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2 Graham Brodie, Mohan V. Jacob, Peter Farrell Microwave and Radio-Frequency Technologies in Agriculture An Introduction for Agriculturalists and Engineers

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4 Graham Brodie, Mohan V. Jacob, Peter Farrell Microwave and Radio-Frequency Technologies in Agriculture An Introduction for Agriculturalists and Engineers Managing Editor: Magdalena Golachowska

5 Published by De Gruyter Open Ltd, Warsaw/Berlin Part of Walter de Gruyter GmbH, Berlin/Munich/Boston This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivs 3.0 license, which means that the text may be used for non-commercial purposes, provided credit is given to the author. For details go to Copyright 2015 Graham Brodie, Mohan V. Jacob, Peter Farrell ISBN e- ISBN Bibliographic information published by the Deutsche Nationalbibliothek. The Deutsche Nationalbibliothek lists this publication in the Deutsche Nationalbibliografie; detailed bibliographic data are available in the Internet at Managing Editor: Magdalena Golachowska Cover illustration: Graham Brodie

6 Contents Preface VII Section 1: General Introduction 1 Introduction 1 References 5 2 Some Brief Examples of Technical Innovation in Agricultural Industries Machines Early Innovations in Agriculture Transportation Technologies The Tractor The Green Revolution High Resolution Production Systems Spatial Data Temporal Data Conclusions 16 References 17 3 A Brief Overview of Radio Frequency and Microwave Applications in Agriculture Heating Applications Crop Drying Quarantine Effect of Microwave Heating on Seeds and Plants Microwave Treatment of Animal Fodder Microwave Assisted Extraction Microwave Assisted Pyrolysis and Bio-fuel Extraction Sensor Applications Assessment of Wood Radar Systems Communication Systems Conclusion 28 References 28 4 Microwaves and their Interactions with Materials Electric and Magnetic Field Vectors Maxwell s Equations for Electro-magnetism Magnetic Vector Potential 37

7 4.4 Continuity Conservation of Electromagnetic Energy Boundary Conditions Wave Impedance Reflection and Transmission at an Interface Electromagnetic Behaviour of Materials Conclusions 47 References 48 Section 2: Non-destructive Characterisation Using Electromagnetic Waves 5 Section Introduction 50 References 50 6 Techniques for Measuring Dielectric Properties Dielectric Properties Polarization DIPOLAR POLARIZATION IONIC POLARIZATION ELECTRONIC AND ATOMIC POLARIZATION INTERFACIAL OR SPACE CHARGE POLARIZATION DIELECTRIC LOSS RELAXATION TIME Cole-Cole diagram Bode plots and Nyquist Plots Microwave Measurement Methods Transmission/Reflection Line Method Resonant Technique Dielectric Resonator Dielectric Post Resonator Whispering Gallery Mode Resonator Open-ended co-axial probe method Dielectric Probe (Coaxial probe) Free Space Method Antenna Near-field Microwave Probe Reentrant Cavity Fabry-Perot Resonator Conclusions 72 References 75

8 7 Dielectric Properties of Organic Materials Frequency Dependency of Dielectric Properties Temperature Dependence of the Dielectric Properties Density and Field Orientation Dependence of Dielectric Properties Dielectric Modelling of Organic Materials Modelling the Dielectric Properties of Free Water Modelling the Dielectric Properties of Bound Water Modelling the Dielectric Properties of Moist Wood Modelling the Dielectric Properties of Grains Modelling the Dielectric Properties of Soils Dielectric Properties of Insects Conclusions 96 References 96 8 Insect and Decay Detection Radar Entomology Antennas Rectangular Apertures Open Ended Wave-Guide Horn Antennas Circular Apertures Antenna Gain Radar Range Radar Cross Section Close Range Radar Motion Detection - Doppler Shift Free-Space Microwave Systems Decay Detection Conclusions 120 References Moisture Monitoring Free-Space Moisture Detection Practical Applications Microwave Emissions as a Measure of Moisture Radar Moisture Measurement 128 References Radar Imaging Radar Imaging Image Distortion Target Interaction and Image Appearance Airborne versus Space-borne Radar 136

9 10.5 Ground Penetrating Radar 137 References Electromagnetic Survey Techniques Electromagnetic Induction EM EM EM EM Global Positioning System Principles of GPS Operation Step 1: Triangulating from Satellites Step 2: Measuring distance from a satellite Step 3: Getting perfect timing Step 4: Knowing where a satellite is in space Step 5: Correcting errors Differential GPS Geographic Information Systems Integration Limitations 149 References 150 Section 3: Dialectric Heating 12 Section Introduction 152 References Dielectric Heating Conductive Heat Transfer Convective Heating Radiative Heat Transfer Microwave Heating Microwave Frequency and its Influence over Microwave Heating The Influence of Material Geometry on Microwave Heating Comparative Efficiency of Convective and Microwave Heating Thermal Runaway Examples of Using Thermal Runaway to Great Advantage Conclusion 171 Nomenclature 171 References 173

