Artificial Transmission Lines for RF and Microwave Applications

Ferran Martin, Ferran Martín

• Publisher: Wiley
• Year: 2015
• Print ISBN: 9781118487600
• eBook ISBN: 9781119058373
• Edition: 1
• Topic: Technology & Engineering
• Subtopic: Microwaves
• Index: Technology & Engineering

This book presents and discusses alternatives to ordinary transmission lines for the design and implementation of advanced RF/microwave components in planar technology. This book is devoted to the analysis, study and applications of artificial transmission lines mostly implemented by means of a host line conveniently modified (e.g., with modulation of transverse dimensions, with etched patterns in the metallic layers, etc.) or with reactive loading, in order to achieve novel device functionalities, superior performance, and/or reduced size. The author begins with an introductory chapter dedicated to the fundamentals of planar transmission lines. Chapter 2 is focused on artificial transmission lines based on periodic structures (including non-uniform transmission lines and reactively-loaded lines), and provides a comprehensive analysis of the coupled mode theory. Chapters 3 and 4 are dedicated to artificial transmission lines inspired by metamaterials, or based on metamaterial concepts. These chapters include the main practical implementations of such lines and their circuit models, and a wide overview of their RF/microwave applications (including passive and active circuits and antennas). Chapter 5 focuses on reconfigurable devices based on tunable artificial lines, and on non-linear transmission lines. The chapter also introduces several materials and components to achieve tuning, including diode varactors, RF-MEMS, ferroelectrics, and liquid crystals. Finally, Chapter 6 covers other advanced transmission lines and wave guiding structures, such as electroinductive-/magnetoinductive-wave lines, common-mode suppressed balanced lines, lattice-network artificial lines, and substrate integrated waveguides. Artificial Transmission Lines for RF and Microwave Applications provides an in-depth analysis and discussion of artificial transmission lines, including design guidelines that can be useful to researchers, engineers and students.

1
FUNDAMENTALS OF PLANAR TRANSMISSION LINES

1.1 PLANAR TRANSMISSION LINES, DISTRIBUTED CIRCUITS, AND ARTIFICIAL TRANSMISSION LINES

In radiofrequency (RF) and microwave engineering, transmission lines are two-port networks used to transmit signals, or power, between two distant points (the source and the load) in a guided (in contrast to radiated) way. There are many types of transmission lines. Probably, the most well-known transmission line (at least for nonspecialists in RF and microwave engineering) is the coaxial line (Fig. 1.1), which consists of a pair of concentric conductors separated by a dielectric, and is typically used to feed RF/microwave components and to connect them to characterization and test equipment. Other planar transmission lines are depicted in Figure 1.2. There are many textbooks partially or entirely focused on transmission lines and their RF and microwave applications [1–8]. The author recommends these books to those readers interested in the topic of the present book (artificial transmission lines), which are not familiar with conventional (or ordinary) transmission lines. Nevertheless, the fundamentals of planar transmission lines are considered in this chapter for completeness and for better comprehension of the following chapters. As long as waveguides (and even optical fibers) do also carry electromagnetic (EM) waves and EM energy between two points, they can also be considered transmission lines. However, this book is entirely devoted to planar structures; and for this reason, waveguides are out of the scope of this chapter.

Figure 1.1 Perspective three-dimensional view of a coaxial transmission line. The relevant geometry parameters of the line are indicated, and ε_r is the relative permittivity (or dielectric constant) of the dielectric material.

Figure 1.2 Perspective three-dimensional view of the indicated planar transmission lines, and relevant geometry parameters. These transmission lines are used for the implementation of distributed circuits, where the shape and transverse dimensions (W, S, G) of the line (or set of lines and stubs) are determined in order to obtain the required line functionality.

Obviously, there are not transmission lines in natural form.¹ Transmission lines must be fabricated in order to satisfy certain requirements or specifications; in this sense, they are actually artificial (i.e., man-made) structures. However, the term artificial transmission line is restricted to a specific type of transmission lines, to distinguish them from the conventional ones.² Before discussing the definition and scope of the term artificial transmission line, let us now point out the different approaches for the study of planar (conventional) transmission lines. If the physical length of the transmission line is much smaller than the wavelength of the transmitted signals, the voltages and currents in the line are uniform, that is, they do not depend on the position in the line.³ Under these conditions, the voltages and currents are dictated by the Kirchhoff’s current and voltage laws and by the terminal equations of the lumped elements present...

Table of contents

• Cover
• Title page
• Table of Contents
• PREFACE
• ACKNOWLEDGMENTS
• 1 FUNDAMENTALS OF PLANAR TRANSMISSION LINES
• 2 ARTIFICIAL TRANSMISSION LINES BASED ON PERIODIC STRUCTURES
• 3 METAMATERIAL TRANSMISSION LINES: FUNDAMENTALS, THEORY, CIRCUIT MODELS, AND MAIN IMPLEMENTATIONS
• 4 METAMATERIAL TRANSMISSION LINES: RF/MICROWAVE APPLICATIONS
• 5 RECONFIGURABLE, TUNABLE, AND NONLINEAR ARTIFICIAL TRANSMISSION LINES
• 6 OTHER ADVANCED TRANSMISSION LINES
• Appendix A EQUIVALENCE BETWEEN PLANE WAVE PROPAGATION IN SOURCE-FREE, LINEAR, ISOTROPIC, AND HOMOGENEOUS MEDIA; TEM WAVE PROPAGATION IN TRANSMISSION LINES; AND WAVE PROPAGATION IN TRANSMISSION LINES DESCRIBED BY ITS DISTRIBUTED CIRCUIT MODEL
• Appendix B THE SMITH CHART
• Appendix C THE SCATTERING MATRIX
• Appendix D CURRENT DENSITY DISTRIBUTION IN A CONDUCTOR
• Appendix E DERIVATION OF THE SIMPLIFIED COUPLED MODE EQUATIONS AND COUPLING COEFFICIENT FROM THE DISTRIBUTED CIRCUIT MODEL OF A TRANSMISSION LINE
• Appendix F AVERAGING THE EFFECTIVE DIELECTRIC CONSTANT IN EBG-BASED TRANSMISSION LINES
• Appendix G PARAMETER EXTRACTION
• Appendix H SYNTHESIS OF RESONANT-TYPE METAMATERIAL TRANSMISSION LINES BY MEANS OF AGGRESSIVE SPACE MAPPING
• Appendix I CONDITIONS TO OBTAIN ALL-PASS X-TYPE AND BRIDGED-T NETWORKS
• ACRONYMS
• INDEX
• WILEY SERIES IN MICROWAVE AND OPTICAL ENGINEERING
• END USER LICENSE AGREEMENT