Preface xiii Acknowledgments xvii 1 Fundamentals of Planar Transmission Lines 1 1.1 Planar Transmission Lines Distributed Circuits and Artificial Transmission Lines 1 1.2 Distributed Circuit Analysis and Main Transmission Line Parameters 5 1.3 Loaded (Terminated) Transmission Lines 8 1.4 Lossy Transmission Lines 16 1.4.1 Dielectric Losses: The Loss Tangent 19 1.4.2 Conductor Losses: The Skin Depth 25 1.5 Comparative Analysis of Planar Transmission Lines 28 1.6 Some Illustrative Applications of Planar Transmission Lines 31 1.6.1 Semilumped Transmission Lines and Stubs and Their Application to Low-Pass and Notch Filters 31 1.6.2 Low-Pass Filters Based on Richard’s Transformations 39 1.6.3 Power Splitters Based on λ/4 Lines 40 1.6.4 Capacitively Coupled λ/2 Resonator Bandpass Filters 42 References 44 2 Artificial Transmission Lines based on Periodic Structures 47 2.1 Introduction and Scope 47 2.2 Floquet Analysis of Periodic Structures 48 2.3 The Transfer Matrix Method 53 2.3.1 Dispersion Relation 54 2.3.2 Bloch Impedance 56 2.3.3 Effects of Asymmetry in the Unit Cell through an Illustrative Example 60 2.3.4 Comparison between Periodic Transmission Lines and Conventional Lines 62 2.3.5 The Concept of Iterative Impedance 63 2.4 Coupled Mode Theory 64 2.4.1 The Cross-Section Method and the Coupled Mode Equations 65 2.4.2 Relation between the Complex Mode Amplitudes and S-Parameters 69 2.4.3 Approximate Analytical Solutions of the Coupled Mode Equations 71 2.4.4 Analytical Expressions for Relevant Parameters of EBG Periodic Structures 77 2.4.5 Relation between the Coupling Coefficient and the S-Parameters 79 2.4.6 Using the Approximate Solutions of the Coupled Mode Equations 80 2.5 Applications 86 2.5.1 Applications of Periodic Nonuniform Transmission Lines 86 2.5.1.1 Reflectors 86 2.5.1.2 High-Q Resonators 92 2.5.1.3 Spurious Suppression in Planar Filters 93 2.5.1.4 Harmonic Suppression in Active Circuits 95 2.5.1.5 Chirped Delay Lines 99 2.5.2 Applications of Reactively Loaded Lines: The Slow Wave Effect 102 2.5.2.1 Compact CPW Bandpass Filters with Spurious Suppression 105 2.5.2.2 Compact Microstrip Wideband Bandpass Filters with Ultrawideband Spurious Suppression 108 References 114 3 Metamaterial Transmission Lines: Fundamentals Theory Circuit Models and Main Implementations 119 3.1 Introduction Terminology and Scope 119 3.2 Effective Medium Metamaterials 122 3.2.1 Wave Propagation in LH Media 123 3.2.2 Losses and Dispersion in LH Media 125 3.2.3 Main Electromagnetic Properties of LH Metamaterials 127 3.2.3.1 Negative Refraction 128 3.2.3.2 Backward Cerenkov Radiation 129 3.2.4 Synthesis of LH Metamaterials 131 3.2.4.1 Negative Effective Permittivity Media: Wire Media 132 3.2.4.2 Negative Effective Permeability Media: SRRs 136 3.2.4.3 Combining SRRs and Metallic Wires: One-Dimensional LH Medium 139 3.3 Electrically Small Resonators for Metamaterials and Microwave Circuit Design 141 3.3.1 Metallic Resonators 142 3.3.1.1 The Non-Bianisotropic SRR (NB-SRR) 142 3.3.1.2 The Broadside-Coupled SRR (BC-SRR) 142 3.3.1.3 The Double-Slit SRR (DS-SRR) 143 3.3.1.4 The Spiral Resonator (SR) 144 3.3.1.5 The Folded SIR 144 3.3.1.6 The Electric LC Resonator (ELC) 145 3.3.1.7 The Open Split-Ring Resonator (OSRR) 146 3.3.2 Applying