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 Antennas with Non Foster Matching Networks written by James T. Aberle and published by Morgan & Claypool Publishers. This book was released on 2007-12-01 with total page 53 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 Non foster Impedance Matching and Loading Networks for Electrically Small Antennas written by Keum Su Song and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Lastly, this dissertation discusses a method to improve the performance of a small loop antenna by using a Non-Foster inductor loading. The Non-Foster loading network (located away from the input port of the antenna) is employed to improve the impedance mismatch and also maintain an omni-directional antenna pattern at higher frequencies than the case of a loop antenna with a Non-Foster matching network and a short loading (stands for a small loop antenna). Although the experimental radiation patterns are somewhat different from the simulated data, it is found that the measured antenna gain and SNR with the Non-Foster inductor loading are improved when compared to case with a short loading. To the best of our knowledge, it is the first time that a fabricated Non-Foster impedance loading network was applied to an actual antenna.

Download or read book Antennas with Non Foster Matching Networks written by James T. Aberle and published by Springer Nature. This book was released on 2022-06-01 with total page 47 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 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 Small Antenna Handbook written by Robert C. Hansen and published by John Wiley & Sons. This book was released on 2011-10-25 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 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.

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 Automated Broad and Narrow Band Impedance Matching for RF and Microwave Circuits written by Amal Banerjee and published by Springer. This book was released on 2018-10-06 with total page 109 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book presents a seamless and unified scheme for automating very complicated calculations required to design, evaluate performance characteristics of, and implement broadband and narrow band impedance matching sub-circuits. The results of these automated calculations (the component values of the impedance matching sub-circuit) are formatted as text SPICE(Simulation Program with Integrated Circuit Emphasis) input netlists. Readers then immediately can use any available SPICE simulator to measure the performance characteristics (DC response, transient response, frequency response, RMS power transferred from source to load, reflection coefficient insertion and transmission loss, ans standing wave ratio – SWR). The text SPICE netlist can be edited easily to fine-tune the performance characteristics, and perform design space exploration and “what-if” type of analyses. Presents details of a coherent, logical and seamless scheme to design and measure the performance characteristics of both broad and narrow band impedance matching sub-circuits; Relieves the designer from having to manually do complex, multi-step(therefore error-prone and time-consuming) calculations, especially those related to broadband impedance matching sub-circuit design; Provides SPICE input netlists, which enable readers to use any available SPICE simulator to estimate the performance characteristics.

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 Transformation Electromagnetics and Metamaterials written by Douglas H. Werner and published by Springer Science & Business Media. This book was released on 2013-07-19 with total page 500 pages. Available in PDF, EPUB and Kindle. Book excerpt: Transformation electromagnetics is a systematic design technique for optical and electromagnetic devices that enables novel wave-material interaction properties. The associated metamaterials technology for designing and realizing optical and electromagnetic devices can control the behavior of light and electromagnetic waves in ways that have not been conventionally possible. The technique is credited with numerous novel device designs, most notably the invisibility cloaks, perfect lenses and a host of other remarkable devices. Transformation Electromagnetics and Metamaterials: Fundamental Principles and Applications presents a comprehensive treatment of the rapidly growing area of transformation electromagnetics and related metamaterial technology with contributions on the subject provided by a collection of leading experts from around the world. On the theoretical side, the following questions will be addressed: “Where does transformation electromagnetics come from?,” “What are the general material properties for different classes of coordinate transformations?,” “What are the limitations and challenges of device realizations?,” and “What theoretical tools are available to make the coordinate transformation-based designs more amenable to fabrication using currently available techniques?” The comprehensive theoretical treatment will be complemented by device designs and/or realizations in various frequency regimes and applications including acoustic, radio frequency, terahertz, infrared, and the visible spectrum. The applications encompass invisibility cloaks, gradient-index lenses in the microwave and optical regimes, negative-index superlenses for sub-wavelength resolution focusing, flat lenses that produce highly collimated beams from an embedded antenna or optical source, beam concentrators, polarization rotators and splitters, perfect electromagnetic absorbers, and many others. This book will serve as the authoritative reference for students and researchers alike to the fast-evolving and exciting research area of transformation electromagnetics/optics, its application to the design of revolutionary new devices, and their associated metamaterial realizations.

