Microwave Bandpass Filters for Wideband Communications: (Wiley Series in Microwave and Optical Engineering)

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.

Table of Contents:
PREFACE ix 1 INTRODUCTION 1 1.1 Background on UWB Technology 2 1.2 UWB Regulations 3 1.3 UWB Bandpass Filters 8 1.4 Organization of the Book 11 2 TRANSMISSION LINE CONCEPTS AND NETWORKS 18 2.1 Introduction 18 2.2 Transmission Line Theory 19 2.3 Microwave Network Parameters 26 2.4 Relative Theories of Network Analysis 42 2.5 Summary 52 3 CONVENTIONAL PARALLEL-COUPLED LINE FILTER 53 3.1 Introduction 53 3.2 Lumped-Element Lowpass Filter Prototype 54 3.3 Impedance and Frequency Transformation 65 3.4 Immittance Inverters 70 3.5 Lowpass Prototype Filter with Immittance Inverter 71 3.6 Parallel-Coupled Line Bandpass Filter 76 3.7 Summary 84 4 PLANAR TRANSMISSION LINE RESONATORS 85 4.1 Introduction 85 4.2 Uniform Impedance Resonator 87 4.3 Stepped Impedance Resonators 94 4.4 Multiple-Mode Resonator 104 4.5 Summary 113 5 MMR-BASED UWB BANDPASS FILTERS 116 5.1 Introduction 116 5.2 An Initial MMR-Based UWB Bandpass Filter 118 5.3 UWB Bandpass Filters with Varied Geometries 121 5.4 UWB Filters with Improved Out-of-Band Performance 130 5.5 UWB Bandpass Filter with a Notch Band 142 5.6 Summary 146 6 SYNTHESIS APPROACH FOR UWB FILTERS 149 6.1 Introduction 149 6.2 Transfer Function 150 6.3 Transmission Line Network with Pure Shunt/Series Stubs 152 6.4 Transmission Line Network with Hybrid Series and Shunt Stubs 163 6.5 MMR-Based UWB Filter with Parallel-Coupled Lines 178 6.6 Summary 187 7 OTHER TYPES OF UWB FILTERS 188 7.1 Introduction 188 7.2 UWB Filters with Highpass and Lowpass Filters 188 7.3 UWB Filters with Optimum Shunt Short-Circuited Stubs 191 7.4 UWB Filters with Quasi-Lumped Elements 195 7.5 UWB Filters with Composite CPW and Microstrip Structure 197 7.6 UWB Filter with Microstrip Ring Resonator 199 7.7 UWB Filter using Multilayer Structures 203 7.8 UWB Filter with Substrate Integrated Waveguide (SIW) 205 7.9 UWB Filter with Notch Band 207 7.10 Summary 210 References 210 INDEX 214

About the Author :
LEI ZHU, PhD, is Associate Professor at the School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore. Dr. Zhu was the first to introduce an MMR-based filter in 2000, which has since spurred the successful development of a new class of wideband filters with fractional bandwidths larger than 60 percent. SHENG SUN, PhD, is Research Assistant Professor in the Department of Electrical and Electronic Engineering at The University of Hong Kong. RUI LI, PhD, is a Research Fellow in the Interconnection and Advanced Packaging Program at Singapore's Institute of Microelectronics. She was the recipient of both the NTU Research and the Ministry of Education Scholarships in Singapore.