Duality: Complementary Resonators 146 3.3.2.1 Complementary Split-Ring Resonator (CSRR) 147 3.3.2.2 Open Complementary Split-Ring Resonator (OCSRR) 149 3.4 Canonical Models of Metamaterial Transmission Lines 149 3.4.1 The Dual Transmission Line Concept 150 3.4.2 The CRLH Transmission Line 154 3.4.3 Other CRLH Transmission Lines 158 3.4.3.1 The Dual CRLH (D-CRLH) Transmission Line 158 3.4.3.2 Higher-Order CRLH and D-CRLH Transmission Lines 159 3.5 Implementation of Metamaterial Transmission Lines and Lumped-Element Equivalent Circuit Models 162 3.5.1 CL-Loaded Approach 162 3.5.2 Resonant-Type Approach 166 3.5.2.1 Transmission Lines based on SRRs 167 3.5.2.2 Transmission Lines based on CSRRs 177 3.5.2.3 Inter-Resonator Coupling: Effects and Modeling 183 3.5.2.4 Effects of SRR and CSRR Orientation: Mixed Coupling 191 3.5.2.5 Transmission Lines based on OSRRs and OCSRRs 195 3.5.2.6 Synthesis Techniques 203 3.5.3 The Hybrid Approach 204 References 206 4 Metamaterial Transmission Lines: RF/Microwave Applications 214 4.1 Introduction 214 4.2 Applications of CRLH Transmission Lines 215 4.2.1 Enhanced Bandwidth Components 215 4.2.1.1 Principle and Limitations 215 4.2.1.2 Illustrative Examples 219 4.2.2 Dual-Band and Multiband Components 225 4.2.2.1 Principle for Dual-Band and Multiband Operation 227 4.2.2.2 Main Approaches for Dual-Band Device Design and Illustrative Examples 228 4.2.2.3 Quad-Band Devices based on Extended CRLH Transmission Lines 246 4.2.3 Filters and Diplexers 250 4.2.3.1 Stopband Filters based on SRR- and CSRR-Loaded Lines 250 4.2.3.2 Spurious Suppression in Distributed Filters 251 4.2.3.3 Narrow Band Bandpass Filters and Diplexers Based on Alternate Right-/Left-Handed Unit Cells 255 4.2.3.4 Compact Bandpass Filters based on the Hybrid Approach 258 4.2.3.5 Highpass Filters Based on Balanced CRLH Lines 270 4.2.3.6 Wideband Filters Based on OSRRs and OCSRRs 270 4.2.3.7 Elliptic Lowpass Filters Based on OCSRRs 277 4.2.4 Leaky Wave Antennas (LWA) 282 4.2.5 Active Circuits 290 4.2.5.1 Distributed Amplifiers 290 4.2.5.2 Dual-Band Recursive Active Filters 298 4.2.6 Sensors 300 4.3 Transmission Lines with Metamaterial Loading and Applications 303 4.3.1 Multiband Planar Antennas 304 4.3.1.1 Multiband Printed Dipole and Monopole Antennas 304 4.3.1.2 Dual-Band UHF-RFID Tags 310 4.3.2 Transmission Lines Loaded with Symmetric Resonators and Applications 314 4.3.2.1 Symmetry Properties: Working Principle for Sensors and RF Bar Codes 315 4.3.2.2 Rotation Displacement and Alignment Sensors 316 4.3.2.3 RF Bar Codes 324 References 327 5 Reconfigurable Tunable and Nonlinear Artificial Transmission Lines 339 5.1 Introduction 339 5.2 Materials Components and Technologies to Implement Tunable Devices 339 5.2.1 Varactor Diodes Schottky Diodes PIN Diodes and Heterostructure Barrier Varactors 340 5.2.2 RF-MEMS 342 5.2.3 Ferroelectric Materials 344 5.2.4 Liquid Crystals 346 5.3 Tunable and Reconfigurable Metamaterial Transmission Lines and Applications 347 5.3.1 Tunable Resonant-Type Metamaterial Transmission Lines 347 5.3.1.1 Varactor-Loaded Split Rings and Applications 347 5.3.1.2 Tunable SRRs and CSRRs Based on RF-MEMS and Applications 362 5.3.1.3 Metamaterial Transmission Lines Based on Ferroelectric Materials 375 5.3.2 Tunable