10 14 Simultaneous Heat and Moisture Movement Temperature Sensing in Electromagnetic Fields 179 References Microwave Drying Microwave Drying of Crop Fodder Modelling Microwave Drying Effect of Microwave Drying on Milling Properties 186 References Radio Frequency and Microwave Processing of Food Dielectric Properties of Foods Comparative Efficiency of Convective and Microwave Heating 192 References Microwave Applicators Wave-Guides Waveguide Modes Other Wave-guide Modes Transverse Magnetic Modes Wave-guide Cut-off Conditions Wavelength in a Wave-guide Wave Impedance in a Wave-guide Power Flow along a Wave-guide Propagating in TE10 Mode Cylindrical Wave Guides Microwave Ovens Finite-Difference Time-Domain (FDTD) Simulating Microwave Field Distributions in Applicators Microwave Safety Antenna Applicators Analysis of a Horn Antenna A Uniformly Illuminated Aperture Approximation A Numerical Integration Approximation Other Options 213 Nomenclature 214 Appendix A Derivation of Near Field from a Uniformly Illuminated Rectangular Aperture 216 References Quarantine and Biosecurity Insect Control The Background to Microwave and Radiofrequency Quarantine 220

11 Termites as a Case Study Microbial Control Conclusions 224 References Weed Management Radio Frequency and Microwave Treatments Microwave Treatment of Plants Reinterpretation of Earlier Microwave Weed Experiments Impact of Microwave Treatment on Soil Crop Growth Response Analysis of Potential Crop Yield Response to Microwave Weed Management The Potential for Including Microwave Weed Control for Herbicide Resistance Management Conclusion Nomenclature 243 Appendix A Derivation of the Impact of Weed Infestation and Herbicide Control on Crop Yield Response 245 References Treatment of Animal Fodder Effect of Microwave Treatment on Digestibility Microstructure Changes Potential Mitigation of Methane Production Microwave Treatment of Grains Effect of Microwave Heating on Crude Protein Conclusion 266 References Wood Modification Applications of Microwave Modification in Wood Drying Improving Wood Impregnation Stress Relief Industrial Scale Pilot Plant Pre-treatment for Wood Pulping 277 References Microwave Assisted Extraction Solvent based Extraction of Essential Oils Solvent Free Extraction of Essential Oils Microwave Pre-treatment Followed by Conventional Extraction Techniques 282

12 22.4 Application to Sugar Juice Extraction Microwave Accelerated Steam Distillation 283 References Thermal Processing of Biomass BioSolids Biosolids Composition and Characteristics Nutrient Value of Biosolids Current Applications of Biosolids Thermal Processing of Materials Combustion Gasification Anaerobic Decomposition (Torrefaction and Pyrolysis) Microwave-assisted Pyrolysis Biochar 294 References 295 Section 4: Automatic Data Acquisition and Wireless Sensor Networks 24 Section Introduction 300 References Data Acquisition Sensors / Transducers Power Supply Accuracy and Its Components Transducer Output Signal Conditioning Noise Amplification Offset Adjustment Digital Data Acquisition Sample and Hold Circuits Aliasing Multiplexing Analogue-to-Digital Conversion Software Lightning Protection Some Notes on Earthing Systems 318 References 320

13 26 Radio Frequency and Microwave Communication Systems Principles of RF and Microwave Communication Principles of Wireless Communication Modulation Simplex, Half-duplex and Duplex Communication Systems Digital Communication Transmission Channels Transmission Lines Loss-Less Transmission Line Lossy Transmission Line Optic Fibre Wireless Radio Channels 334 References Wireless Ad Hoc Sensor Networks Network Configurations Open Source Platforms Raspberry Pi Arduino Mobile Telephone Networks Power Supply Available Solar Energy 340 References RFID Systems Active, Semi-passive and Passive RFID Tags Animal Tracking Systems Environmental Sensor Applications Near Field Communication 348 References Conclusions Heating Applications Sensor Applications Communication Systems Conclusion 353 References 353

14 Preface Modern agriculture is the foundation of society and culture. Without adequate supplies of food and fibre, society has insufficient energy to do more than simply survive. Humanity s ability to produce enough food to sustain its current population is mostly due to adoption of new methods and technologies by the agricultural industries as they became available. Mechanisation transformed agricultural practices. In this modern era, new information, communication and high speed processing technologies have the potential to further transform the industry. Many of these technologies incorporate radio-frequency and microwave radiation into their systems. This book presents an overview of some ways these parts of the electromagnetic spectrum are being used in agricultural systems. The book does not attempt to present every possible application because this field of study is progressing very rapidly. Neither does it attempt to explore every detail of the technologies. The main purposes of the book is provide a glimpse of what is possible and encourage practitioners in the engineering and agricultural industries to explore how radio-frequency and microwave systems might further enhance the agricultural industry.