, ESA systems were demonstrated: an Egyptian axe monopole (EAM) antenna, an Egyptian axe dipole (EAD) antenna, and a protractor antenna. The simulated and measured results will be described; reasonable agreement between them was obtained. Moreover, a deeper practical engineering understanding of how lumped components with tighter tolerances, more accurate transistor models, and integrated circuit-based implementations will lead to more satisfactory performance characteristics of the non-Foster circuit-augmented ESAs was accomplished and is also reported.
Download or read book Compendium On Electromagnetic Analysis From Electrostatics To Photonics Fundamentals And Applications For Physicists And Engineers In 5 Volumes written by and published by World Scientific. This book was released on 2020-06-15 with total page 2064 pages. Available in PDF, EPUB and Kindle. Book excerpt: The five-volume set may serve as a comprehensive reference on electromagnetic analysis and its applications at all frequencies, from static fields to optics and photonics. The material includes micro- and nanomagnetics, the new generation of electric machines, renewable energy, hybrid vehicles, low-noise motors; antennas and microwave devices, plasmonics, metamaterials, lasers, and more.Written at a level accessible to both graduate students and engineers, Electromagnetic Analysis is a comprehensive reference, covering methods and applications at all frequencies (from statics to optical). Each volume contains pedagogical/tutorial material of high archival value as well as chapters on state-of-the-art developments.
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 Non foster Circuit Design and Stability Analysis for Wideband Antenna Applications written by Aseim M. N. Elfrgani and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: In recent years, there has been a great interest in wide-band small antennas for wireless communication in both ground and airborne applications. Electrically small antennas; however, are narrow bandwidth since they exhibit high a quality factor (Q). Therefore, matching networks are required to improve their input impedance and radiation characteristics. Unfortunately, due to gain-bandwidth restrictions, wideband matching cannot be achieved using passive networks unless a high order matching network is used. Fortunately, the so-called non-Foster circuits (NFCs) employ active networks to bypass the well-known gain-bandwidth restrictions derived by Bode-Fano. Although NFCs can be very useful in numerous microwave and antenna applications, they are difficult to design because they are potentially instable. Consequently, an accurate and efficient systematic stability assessment is necessary during the design process to predict any undesired behavior. In this dissertation, the design, stability, and measurement of two non-Foster matching networks for two different small monopole antennas, a non-Foster circuit embedded within half loop antenna, a combination of Foster and non-Foster matching network for small monopole antenna are presented. A third circuit; namely, a non-Foster coupling network for a two-element monopole array is also presented for phase enhancement applications. It all examples, the NFCs substantially improve the antenna's performance over a wide frequency band.
Download or read book Modern Small Antennas written by Kyohei Fujimoto and published by Cambridge University Press. This book was released on 2013 with total page 491 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 Electrically Small Superdirective and Superconducting Antennas written by R. C. Hansen and published by Wiley-Interscience. This book was released on 2006-06-30 with total page 0 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 Non foster Impedances as Active Broadband Matching Networks for Electrically Small Antennas written by Robert L. Romak and published by . This book was released on 2006 with total page 244 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Non Foster Circuits for High Performance Antennas written by Minu Mariam Jacob and published by . This book was released on 2016 with total page 113 pages. Available in PDF, EPUB and Kindle. Book excerpt: The demand for miniaturized, broadband communication systems has created a need for electrically small, broadband antennas. However, all passive electrically small antennas have a fundamental gain-bandwidth limitation related to their electrical size, as first described by Wheeler and Chu. This limitation can be overcome using active non-Foster circuits (negative inductors and/or negative capacitors), which can deliver a broadband input match with active matching techniques, or can help reduce phase dispersion using negative delay effects. This thesis will illustrate the advantages of non-Foster circuits in obtaining broadband small antennas, in addition to examining their practical limitations due to noise in receive applications, and nonlinearity in transmit applications.
