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

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

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)

~ 30 mi.

Other Propagation Modes

• Back scatter and side scatter

• Rain scatter

• Tropospheric scatter

• Tropospheric ducting

• Meteor scatter

• Gray line (day - night line)

• Aurora

• Moon bounce

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

Reflection and Refraction

=

Diffraction Around and Over an Object(Not to scale)

..

..

Earth

Ionosphere

Stratosphere*

Troposphere

6.5 miles

23 miles

250 miles

The Earth and Environs

* Isothermal region

(Not to scale)

Layers of the Ionosphere(Not to scale)

Ole Sol (The Sun)

• 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)

A massive nuclear furnace which produces the following:

The Electromagnetic SpectrumIncreasing Wavelength Increasing Frequency

OpticalWindow

RadioWindow

Solar Flare Ionospheric Effects

ElectromagneticRadiation Increase

Delay 8. 3 min

UltravioletAnd X-Rays

D-LayerIncrease (SWF)

Solar Cosmic RaysDelay 15 min – Several

Hours

High Energy Protons & Particles

D –LayerIncrease (PCA)

Magnetic StormParticles

Delay 20-40 Hrs

Low Energy ProtonsAnd Electrons

MagneticStorms

Auroras SporadicE

D – Layer Increase(Auroral Absorption)

Sun

SWF = Short Wave Fading PCA = Polar Cap Absorption

Some Propagation Terms

• Critical Frequency

The highest frequency returned to earth when transmitted vertically

• Critical AngleThe 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 ZoneArea between the ground wave end and 1st sky wave reception

Frequency vs. Ionospheric Refraction

Frequency vs. Critical Angle

Critical Angle and the Skip Zone

Close-up View of Actual Sunspot

Taken by NSO Sacramento Peak Vacuum Tower Telescope

100,000Kilometers

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)

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 Quiet2 1 Quiet3 1 Quiet4 1 Quiet to unsettled7 2 Unsettled15 3 Active27 4 Active48 5 Minor storm80 6 Major storm132 7 Severe storm208 8 Very major storm400 9 Very major storm

Guide to Propagation Conditions Using Solar Indices

Smoothed Solar Flux vs. Smoothed Sunspot Number (SSN)

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

Smoothed Solar Flux vs. Smoothed Planetary A Index

Last Sunspot Cycle (23)

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

400 Years of Sunspot Observations

Pilgrims Landat

Plymouth Rock

AmericanRevolution

Solar Cycle 24 Sunspot Number Prediction

Future Sunspot Cycle Predictions

Propagation Software

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

(Sample)

Demonstration

of

W6ELProp V2.7

and

Ionoscope

Conclusion

(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

References