Download or read book Non foster Antenna Matching Networks Using Reflection mode Negative group delay Networks written by Alhasan Ali Moftah Almahroug and published by . This book was released on 2018 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Non-Foster networks provide a possible route for broad band matching of antennas. The major challenges when designing non-Foster elements using conventional Negative Impedance Converters (NICs) arise from the stability concerns, due to the existence of the feedback in the circuitry and the generation of negative impedance. Therefore, investigation of alternative means for designing non-Foster elements which are more stable is imperative. This thesis presents a new perspective in designing non-Foster reactive elements based on negative group delay (NGD) networks. A novel reflection-mode NGD network is designed, fabricated and tested. Subsequently, a novel approach which contains a negative resistance amplifier and a Lange coupler is introduced to compensate the losses of the NGD networks. A simple equivalent circuit model (-L, -C) of the proposed NGD-based non-Foster network is presented and can be used to deploy the non-Foster network in an antenna matching network. Theoretical analysis based on Nyquist approach shows that stability can be achieved but practical implementation issues can cause stability problems. . Finally, approximate calculations of the non-linearity and noise performance addressing the operational limitations of the proposed circuit in transmit and receive applications have been introduced.

Download or read book The Design of Impedance Matching Networks for Broadband Antennas written by S. T. Li and published by . This book was released on 1987 with total page 84 pages. Available in PDF, EPUB and Kindle. Book excerpt: An interactive BASIC language computer program to aid in the design of a matching network for a broadband antenna is described. Guidelines for the design of a broadband matching network are presented. The Antenna Matching (ANTMAT) program provides a computer-aided design tool for determining network topology and component values of the networks. It improves the speed and accuracy of the broadband matching network design procedures. An optimization algorithm finds that the values of the components that minimize the input reflection coefficient. At first, the optimization algorithm with an exponential weighting function is employed for determining a list of network candidates (either a pi network for a T network) from which a network topology is selected. After a topology is specified, the optimization algorithm with other weighting function is used for finding optimum element values. Keywords include: Interactive computer program, Computer-aided design, Network topology, and Optimization algorithm.

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 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 Broadband Lossy Impedance Matching of Antennas written by Kaiming Li and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: In RF applications such as transmitters, amplifiers, receivers, and antennas, a task of vital importance is the design of an impedance matching network, one that can transfer the most power from the source to the load. Lossless matching networks at a single frequency have been well studied, while the broadband impedance matching problem was only defined 70 years ago. This dissertation provides a thorough background of the theory basis and design approaches in the history of broadband impedance matching. Lossless impedance matching optimization using the MATLAB Global Optimization Toolbox is discussed, and an approach combining brute-force techniques and the Real Frequency Technique is proposed. The bandwidth of a candidate 80-meter high-frequency dipole antenna has been increased from 4.1% to at least 15.0% after the optimization, with a Voltage Standing Wave Ratio (VSWR) of 2:1. In order to match the source and load over a wide band, a tradeoff is forced between the antenna gain and its bandwidth. The lossy impedance matching problem is investigated in the dissertation as a multi-objective optimization problem. Multiple optimization algorithms are used to find the Pareto front for a given lossy network topology. With equal weight on the objectives, the bandwidth of the dipole is further increased to 16.9%. This approach was applied to conformal antennas such as a low-profile bow-tie antenna close to a ground plane and compared with the new approach of using metamaterial inserted between the antenna and the ground plane. There is considerable interest and a main goal of this dissertation to find if another approach such as this lossy matching method could compete with the metamaterial technique. With lossy matching, the unnecessarily high gain of the antenna is traded in for a decrease in the reflection, increasing the bandwidth of the bow-tie to more than 70.7%, or [200MHz, 400MHz]. Considering the high cost of manufacturing metamaterial to achieve similar performance, the approach found for the first time in this dissertation is a iv significant breakthrough in the design and practicality of making future conformal and other types of antennas. The unique and innovative techniques utilized in this dissertation include performing lossless and lossy impedance matching optimization using results from more numerical platforms like FEKO and GNEC for various antenna configurations. In this dissertation topologies have been thoroughly explored including circuits with various numbers of elements and those including the insertion of lossy components into the lossless networks. Additionally, the latest nature-inspired optimization algorithms were applied to the lossy impedance matching problem and compared with the traditional algorithms.

Download or read book Realization of Broadband Matching Networks for Arbitrary Impedances written by B. K. Kinariwala and published by . This book was released on 1957 with total page 256 pages. Available in PDF, EPUB and Kindle. Book excerpt: