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Introduction to Rf Propagation

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Introduction to Rf Propagation INTRODUCTION TO RF PROPAGATION John S. Seybold, Ph.D. ,WILEY- 'iNTERSCIENCE JOHN WILEY & SONS, INC. CONTENTS Preface XIII 1. Introduction 1.1 Frequency Designations 1 1.2 Modes of Propagation 3 1.2.1 Line-of-Sight Propagation and the Radio Horizon 3 1.2.2 Non-LOS Propagation 5 1.2.2.1 Indirect or Obstructed Propagation 6 1.2.2.2 Tropospheric Propagation 6 1.2.2.3 Ionospheric Propagation 6 1.2.3 Propagation Effects as a Function of Frequency 9 1.3 Why Model Propagation? 10 1.4 Model Selection and Application 11 1.4.1 Model Sources H 1.5 Summary 12 References 12 Exercises 13 2. Electromagnetics and RF Propagation 14 2.1 Introduction 14 2.2 The Electric Field 14 2.2.1 Permittivity 15 2.2.2 Conductivity 17 2.3 The Magnetic Field 18 2.4 Electromagnetic Waves 20 2.4.1 Electromagnetic Waves in a Perfect Dielectric 22 2.4.2 Electromagnetic Waves in a Lossy Dielectric or Conductor 22 2.4.3 Electromagnetic Waves in a Conductor 22 2.5 Wave Polarization 24 2.6 Propagation of Electromagnetic Waves at Material Boundaries 25 2.6.1 Dielectric to Dielectric Boundary 26 vii VÜi CONTENTS 2.6.2 Dielectric-to-Perfect Conductor Boundaries 31 2.6.3 Dielectric-to-Lossy Dielectric Boundary 31 2.7 Propagation Impairment 32 2.8 Ground Effects on Circular Polarization 33 2.9 Summary 35 References 36 Exercises 36 3. Antenna Fundamentals 38 3.1 Introduction 38 3.2 Antenna Parameters 38 3.2.1 Gain 39 3.2.2 Effective Area 39 3.2.3 Radiation Pattern 42 3.2.4 Polarization 44 3.2.5 Impedance and VSWR 44 3.3 Antenna Radiation Regions 45 3.4 Some Common Antennas 48 3.4.1 The Dipole 48 3.4.2 Beam Antennas 50 3.4.3 Hörn Antennas 52 3.4.4 Reflector Antennas 52 3.4.5 Phased Arrays 54 3.4.6 Other Antennas 54 3.5 Antenna Polarization 55 3.5.1 Cross-Polarization Discrimination 57 3.5.2 Polarization Loss Factor 58 3.6 Antenna Pointing loss 62 3.7 Summary "3 References "4 Exercises "5 4. Communication Systems and the Link Budget 66 4.1 Introduction 66 4.2 Path Loss 67 4.3 Noise 69 4.4 Interference '6 4.5 Detailed Link Budget 79 4.5.1 EIRP 80 4.5.2 Path Loss 80 4.5.3 Receiver Gain 82 4.5.4 Link Margin 83 4.5.5 Signal-to-Noise Ratio 83 CONTENTS ix 4.6 Summary 84 References 85 Exercises 85 5. Radar Systems 87 5.1 Introduction 87 5.2 The Radar Range Equation 88 5.3 Radar Measurements 93 5.3.1 Range Measurement 93 5.3.2 Doppler Measurement 95 5.3.3 Angle Measurement 95 5.3.4 Signature Measurement 98 5.4 Clutter 99 5.4.1 Area Clutter 99 5.4.2 Volume Clutter 105 5.4.3 Clutter Statistics 106 5.5 Atmospheric Impairments 106 5.6 Summary 107 References 108 Exercises 109 6. Atmospheric Effects 111 6.1 Introduction Hl 6.2 Atmospheric Refraction 112 6.2.1 The Radio Horizon 112 6.2.2 Equivalent Earth Radius 113 6.2.3 Ducting 116 6.2.4 Atmospheric Multipath 117 6.3 Atmospheric Attenuation 121 6.4 Loss From Moisture and Precipitation 125 6.4.1 Fog and Clouds 126 6.4.2 Snow and Dust 130 6.5 Summary 131 References 132 