Grounding and Shielding

A Historical Perspective into Grounding and Shielding xv

1. Voltage and Capacitors 1

1.1. Introduction 1

1.2. Charges and Electrons 4

1.3. The Electric Force Field 6

1.4. Field Representations 6

1.5. The Definition of Voltage 9

1.6. Equipotential Surfaces 10

1.7. The Force Field or E Field Between Two Conducting Plates 11

1.8. Electric Field Patterns 12

1.9. The Energy Stored in An Electric Field 16

1.10. Dielectrics 17

1.11. The D Field 18

1.12. Capacitance 19

1.13. Mutual Capacitance 21

1.14. Displacement Current 22

1.15. Energy Stored in a Capacitor 23

1.16. Forces in the Electric Field 24

1.17. Capacitors 25

1.18. Dielectric Absorption 25

1.19. Resistance of Plane Conductors 26

2. Magnetics 27

2.1. Magnetic Fields 27

2.2. Ampere's Law 29

2.3. The Solenoid 30

2.4. Faraday's Law and the Induction Field 30

2.5. The Definition of Inductance 32

2.6. The Energy Stored in an Inductance 32

2.7. Magnetic Field Energy in Space 34

2.8. Electron Drift 36

2.9. The Magnetic Circuit 36

2.10. A Magnetic Circuit with a Gap 38

2.11. Small Inductors 39

2.12. Self- and Mutual Inductance 40

2.13. Transformer Action 40

2.14. Hysteresis and Permeability 45

2.15. Eddy Currents 46

3. Digital Electronics 48

3.1. Introduction 49

3.2. The Transport of Electrical Energy 49

3.3. Transmission Lines-Introduction 50

3.4. Transmission Line Operations 52

3.5. Transmission Line Field Patterns 54

3.6. A Terminated Transmission Line 54

3.7. The Unterminated Transmission Line 56

3.8. A Short Circuit Termination 58

3.9. The Real World 59

3.10. SineWaves Versus Step Voltages 60

3.11. A Bit of History 61

3.12. Ideal Conditions 61

3.13. Reflection and Transmission Coefficients 62

3.14. Taking Energy from an Ideal Energy Source 63

3.15. A Capacitor as a Transmission Line 63

3.16. Decoupling Capacitors and Natural Frequencies 65

3.17. Printed Circuit Boards 66

3.18. Two-Layer Logic Boards 67

3.19. Vias 68

3.20. The Termination of Transmission Lines 70

3.21. Energy in the Ground/Power Plane Capacitance 72

3.22. Poynting's Vector 73

3.23. Skin Effect 74

3.24. Measurement Problems: Ground Bounce 75

3.25. Balanced Transmission 76

3.26. Ribbon Cable and Connectors 77

3.27. Interfacing Analog and Digital Circuits 78

4. Analog Circuits 80

4.1. Introduction 80

4.2. Instrumentation 81

4.3. History 83

4.4. The Basic Shield Enclosure 83

4.5. The Enclosure and Utility Power 86

4.6. The Two-Ground Problem 88

4.7. Instrumentation and the Two-Ground Problem 89

4.8. Strain-Gauge Instrumentation 92

4.9. The Floating Strain Gauge 93

4.10. The Thermocouple 95

4.11. The Basic Low-Gain Differential Amplifier (Forward Referencing Amplifer) 96

4.12. Shielding in Power Transformers 98

4.13. Calibration and Interference 99

4.14. The Guard Shield Above 100 kHz 100

4.15. Signal Flow Paths in Analog Circuits 101

4.16. Parallel Active Components 101

4.17. Feedback Stability-Introduction 102

4.18. Feedback Theory 103

4.19. Output Loads and Circuit Stability 105

4.20. Feedback Around a Power Stage 105

4.21. Constant Current Loops 106

4.22. Filters and Aliasing Errors 107

4.23. Isolation and DC-To-DC Converters 108

4.24. Charge Converter Basics 110

4.25. DC Power Supplies 113

4.26. Guard Rings 113

4.27. Thermocouple Effects 114

4.28. Some Thoughts on Instrumentation 114

5. Utility Power and Facility Grounding 115

5.1. Introduction 115

5.2. History 116

5.3. Semantics 116

5.4. Utility Power 117

5.5. The Earth as a Conductor 119

5.6. The Neutral Connection to Earth 120

5.7. Ground Potential Differences 122

5.8. Field Coupling to Power Conductors 124

5.9. Neutral Conductors 125

5.10. k Factor in Transformers 126

5.11. Power Factor Correction 127

5.12. Ungrounded Power 127

5.13. A Request for Power 128

5.14. Earth Power Currents 129

5.15. Line Filters 129

5.16. Isolated Grounds 130

5.17. Facility Grounds-Some More History 132

5.18. Ground Planes in Facilities 134

5.19. Other Ground Planes 137

5.20. Ground at Remote Sites 137

5.21. Extending Ground Planes 137

5.22. Lightning 138

5.23. Lightning and Facilities 139

5.24. Lightning Protection for Boats and Ships 141

5.25. Grounding of Boats and Ships at Dock 143

5.26. Aircraft Grounding (Fueling) 144

5.27. Ground Fault Interruption (GFI) 144

5.28. Isolation Transformers 145

5.29. Grounding and the Pacific Intertie 147

5.30. SolarWind 148

6. Radiation 149

6.1. Handling Radiation and Susceptibility 149

6.2. Radiation 150

6.3. SineWaves and Transmission Lines 151

6.4. Approximations for Pulses and SquareWaves 152

6.5. Radiation from Components 156

6.6. The Dipole Antenna 157

6.7. Wave Impedance 158

6.8. Field Strength and Antenna Gain 159

6.9. Radiation from Loops 160

6.10. E-Field Coupling to a Loop 162

6.11. Radiation from Printed Circuit Boards 163

6.12. The Sniffer and the Antenna 164

6.13. Microwave Ovens 165

7. Shielding from Radiation 166

7.1. Cables with Shields 166

7.2. Low-Noise Cables 168

7.3. Transfer Impedance 169

7.4. Waveguides 172

7.5. Electromagnetic Fields over a Ground Plane 173

7.6. Fields and Conductors 174

7.7. Conductive Enclosures-Introduction 175

7.8. Coupling Through EnclosureWalls by an Induction Field 176

7.9. Reflection and Absorption of Field Energy at a Conducting Surface 177

7.10. Independent Apertures 178

7.11. Dependent Apertures 179

7.12. Honeycombs 180

7.13. Summing Field Penetrations 181

7.14. Power Line Filters 182

7.15. Backshell Connectors 184

7.16. H-Field Coupling 186

7.17. Gaskets 186

7.18. Finger Stock 187

7.19. Glass Apertures 188

7.20. Guarding Large Transistors 188

7.21. Mounting Components on Surfaces 188

7.22. Zappers 190

7.23. Shielded and Screen Rooms 190

AppendixA. The Decibel 192

Further Reading 194

Index 195