CL-Loaded Metamaterial Transmission Lines 377 5.3.2.1 Tunable Phase Shifters 378 5.3.2.2 Tunable Leaky Wave Antennas (LWA) 381 5.4 Nonlinear Transmission Lines (NLTLs) 385 5.4.1 Model for Soliton Wave Propagation in NLTLs 386 5.4.2 Numerical Solutions of the Model 391 References 395 6 Other Advanced Transmission Lines 402 6.1 Introduction 402 6.2 Magnetoinductive-wave and Electroinductive-wave Delay Lines 402 6.2.1 Dispersion Characteristics 403 6.2.2 Applications: Delay Lines and Time-Domain Reflectometry-Based Chipless Tags for RFID 406 6.3 Balanced Transmission Lines with Common-Mode Suppression 411 6.3.1 Strategies for Common-Mode Suppression 411 6.3.1.1 Differential Lines Loaded with Dumbbell-Shaped Slotted Resonators 412 6.3.1.2 Differential Lines Loaded with CSRRs 412 6.3.2 CSRR- and DS-CSRR-Based Differential Lines with Common-Mode Suppression: Filter Synthesis and Design 414 6.3.3 Applications of CSRR and DS-CSRR-Based Differential Lines 418 6.3.3.1 Differential Line with Common-Mode Suppression 418 6.3.3.2 Differential Bandpass Filter with Enhanced Common-Mode Rejection 421 6.3.4 Balanced Filters with Inherent Common-Mode Suppression 421 6.3.4.1 Balanced Bandpass Filters Based on OSRRs and OCSRRs 423 6.3.4.2 Balanced Bandpass Filters Based on Mirrored SIRs 425 6.4 Wideband Artificial Transmission Lines 429 6.4.1 Lattice Network Transmission Lines 429 6.4.1.1 Lattice Network Analysis 430 6.4.1.2 Synthesis of Lattice Network Artificial Transmission Lines 434 6.4.1.3 The Bridged-T Topology 437 6.4.2 Transmission Lines Based on Non-Foster Elements 439 6.5 Substrate-Integrated Waveguides and Their Application to Metamaterial Transmission Lines 441 6.5.1 SIWs with Metamaterial Loading and Applications to Filters and Diplexers 444 6.5.2 CRLH Lines Implemented in SIW Technology and Applications 445 References 454 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 460 Appendix B. The Smith Chart 468 Appendix C. The Scattering Matrix 474 Appendix D. Current Density Distribution in a Conductor 480 Appendix E. Derivation of the Simplified Coupled Mode Equations and Coupling Coefficient from the Distributed Circuit Model of a Transmission Line 482 Appendix F. Averaging the Effective Dielectric Constant in EBG-Based Transmission Lines 484 Appendix G. Parameter Extraction 486 Appendix H. Synthesis of Resonant-Type Metamaterial Transmission Lines by Means of Aggressive Space Mapping 491 Appendix I. Conditions to Obtain All-Pass X-Type and Bridged-T Networks 503 Acronyms 505 Index 508

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. Ferran Martín is a Full Professor of Electronics in the Departament d’Enginyeria Electrònica at the Universitat Autònoma de Barcelona (UAB) in Spain. He is the head of the Microwave Engineering, Metamaterials and Antennas Group (GEMMA) at UAB and the director of CIMITEC, a research Center on Metamaterials. Dr. Martín has generated over 450 book chapters, journal papers and conference contributions (most of them on topics related to the book), and has supervised 14 PhDs. He holds one of the Parc de Recerca UAB/Santander Technology Transfer Chairs at UAB, and has been the recipient of the Duran Farell Prize (2006) and the ICREA Academia Award (2008 and 2013). He is IEEE Fellow since 2012.