RADIOWAVE PROPAGATION

Transcription

1 RADIOWAVE PROPAGATION Physics and Applications CURT A. LEVIS JOEL T. JOHNSON FERNANDO L. TEIXEIRA The cover illustration is part of a figure from R.C. Kirby, "Introduction," Lecture 1 in NBS Course in Radio Propagation, Ionospheric Propagation, Central Radio Propagation Laboratory, National Bureau of Standards, U.S. Department of Commerce, Boulder, CO See Figure 1.5 for the original. WILEY A JOHN WILEY & SONS, INC., PUBLICATION

2 CONTENTS Preface xi 1 Introduction Definition of Propagation, Propagation and Systems Design, Historical Perspective, The Influence of Signal Frequency and Environment, Propagation Mechanisms, Summary, Sources of Further Information, Overview of Text, 15 2 Characterization of Propagation Media Introduction, Maxwell's Equations, Boundary Conditions, and Continuity, Constitutive Relations, Dielectric Behavior of Materials: Material Polarization, Material Properties, Simple Media, Magnetic and Conductive Behavior of Materials, Equivalence of Ohmic and Polarization Losses, 30 References, 34 v

3 vi CONTENTS 3 Plane Waves Introduction, D'Alembert's Solution, Pure Traveling Waves, Information Transmission, Sinusoidal Time Dependence in an Ideal Medium, Plane Waves in Lossy and Dispersive Media, Phase and Group Velocity, Wave Polarization, 52 References, 55 4 Antenna and Noise Concepts Introduction, Antenna Concepts, Basic Parameters of Antennas, Receiving Antennas, Noise Considerations, Internal Noise, External Noise, 68 References, 75 5 Direct Transmission Introduction, Friis Transmission Formula, Including Losses in the Friis Formula, Atmospheric Gas Attenuation Effects, Total Attenuation on Horizontal or Vertical Atmospheric Paths, Total Attenuation on Slant Atmospheric Paths, Attenuation at Higher Frequencies and Further Information Sources, Rain Attenuation, Describing Rain, Computing Rain Specific Attenuation, A Simplified Form for Rain Specific Attenuation, Computing the Total Path Attenuation Through Rain, Attenuation Statistics, Frequency Scaling, 97

4 5.4.7 Rain Margin Calculations: An Example, Site Diversity Improvements, Scintillations, 102 Appendix 5.A Look Angles to Geostationary Satellites, 103 References, 105 Reflection and Refraction 6.1 Introduction, Reflection from a Planar Interface: Normal Incidence, Reflection from a Planar Interface: Oblique Incidence, Plane of Incidence, Perpendicular Polarized Fields in Regions 1 and 2, Phase Matching and Snell's Law, Perpendicular Reflection Coefficient, Parallel Polarized Fields in Regions 1 and 2, Parallel Reflection Coefficient, Summary of Reflection Problem, Total Reflection and Critical Angle, Refraction in a Stratified Medium, Refraction Over a Spherical Earth, Refraction in the Earth's Atmosphere, Ducting, Ray-Tracing Methods, 132 References, 134 Terrain Reflection and Diffraction 7.1 Introduction, Propagation Over a Plane Earth, Field Received Along Path Ri: The Direct Ray, Field Received Along Path R 2 : The Reflected Ray, Total Field, Height-Gain Curves, Fresnel Zones, Propagation Over a Plane Earth Revisited in Terms of Fresnel Zones, Earth Curvature and Path Profile Construction, Microwave Link Design, Distance to the Radio Horizon, 149

5 7.5.2 Height-Gain Curves in the Obstructed Region, Height-Gain Curves in the Reflection Region, Path Loss Analysis Examples, Numerical Methods for Path Loss Analysis, Conclusion, 160 References, 160 Empirical Path Loss and Fading Models 8.1 Introduction, Empirical Path Loss Models, Review of the Flat Earth Direct plus Reflected Model, Empirical Model Forms, Okumura-Hata Model, COST-231/Hata Model, Lee Model, Site-General ITU Indoor Model, Other Models for Complex Terrain, An Example of Empirical Path Loss Model Usage, Signal Fading, A Brief Review of Probability Theory, Statistical Characterization of Slow Fading, Statistical Characterization of Narrowband Fast Fading, Example Fading Analyses, Narrowband Fading Mitigation Using Diversity Schemes, Wideband Channels, Coherence Bandwidth and Delay Spread, Coherence Time and Doppler Spread, Conclusion, 187 References, 187 Groundwave Propagation 9.1 Introduction, Planar Earth Groundwave Prediction, Elevated Antennas: Planar Earth Theory, Spherical Earth Groundwave Prediction, Methods for Approximate Calculations, A 1 MHz Sample Calculation, A 10 MHz Sample Calculation, 203

6 9.7 ITU Information and Other Resources, Summary, 205 Appendix 9.A Spherical Earth Groundwave Computations, 211 References, 213 Characteristics of the Ionosphere 10.1 Introduction, The Barometric Law, Chapman's Theory, Introduction, Mathematical Derivation, Structure of the Ionosphere, Variability of the Ionosphere, 229 References, 233 Ionospheric Propagation 11.1 Introduction, Dielectric Properties of an Ionized Medium, Propagation in a Magnetoionic Medium, Mathematical Derivation of the Appleton-Hartree Equation, Physical Interpretation, Ordinary and Extraordinary Waves, The ÖL and ß T Approximations, Ionospheric Propagation Characteristics, Ionospheric Sounding, Ionograms, Examples of Actual Ionograms, The Secant Law, Transmission Curves, Breit and Tuve's Theorem, Martyn's Theorem on Equivalent Virtual Heights, MUF, "Skip" Distance, and Ionospheric Signal Dispersion, Earth Curvature Effects and Ray-Tracing Techniques, Ionospheric Propagation Prediction Tools, Ionospheric Absorption, Ionospheric Effects on Earth-Space Links, Faraday Rotation, Group Delay and Dispersion, 273

7 X CONTENTS Ionospheric Scintillations, Attenuation, Ionospheric Refraction, Monitoring TEC Distribution, 278 References, Other Propagation Mechanisms and Applications Introduction, Tropospheric Scatter, Introduction, Empirical Model for the Median Path Loss, Fading in Troposcatter Links, Meteor Scatter, Tropospheric Delay in Global Satellite Navigation Systems, Propagation Effects on Radar Systems, 291 References, 293 Index 295