INTRODUCTION TO RF PROPAGATION

Transcription

1 INTRODUCTION TO RF PROPAGATION John S. Seybold, Ph.D.,WILEY- 'interscience JOHN WILEY & SONS, INC.

2 Preface XIII 1. Introduction 1.1 Frequency Designations Modes of Propagation Line-of-Sight Propagation and the Radio Horizon Non-LOS Propagation Indirect or Obstructed Propagation Tropospheric Propagation Ionospheric Propagation Propagation Effects as a Function of Frequency Why Model Propagation? Model Selection and Application Model Sources H 1.5 Summary 12 References 12 Exercises Electromagnetics and RF Propagation Introduction The Electric Field Permittivity Conductivity The Magnetic Field Electromagnetic Waves Electromagnetic Waves in a Perfect Dielectric Electromagnetic Waves in a Lossy Dielectric or Conductor Electromagnetic Waves in a Conductor Wave Polarization Propagation of Electromagnetic Waves at Material Boundaries Dielectric to Dielectric Boundary 26 vii

3 VÜi Dielectric-to-Perfect Conductor Boundaries Dielectric-to-Lossy Dielectric Boundary Propagation Impairment Ground Effects on Circular Polarization Summary 35 References 36 Exercises Antenna Fundamentals Introduction Antenna Parameters Gain Effective Area Radiation Pattern Polarization Impedance and VSWR Antenna Radiation Regions Some Common Antennas The Dipole Beam Antennas Hörn Antennas Reflector Antennas Phased Arrays Other Antennas Antenna Polarization Cross-Polarization Discrimination Polarization Loss Factor Antenna Pointing loss Summary "3 References "4 Exercises "5 4. Communication Systems and the Link Budget Introduction Path Loss Noise Interference '6 4.5 Detailed Link Budget EIRP Path Loss Receiver Gain Link Margin Signal-to-Noise Ratio 83

4 ix 4.6 Summary 84 References 85 Exercises Radar Systems Introduction The Radar Range Equation Radar Measurements Range Measurement Doppler Measurement Angle Measurement Signature Measurement Clutter Area Clutter Volume Clutter Clutter Statistics Atmospheric Impairments Summary 107 References 108 Exercises Atmospheric Effects Introduction Hl 6.2 Atmospheric Refraction The Radio Horizon Equivalent Earth Radius Ducting Atmospheric Multipath Atmospheric Attenuation Loss From Moisture and Precipitation Fog and Clouds Snow and Dust Summary 131 References 132 Exercises Near-Earth Propagation Models Introduction Foliage Models Weissberger's Model Early ITU Vegetation Model Updated ITU Vegetation Model 137

5 [ Terrestrial Path with One Terminal in Woodland Single Vegetative Obstruction Terrain Modeling Egli Model Longley-Rice Model ITU Model Propagation in Built-Up Areas Young Model Okumura Model Hata Model COST 231 Model Lee Model Comparison of Propagation Models for Built-Up Areas Summary 159 References 160 Exercises Fading and Multipath Characterization Introduction Ground-Bounce Multipath Surface Roughness Fresnel Zones Diffraction and Huygen's Principle Quantifying Diffraction Loss Large-Scale or Log-Normal Fading Small-Scale Fading Delay Spread Doppler Spread Channel Modeling The Probabilistic Nature of Small-Scale Fading Summary 203 References 205 Exercises Indoor Propagation Modeling Introduction Interference The Indoor Environment Indoor Propagation Effects Indoor Propagation Modeling 210

6 Xi The ITU Indoor Path Loss Model The Log-Distance Path Loss Model Summary 216 References 216 Exercises Rain Attenuation of Microwave and Millimeter Wave Signals Introduction Link Budget Rain Fades Specific Attenuation Due to Rainfall The ITU Model The Crane Global Model Other Rain Models Rain Attenuation Model Comparison Slant Paths The Link Distance Chart Availability Curves Other Precipitation Cross-Polarization Effects Summary 239 References 240 Exercises 241 Appendix 10A: Data for Rain Attenuation Models Satellite Communications Introduction Satellite Orbits Satellite Operating Frequency Satellite Path Free-Space Loss Atmospheric Attenuation Ionospheric Effects Rain Fades ITU Rain Attenuation Model for Satellite Paths Crane Rain Attenuation Model for Satellite Paths The DAH Rain Attenuation Model Antenna Considerations Noise Temperature The Hot-Pad Formula Noise Due to Rain Sun Outages Summary 279

7 XÜ References 280 Exercises RF Safety Introduction Biological Effects of RF Exposure CC Guidelines Antenna Considerations FCC Computations Main Beam and Omnidirectional Antenna Analysis Antenna Directivity Station Evaluations Summary 298 References 298 Exercises 299 Appendix A: Review of Probability for Propagation Modeling 301 Index 317