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This book gives a step-by-step presentation of a generalized transmission line method to study the far-zone radiation of antennas under a multilayer structure. Normally, a radiation problem requires a full wave analysis which may be time consuming. The beauty of the generalized transmission line method is that it transforms the radiation problem for a specific type of structure, say the multilayer structure excited by an antenna, into a circuit problem that can be efficiently analyzed. Using the Reciprocity Theorem and far-field approximation, the method computes the far-zone radiation due to a Hertzian dipole within a multilayer structure by solving an equivalent transmission line circuit. Since an antenna can be modeled as a set of Hertzian dipoles, the method could be used to predict the far-zone radiation of an antenna under a multilayer structure. The analytical expression for the far-zone field is derived for a structure with or without a polarizer. The procedure of obtaining the Hertzian dipole model that is required by the generalized transmission line method is also described. Several examples are given to demonstrate the capabilities, accuracy, and efficiency of this method. Table of Contents: Antennas Under a Multilayer Dielectric Slab / Antennas Under a Polarized Multilayer Structure / Hertzian Dipole Model for an Antenna / Bibliography / Biography
In recent years, transmitarray antennas have attracted growing interest with many antenna researchers. Transmitarrays combines both optical and antenna array theory, leading to a low profile design with high gain, high radiation efficiency, and versatile radiation performance for many wireless communication systems. In this book, comprehensive analysis, new methodologies, and novel designs of transmitarray antennas are presented. Detailed analysis for the design of planar space-fed array antennas is presented. The basics of aperture field distribution and the analysis of the array elements are described. The radiation performances (directivity and gain) are discussed using array theory approach, and the impacts of element phase errors are demonstrated. The performance of transmitarray design using multilayer frequency selective surfaces (M-FSS) approach is carefully studied, and the transmission phase limit which are generally independent from the selection of a specific element shape is revealed. The maximum transmission phase range is determined based on the number of layers, substrate permittivity, and the separations between layers. In order to reduce the transmitarray design complexity and cost, three different methods have been investigated. As a result, one design is performed using quad-layer cross-slot elements with no dielectric material and another using triple-layer spiral dipole elements. Both designs were fabricated and tested at X-Band for deep space communications. Furthermore, the radiation pattern characteristics were studied under different feed polarization conditions and oblique angles of incident field from the feed. New design methodologies are proposed to improve the bandwidth of transmitarray antennas through the control of the transmission phase range of the elements. These design techniques are validated through the fabrication and testing of two quad-layer transmitarray antennas at Ku-band. A single-feed quad-beam transmitarray antenna with 50 degrees elevation separation between the beams is investigated, designed, fabricated, and tested at Ku-band. In summary, various challenges in the analysis and design of transmitarray antennas are addressed in this book. New methodologies to improve the bandwidth of transmitarray antennas have been demonstrated. Several prototypes have been fabricated and tested, demonstrating the desirable features and potential new applications of transmitarray antennas.
Tunable Materials with Applications in Antennas and Microwaves is a stimulating topic in these modern times. With the explosion of the new generation of the wireless world, greater emphasis than ever before is being placed on the analysis and applications of modern materials. This book describes the characteristics of Ferrites and Ferroelectrics and introduces the reader to Multiferroics. Represents, in a simple manner, the solid state physics and explains the permittivity and permeability tensor characteristics for the tunable materials of infinite and finite dimensions. Gives the applications of tunable materials in resonators, filters, microstrips, striplines, antennas, phase shifters, capacitors, varactors, and frequency selective surfaces. Describes in detail the mathematical analysis for spin and magnetostatic waves for infinite medium, thin slab films, and finite circular discs. The analysis contains original work, which the reader may extend in the future. Provides multiferroics, which are ferrite and ferroelectric composites. Multiferroics are very promising tunable materials which are believed will offer many applications in the near future. Contains the planar transmission lines with analytic formulas for multilayer microstrips, transmission lines, and waveguides with isotropic as well as anisotropic dielectric and magnetic materials. Also, gives the formulas to analyze the layered category of transmission lines with multiferroics. This book is intended for antenna and microwave engineers as well as for graduate students of Materials Science and Engineering, Electrical & Computer Engineering, and Physics Departments.
