Broadband Reflectometry for Enhanced Diagnostics and Monitoring Applications (Lecture Notes in Electrical Engineering, 93)

This book is dedicated to the adoption of broadband microwave reflectometry (BMR)-based methods for diagnostics and monitoring applications. This electromagnetic technique has established as a powerful tool for monitoring purposes; in fact, it can balance several contrasting requirements, such as the versatility of the system, low implementation cost, real-time response, possibility of remote control, reliability, and adequate measurement accuracy. Starting from an extensive survey of the state of the art and from a clear and concise overview of the theoretical background, throughout the book, the different approaches of BMR are considered (i.e., time domain reflectometry - TDR, frequency domain reflectometry - FDR, and the TDR/FDR combined approach) and several applications are thoroughly investigated. The applications considered herein are very diverse from each other and cover different fields. In all the described procedures and methods, the ultimate goal is to endow them with a significant performance enhancement in terms of measurement accuracy, low cost, versatility, and practical implementation possibility, so as to unlock the strong potential of BMR. Title 2 Preface 8 Contents 11 Introduction 16 The Concept Behind This Book 16 Survey of Typical Applications of BMR 18 Electrical Components Characterization: Testing and Localization of Faults 18 Measurements on Soil for Agricultural and Geotechnical Purposes 19 Civil Engineering and Infrastructural Monitoring 19 Dielectric Spectroscopy Measurements 20 Applications in Industrial Monitoring 20 Organization and Content of the Book 20 References 22 Basic Physical Principles 25 Transmission Line Basics 25 Coaxial Transmission Line 26 Bifilar Transmission Line 28 Microstrip Line 28 Reflected Waves 29 Characteristic Parameters of Electrical Networks 30 Reflectometry Measurements for Dielectric Spectroscopy 33 Dielectric Relaxation Models 34 References 37 Broadband Reflectometry: Theoretical Background 39 Broadband Microwave Reflectometry: Theoretical Background 39 Time Domain Reflectometry (TDR) 40 Typical TDR Measurements 43 Typical TDR Instrumentation 44 Frequency Domain Reflectometry (FDR) 47 TD/FD Combined Approach 49 Preserving Measurement Accuracy in the TDR/FDR Transformation 50 The Sensing Element 51 Strategies for Enhancing Accuracy in BMR Measurements 55 Calibration Procedure in Time Domain 55 Calibration Procedure in Frequency Domain 56 Time-gated Frequency Domain Approach 57 Transmission Line Modeling and Inverse Modeling 58 References 61 Quantitative and Qualitative Characterization of Liquid Materials 64 Introduction 64 Estimation of Levels and Permittivities of Industrial Liquids Directly from TDR 66 Probe Design and Realization 67 Sources of Errors and Compensation Strategies in TD 69 Validation of the Method on Dielectric Liquids 71 Estimation of Levels and Permittivities of Industrial Liquids 73 Transmission Line Modeling of the Measurement Cell 74 Measurement Setup and Enhanced Probe Design 75 Experimental Validation of the Method 77 Dielectric Spectroscopy of Edible Liquids: The Vegetable Oils Case-Study 84 Design of the Measurement Cell and Transmission Line Modeling 85 Experimental Results for Vegetable Oils 90 References 95 Qualitative Characterization of Granular Materials and Moisture Measurements 97 Introduction 97 Dielectric Models for the Estimation of Water Content 99 Evaluation of Moisture Content Directly from TDR 101 Details on the Experimental Procedure 102 Uncertainty Evaluation for Apparent Dielectric Permittivity Measurement and Individuation of the Calibration Curves 103 Measurement Results and Instrumental Performance Comparison 105 Moisture Content Measurements through TD/FD Combined Approach 109 Moisture Content Measurements through Dielectric Mixing Model 109 Triple-Short Calibration Procedure 110 Enhancements of TDR-Based Static Electrical Conductivity Measurement 119 Traditional TDR-Based Static Electrical Conductivity Measurement 120 Innovative Calibration Strategies: The TLM and the ICM Methods 122 Validation of the Methods 127 Practical Considerations 131 Noninvasive Moisture Content Measurements 131 Basic Theory of Microstrip Antennas 132 Experimental Validation of the Method: Measurements on Moistened Sand Samples 134 References 140 BMR Characterization of Antennas through the Combined TD/FD Approach 144 Introduction 144 Measurement Setup for the Validation of the Method 145 Acquisition in Time Domain 146 RFId Antenna Results 148 Practical Guidelines for Retrieving Accurate Measurements 149 Biconical Antenna Results 156 References 158 This book examines the adoption of broadband microwave reflectometry (BMR)-based methods for diagnostics and monitoring applications. It details the different approaches of BMR and investigates major practical applications.