This book will appeal to scientists and engineers who are concerned with the design of microwave wideband devices and systems. For advanced (ultra)-wideband wireless systems, the necessity and design methodology of wideband filters will be discussed with reference to the inherent limitation in fractional bandwidth of classical bandpass filters. Besides the detailed working principles, a large number of design examples are demonstrated, which can be easily followed and modified by the readers to achieve their own desired specifications. Therefore, this book is of interest not only to students and researchers from academia, but also to design engineers in industry. With the help of complete design procedures and tabulated design parameters, even those with little filter design experience, will find this book to be a useful design guideline and reference, which can free them from tedious computer-aided full-wave electromagnetic simulations. Among different design proposals, wideband bandpass filters based on the multi-mode resonator have demonstrated many unparalleled attractive features, including a simple design methodology, compact size, low loss and good linearity in the wide passband, enhanced out-of-band rejection, and easy integration with other circuits/antennas. A conventional bandpass filter works under single dominant resonant modes of a few cascaded transmission line resonators and its operating bandwidth is widened via enhanced coupling between the adjacent resonators. However, this traditional approach needs an extremely high coupling degree of coupled-lines while producing a narrow upper stopband between the dominant and harmonic bands. As a sequence, the desired dominant passband is restricted to an extent less than 60% in fractional bandwidth. To circumvent these issues and break with the tradition, a filter based on the multiple resonant modes was initially introduced in 2000 by the first author of this book. Based on this novel concept, a new class of wideband filters with fractional bandwidths larger than 60% has been successfully developed so far. This book, presents and characterizes a variety of multi-mode resonators with stepped-impedance or loaded-stub configurations using the matured transmission line theory for development of advanced microwave wideband filters.

This book will appeal to scientists and engineers who are concerned with the design of microwave wideband devices and systems. For advanced (ultra)-wideband wireless systems, the necessity and design methodology of wideband filters will be discussed with reference to the inherent limitation in fractional bandwidth of classical bandpass filters. Besides the detailed working principles, a large number of design examples are demonstrated, which can be easily followed and modified by the readers to achieve their own desired specifications. Therefore, this book is of interest not only to students and researchers from academia, but also to design engineers in industry. With the help of complete design procedures and tabulated design parameters, even those with little filter design experience, will find this book to be a useful design guideline and reference, which can free them from tedious computer-aided full-wave electromagnetic simulations. Among different design proposals, wideband bandpass filters based on the multi-mode resonator have demonstrated many unparalleled attractive features, including a simple design methodology, compact size, low loss and good linearity in the wide passband, enhanced out-of-band rejection, and easy integration with other circuits/antennas. A conventional bandpass filter works under single dominant resonant modes of a few cascaded transmission line resonators and its operating bandwidth is widened via enhanced coupling between the adjacent resonators. However, this traditional approach needs an extremely high coupling degree of coupled-lines while producing a narrow upper stopband between the dominant and harmonic bands. As a sequence, the desired dominant passband is restricted to an extent less than 60% in fractional bandwidth. To circumvent these issues and break with the tradition, a filter based on the multiple resonant modes was initially introduced in 2000 by the first author of this book. Based on this novel concept, a new class of wideband filters with fractional bandwidths larger than 60% has been successfully developed so far. This book, presents and characterizes a variety of multi-mode resonators with stepped-impedance or loaded-stub configurations using the matured transmission line theory for development of advanced microwave wideband filters.

PREFACE ix1 INTRODUCTION 11.1 Background on UWB Technology 21.2 UWB Regulations 31.3 UWB Bandpass Filters 81.4 Organization of the Book 112 TRANSMISSION LINE CONCEPTS AND NETWORKS 182.1 Introduction 182.2 Transmission Line Theory 192.3 Microwave Network Parameters 262.4 Relative Theories of Network Analysis 422.5 Summary 523 CONVENTIONAL PARALLEL-COUPLED LINE FILTER 533.1 Introduction 533.2 Lumped-Element Lowpass Filter Prototype 543.3 Impedance and Frequency Transformation 653.4 Immittance Inverters 703.5 Lowpass Prototype Filter with Immittance Inverter 713.6 Parallel-Coupled Line Bandpass Filter 763.7 Summary 844 PLANAR TRANSMISSION LINE RESONATORS 854.1 Introduction 854.2 Uniform Impedance Resonator 874.3 Stepped Impedance Resonators 944.4 Multiple-Mode Resonator 1044.5 Summary 1135 MMR-BASED UWB BANDPASS FILTERS 1165.1 Introduction 1165.2 An Initial MMR-Based UWB Bandpass Filter 1185.3 UWB Bandpass Filters with Varied Geometries 1215.4 UWB Filters with Improved Out-of-Band Performance 1305.5 UWB Bandpass Filter with a Notch Band 1425.6 Summary 1466 SYNTHESIS APPROACH FOR UWB FILTERS 1496.1 Introduction 1496.2 Transfer Function 1506.3 Transmission Line Network with Pure Shunt/Series Stubs1526.4 Transmission Line Network with Hybrid Series and Shunt Stubs1636.5 MMR-Based UWB Filter with Parallel-Coupled Lines 1786.6 Summary 1877 OTHER TYPES OF UWB FILTERS 1887.1 Introduction 1887.2 UWB Filters with Highpass and Lowpass Filters 1887.3 UWB Filters with Optimum Shunt Short-Circuited Stubs 1917.4 UWB Filters with Quasi-Lumped Elements 1957.5 UWB Filters with Composite CPW and Microstrip Structure1977.6 UWB Filter with Microstrip Ring Resonator 1997.7 UWB Filter using Multilayer Structures 2037.8 UWB Filter with Substrate Integrated Waveguide (SIW) 2057.9 UWB Filter with Notch Band 2077.10 Summary 210References 210INDEX 214