Exercises 132 7. Near-Earth Propagation Models 134 7.1 Introduction 134 7.2 Foliage Models 134 7.2.1 Weissberger's Model 135 7.2.2 Early ITU Vegetation Model 135 7.2.3 Updated ITU Vegetation Model 137 [ CONTENTS 7.2.3.1 Terrestrial Path with One Terminal in Woodland 138 7.2.3.2 Single Vegetative Obstruction 138 7.3 Terrain Modeling 141 7.3.1 Egli Model 141 7.3.2 Longley-Rice Model 143 7.3.3 ITU Model 144 7.4 Propagation in Built-Up Areas 146 7.4.1 Young Model 146 7.4.2 Okumura Model 146 7.4.3 Hata Model 151 7.4.4 COST 231 Model 152 7.4.5 Lee Model 153 7.4.6 Comparison of Propagation Models for Built-Up Areas 157 7.5 Summary 159 References 160 Exercises 161 8. Fading and Multipath Characterization 163 8.1 Introduction 163 8.2 Ground-Bounce Multipath 164 8.2.1 Surface Roughness 174 8.2.2 Fresnel Zones 175 8.2.3 Diffraction and Huygen's Principle 179 8.2.4 Quantifying Diffraction Loss 179 8.3 Large-Scale or Log-Normal Fading 186 8.4 Small-Scale Fading 193 8.4.1 Delay Spread 194 8.4.2 Doppler Spread 198 8.4.3 Channel Modeling 199 8.4.4 The Probabilistic Nature of Small-Scale Fading 200 8.5 Summary 203 References 205 Exercises 206 9. Indoor Propagation Modeling 208 9.1 Introduction 208 9.2 Interference 208 9.3 The Indoor Environment 209 9.3.1 Indoor Propagation Effects 209 9.3.2 Indoor Propagation Modeling 210 CONTENTS Xi 9.3.3 The ITU Indoor Path Loss Model 210 9.3.4 The Log-Distance Path Loss Model 214 9.4 Summary 216 References 216 Exercises 216 10. Rain Attenuation of Microwave and Millimeter Wave Signals 218 10.1 Introduction 218 10.2 Link Budget 219 10.3 Rain Fades 222 10.3.1 Specific Attenuation Due to Rainfall 222 10.3.2 The ITU Model 224 10.3.3 The Crane Global Model 229 10.3.4 Other Rain Models 234 10.3.5 Rain Attenuation Model Comparison 234 10.3.6 Slant Paths 234 10.4 The Link Distance Chart 234 10.5 Availability Curves 237 10.6 Other Precipitation 237 10.7 Cross-Polarization Effects 239 10.8 Summary 239 References 240 Exercises 241 Appendix 10A: Data for Rain Attenuation Models 242 11. Satellite Communications 246 11.1 Introduction 246 11.2 Satellite Orbits 247 11.3 Satellite Operating Frequency 249 11.4 Satellite Path Free-Space Loss 249 11.5 Atmospheric Attenuation 252 11.6 Ionospheric Effects 255 11.7 Rain Fades 255 11.7.1 ITU Rain Attenuation Model for Satellite Paths 257 11.7.2 Crane Rain Attenuation Model for Satellite Paths 264 11.7.3 The DAH Rain Attenuation Model 270 11.8 Antenna Considerations 273 11.9 Noise Temperature 274 11.9.1 The Hot-Pad Formula 276 11.9.2 Noise Due to Rain 278 11.9.3 Sun Outages 279 11.10 Summary 279 XÜ CONTENTS References 280 Exercises 281 12. RF Safety 283 12.1 Introduction 283 12.2 Biological Effects of RF Exposure 285 12.3 CC Guidelines 287 12.4 Antenna Considerations 290 12.5 FCC Computations 292 12.5.1 Main Beam and Omnidirectional Antenna Analysis 292 12.5.2 Antenna Directivity 293 12.6 Station Evaluations 297 12.7 Summary 298 References 298 Exercises 299 Appendix A: Review of Probability for Propagation Modeling 301 Index 317 .
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