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Wave Propagation

Wave Propagation. Presented by: Bob Kenyon - K8LJ. CRES Amateur Radio Club 4/22/2008. Agenda. Introduction and background Basic propagation concepts Propagation software overview Modeling program examples Demo of W6ELProp and Ionoscope Open discussion & conclusion. ~ 30 mi.

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Wave Propagation

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  1. Wave Propagation Presented by: Bob Kenyon - K8LJ CRES Amateur Radio Club 4/22/2008

  2. Agenda • Introduction and background • Basic propagation concepts • Propagation software overview • Modeling program examples • Demo of W6ELProp and Ionoscope • Open discussion & conclusion

  3. ~ 30 mi. Primary Propagation Modes • Ground wave • AM BC band daytime; HF across town • Space wave • Point to point (ground not involved) • Sky wave (the focus of this presentation) • Refraction via the ionosphere • Makes world-wide • communications possible • Satellite communications • Artificial propagation (repeater in the sky)

  4. Other Propagation Modes • Back scatter and side scatter • Rain scatter • Tropospheric scatter • Tropospheric ducting • Meteor scatter • Gray line (day - night line) • Aurora • Moon bounce

  5. Some Basic Concepts • Wave Reflection • - Occurs primarily at earth’s surface • Wave Refraction • - Bending that occurs in the ionosphere and elsewhere • Wave Diffraction • - Bending over the earth’s surface or around obstacles

  6. Reflection and Refraction =

  7. . . . . Diffraction Around and Over an Object (Not to scale)

  8. The Earth and Environs (Not to scale) Ionosphere 250 miles 23 miles 6.5 miles Earth Troposphere Stratosphere* * Isothermal region

  9. Layers of the Ionosphere (Not to scale)

  10. Ole Sol (The Sun) A massive nuclear furnace which produces the following: • Visible light (what we can see) • Ultraviolet light (ionizes the F layer) • Soft X-rays (ionizes the E layer) • Hard X-rays (ionizes the D layer - RF sponge) • Solar wind (charged particles that impact the earth’s magnetic field • Solar flares & coronal mass ejections (CMEs) • Sunspots (increases ionization of the F layer)

  11. Optical Window Radio Window The Electromagnetic Spectrum Increasing Wavelength Increasing Frequency

  12. Solar Flare Ionospheric Effects Sun Electromagnetic Radiation Increase Delay 8. 3 min Solar Cosmic Rays Delay 15 min – Several Hours Magnetic Storm Particles Delay 20-40 Hrs High Energy Protons &  Particles Low Energy Protons And Electrons Ultraviolet And X-Rays D-Layer Increase (SWF) D –Layer Increase (PCA) Magnetic Storms Sporadic E D – Layer Increase (Auroral Absorption) Auroras SWF = Short Wave Fading PCA = Polar Cap Absorption

  13. Some Propagation Terms • Critical Frequency The highest frequency returned to earth when transmitted vertically • Critical Angle The highest angle at a given frequency which will be returned to earth • Maximum Useable Frequency (MUF) The highest frequency returned to earth between two specific points • Skip Zone Area between the ground wave end and 1st sky wave reception

  14. Frequency vs. Ionospheric Refraction

  15. Frequency vs. Critical Angle

  16. Critical Angle and the Skip Zone

  17. Close-up View of Actual Sunspot Taken by NSO Sacramento Peak Vacuum Tower Telescope

  18. 100,000 Kilometers

  19. More Propagation Terms • Sunspot number (SN) • - Weighted average of actual sunspots and groups of sunspots • Smoothed sunspot number (SSN) • - SN averaged over + and - 6 months (13 months) • Solar flux • - Measurement of solar radio noise at 2800 MHz. (10.7 cm) • K index (Kp index - planetary) • - A mid latitude geomagnetic index updated every 3 hours (scale 0 - 9) • A index (Ap index - planetary) • - A daily measure derived from the K index (scale 0 - 400)

  20. Some General Principals • Sunspot impact is a long term phenomenon • - Observe months and years, not hours or days • Geomagnetic activity is more short term • - Hours or even minutes can be very important • Use the planetary (Kp and Ap indices) A K Conditions 0 0 Quiet 2 1 Quiet 3 1 Quiet 4 1 Quiet to unsettled 7 2 Unsettled 15 3 Active 27 4 Active 48 5 Minor storm 80 6 Major storm 132 7 Severe storm 208 8 Very major storm 400 9 Very major storm

  21. Guide to Propagation Conditions Using Solar Indices

  22. Smoothed Solar Flux vs. Smoothed Sunspot Number (SSN)

  23. Penticton, B.C. 10.7 cm Solar Flux Monitoring Facility (2800 Mhz)

  24. Smoothed Solar Flux vs. Smoothed Planetary A Index

  25. Last Sunspot Cycle (23)

  26. Comparison of Last Three Solar Cycles (21, 22, & 23)

  27. Pilgrims Land at Plymouth Rock American Revolution 400 Years of Sunspot Observations

  28. Solar Cycle 24 Sunspot Number Prediction

  29. Future Sunspot Cycle Predictions

  30. Propagation Software (Sample) • Public Domain (Free) • W6ELProp V2.7 (demo next) • VOACAP • Commercial • ASAPS V. 4 $275 • HFx V. 1.1 $129 • CAPMan $89 • WinCAP Wizard 2 $29.95 • PropLab Pro $150

  31. Demonstration of W6ELProp V2.7 and Ionoscope

  32. Conclusion

  33. References (1) Davies, K., Ionosopheric Radio, London: Peter Pereginus, 1989. (2) The ARRL Antenna Book, Newington, CT: ARRL, 2002 (3) Jeffrey S. Beasley & Gary M. Miller, Modern Electronic Communication, 9th Edition, Columbus, OH: Prentice Hall, 2008 (4) Jacobs, G., Cohen, T., Rose, R., The NEW Shortwave Propagation Handbook, CQ Communications, Inc., Hicksville, NY: 1995 (5) The ARRL Handbook, Newington, CT: ARRL, 2002 (6) McNamera, L.F., Radio Amateur’s Guide to the Ionosphere, Malabar, FL: Krieger Publishing Co., 1994

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