Synthesis Lectures on Antennas – serie

One of the main objectives of this lecture is to summarize the results of recent research activities of the authors on the subject of implanted antennas for medical wireless communication systems.

Most antenna engineers are likely to believe that antennas are one technology that is more or less impervious to the rapidly advancing semiconductor industry.

In fact, smart antenna systems comprise several critical areas such as individual antenna array design, signal processing algorithms, space-time processing, wireless channel modeling and coding, and network performance.

Scanning arrays present the radar or communications engineer with the ultimate in antenna flexibility.

This lecture explores the emerging area of reconfigurable antennas from basic concepts that provide insight into fundamental design approaches to advanced techniques and examples that offer important new capabilities for next-generation applications. Antennas are necessary and critical components of communication and radar systems, but sometimes their inability to adjust to new operating scenarios can limit system performance. Making antennas reconfigurable so that their behavior can adapt with changing system requirements or environmental conditions can ameliorate or eliminate these restrictions and provide additional levels of functionality for any system. For example, reconfigurable antennas on portable wireless devices can help to improve a noisy connection or redirect transmitted power to conserve battery life. In large phased arrays, reconfigurable antennas could be used to provide additional capabilities that may result in wider instantaneous frequency bandwidths, more extensive scan volumes, and radiation patterns with more desirable side lobe distributions. Written for individuals with a range of experience, from those with only limited prior knowledge of antennas to those working in the field today, this lecture provides both theoretical foundations and practical considerations for those who want to learn more about this exciting subject.Contents: Introduction / Definitions of Critical Parameters for Antenna Operation / Linkage Between Frequency Response and Radiation Characteristics: Implications for Reconfigurable Antennas / Methods for Achieving Frequency Response Reconfigurability / Methods for Achieving Polarization Reconfigurability / Methods for Achieving Radiation Pattern Reconfigurability / Methods for Achieving Compound Reconfigurable Antennas / Practical Issues for Implementing Reconfigurable Antennas / Conclusions and Directions for Future work

Advanced communication scenarios demand the development of new systemswhere antenna theory, channel propagation and communication models are seen from a common perspective as a way to understand and optimize the system as a whole. In this context, a comprehensive multiantenna formulation for multiple-input multiple-output systems is presented with a special emphasis on the connection of the electromagnetic and communication principles.Starting from the capacity for amultiantenna system, the book reviews radiation, propagation, and communicationmechanisms, paying particular attention to the vectorial, directional, and timefrequency characteristics of the wireless communication equation for low- and high-scattering environments. Based on the previous concepts, different space—time methods for diversity and multiplexing applications are discussed, multiantenna modeling is studied, and specific tools are introduced to analyze the antenna coupling mechanisms and formulate appropriate decorrelation techniques.Miniaturization techniques for closely spaced antennas are studied, and its fundamental limits and optimization strategies are reviewed. Finally, different practical multiantenna topologies for new communication applications are presented, and its main parameters discussed.A relevant feature is a collection of synthesis exercises that review the main topics of the book and introduces state-of-the art system architectures and parameters, facilitating its use either as a text book or as a support tool for multiantenna systems design.Table of Contents: Principles of Multiantenna Communication Systems / The Radio Channel for MIMO Communication Systems / Coding Theory for MIMO Communication Systems / Antenna Modeling for MIMO Communication Systems / Design of MPAs for MIMO Communication Systems / Design Examples and Performance Analysis of Different MPAs / References / List of Acronyms / List of Symbols / Operators and Mathematical Symbols

This book provides an introduction to narrowband array signal processing, classical and subspace-based direction of arrival (DOA) estimation with an extensive discussion on adaptive direction of arrival algorithms.

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.

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).

This lecture discusses the use of graph models to represent reconfigurable antennas. 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.

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 ofa 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.