This lecture discusses the use of graph models to represent reconfigurable antennas. The rise of antennas that adapt to their environment and change their operation based on the user's request hasn't been met with clear design guidelines. There is a need to propose some rules for the optimization of any reconfigurable antenna design and performance. Since reconfigurable antennas are seen as a collection of self-organizing parts, graph models can be introduced to relate each possible topology to a corresponding electromagnetic performance in terms of achieving a characteristic frequency of operation, impedance, and polarization. These models help designers understand reconfigurable antenna structures and enhance their functionality since they transform antennas from bulky devices into mathematical and software accessible models. The use of graphs facilitates the software control and cognition ability of reconfigurable antennas while optimizing their performance. This lecture also discusses the reduction of redundancy, complexity and reliability of reconfigurable antennas and reconfigurable antenna arrays. The full analysis of these parameters allows a better reconfigurable antenna implementation in wireless and space communications platforms. The use of graph models to reduce the complexity while preserving the reliability of reconfigurable antennas allow a better incorporation in applications such as cognitive radio, MIMO, satellite communications, and personal communication systems. A swifter response time is achieved with less cost and losses. This lecture is written for individuals who wish to venture into the field of reconfigurable antennas, with a little prior experience in this area, and learn how graph rules and theory, mainly used in the field of computer science, networking, and control systems can be applied to electromagnetic structures. This lecture will walk the reader through a design and analysis process of reconfigurable antennas using graph models with a practical and theoretical outlook.
This book presents the developments and potential applications of Meta-Smith charts, which can be applied to practical and useful transmission line problems (e.g., metamaterial transmission lines and nonreciprocal transmission lines). These problems are beyond the capability of the standard Smith chart to be applied effectively. As any RF engineer is aware, a key property of the Smith chart is the insight it provides, even in very complex design processes. Like the Smith chart, Meta-Smith charts provide a useful way of visualizing transmission line phenomena. They provide useful physical insight, and they can also assist in solving related problems effectively. This book can be used as a companion guide in studying Microwave Engineering for senior undergraduate students as well as for graduate students. It is also recommended for researchers in the RF community, especially those working with periodic transmission line structures and metamaterial transmission lines. Problems are also provided at the end of each chapter for readers to gain a better understanding of material presented in this book. Table of Contents: Essential Transmission Line Theory / Theory of CCITLs / Theory of BCITLs / Meta-Smith Charts for CCITLs and BCITLs / Applications of Meta-Smith Charts
In recent years, transmitarray antennas have attracted growing interest with many antenna researchers. Transmitarrays combines both optical and antenna array theory, leading to a low profile design with high gain, high radiation efficiency, and versatile radiation performance for many wireless communication systems. In this book, comprehensive analysis, new methodologies, and novel designs of transmitarray antennas are presented. Detailed analysis for the design of planar space-fed array antennas is presented. The basics of aperture field distribution and the analysis of the array elements are described. The radiation performances (directivity and gain) are discussed using array theory approach, and the impacts of element phase errors are demonstrated. The performance of transmitarray design using multilayer frequency selective surfaces (M-FSS) approach is carefully studied, and the transmission phase limit which are generally independent from the selection of a specific element shape is revealed. The maximum transmission phase range is determined based on the number of layers, substrate permittivity, and the separations between layers. In order to reduce the transmitarray design complexity and cost, three different methods have been investigated. As a result, one design is performed using quad-layer cross-slot elements with no dielectric material and another using triple-layer spiral dipole elements. Both designs were fabricated and tested at X-Band for deep space communications. Furthermore, the radiation pattern characteristics were studied under different feed polarization conditions and oblique angles of incident field from the feed. New design methodologies are proposed to improve the bandwidth of transmitarray antennas through the control of the transmission phase range of the elements. These design techniques are validated through the fabrication and testing of two quad-layer transmitarray antennas at Ku-band. A single-feed quad-beam transmitarray antenna with 50 degrees elevation separation between the beams is investigated, designed, fabricated, and tested at Ku-band. In summary, various challenges in the analysis and design of transmitarray antennas are addressed in this book. New methodologies to improve the bandwidth of transmitarray antennas have been demonstrated. Several prototypes have been fabricated and tested, demonstrating the desirable features and potential new applications of transmitarray antennas.
Issues for 1973- cover the entire IEEE technical literature.