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 Antenna Engineering Handbook written by John Volakis and published by McGraw Hill Professional. This book was released on 2018-11-05 with total page 1424 pages. Available in PDF, EPUB and Kindle. Book excerpt: The gold-standard reference on the design and application of classic and modern antennas—fully updated to reflect the latest advances and technologiesThis new edition of the “bible of antenna engineering” has been updated to provide start-to-finish coverage of the latest innovations in antenna design and application. You will find in-depth discussion of antennas used in modern communication systems, mobile and personal wireless technologies, satellites, radar deployments, flexible electronics, and other emerging technologies, including 5G, terahertz, and wearable electronics. Antenna Engineering Handbook, Fifth Edition, is bolstered by real-world examples, hundreds of illustrations, and an emphasis on the practical aspects of antennas.Featuring 60 chapters and contributions from more than 80 renowned experts, this acclaimed resource is edited by one of the world’s leading antenna authorities. This edition features all of the classic antenna types, plus new and emerging designs, with 13 all-new chapters and important updates to nearly all chapters from past editions.Antenna Engineering Handbook, Fifth Edition, clearly explains cutting-edge applications in WLANs, automotive systems, PDAs, and handheld devices, making it an indispensable companion for today’s antenna practitioners and developers.Coverage includes:•Antenna basics and classic antennas•Design approaches for antennas and arrays•Wideband and multiband antennas•Antennas for mobile devices and PDAs, automotive applications, and aircraft•Base station and smart antennas•Beamforming and 5G antennas•Millimeter-wave and terahertz antennas•Flexible, wearable, thin film, origami, dielectric, and on-chip antennas•MIMO antennas and phased arrays•Direction-finding and GPS antennas•Active antennas•Low-profile wideband antennas•Nanoantennas•Reflectors and other satellite and radio-telescope antennas•Low-frequency, HF, VHF, UHF, ECM, and ESM antennas•Impedance-matching techniques and material characteristics•Metastructured and frequency selective surfaces•Propagation and guided structures•Computational techniques and toolsets•Indoor and outdoor measurements
Download or read book Direct Antenna Modulation A Novel Pathway in Developing High Efficiency Bandwidth Electrically Small Antennas written by Jean Paul Santos and published by . This book was released on 2021 with total page 118 pages. Available in PDF, EPUB and Kindle. Book excerpt: The increasing need to improve bandwidth and efficiency in antennas is a continuous topic of research in RF systems. However, when it comes to physical platforms that are electrically small relative to the desired frequency of operation, balancing miniaturization, bandwidth, and efficiency is both challenging and often counterintuitive. To overcome these challenges, this dissertation proposes utilizing a Direct Antenna Modulated (DAM) electrically small antenna (ESA). Here, we propose using efficiency-bandwidth product in theoretically analyzing and in measuring the improvement of DAM over a conventional capacitively loaded loop antenna (CLLA). To quantify the benefits of DAM, a prototyped antenna with DAM (0.0275 x 0.0251 ) was designed and successfully transmits a Binary-Frequency Shift Keying (BFSK) signal centered at 75 MHz. Though transistor parasitics reduce the possible efficiency-bandwidth product improvement, , of DAM, measurements show the key importance of maintaining proper switching synchronization to achieve system bandwidths beyond the antenna's impedance bandwidth. The DAM system achieves significant measured efficiency-bandwidth product improvement, , up to 5 over bit rates of 700 kbps to 7 Mbps. Moreover, another important characteristic in these transmitters is their power handling capability. Therefore, the BFSK DAM system was also simulated and tested up to 40 dBm of input RF power. Both the simulations and measurements show the capability of DAM to transmit up to 40 dBm due to the complementary symmetrical topology of the antenna. Furthermore, to improve the spectral efficiency of BFSK DAM, another prototyped antenna, 0.018 x 0.02 , was designed to transmit a 4FSK signal at 35 MHz. Because 4FSK is a higher order modulation technique, the design can exhibit twice the bit rate of a BFSK DAM system. These results show that such a topology provides a roadmap in attaining even higher modulation orders, thus, higher spectral efficiency.
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 Design and Applications of Active Integrated Antennas written by Mohammad S. Sharawi and published by Artech House. This book was released on 2018-05-31 with total page 280 pages. Available in PDF, EPUB and Kindle. Book excerpt: This comprehensive new resource guides professionals in the latest methods used when designing active integrated antennas (AIA) for wireless communication devices for various standards. This book provides complete design procedures for the various elements of such active integrated antennas such as the matching network, the amplifier/active element as well as the antenna. This book offers insight into how active integration and co-design between the active components (amplifier, oscillator, mixer, diodes) and the antenna can provide better power transfer, higher gains, increased efficiencies, switched beam patterns and smaller design footprints. It introduces the co-design approach of active integrated antennas and its superior performance over conventional methods. Complete design examples are given of active integrated antenna systems for narrow and wideband applications as well as for multiple-input-multiple-output (MIMO) systems. Readers find the latest design methods for narrow and broadband RF matching networks. This book provides a complete listing of performance metrics for active integrated antennas. The book serves as a complete reference and design guide in the area of AIA.
