Transcript Wave Propagation - The CRES Amateur Radio Club Secretary`s

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)
~ 30 mi.
•
Sky wave (the focus of this presentation)
- Refraction via the ionosphere
- Makes world-wide
communications possible
• Satellite communications
- Artificial propagation (repeater in the sky)
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)
..
..
The Earth and Environs
(Not to scale)
Ionosphere
250 miles
23 miles
6.5 miles
Earth
Troposphere
Stratosphere*
* Isothermal region
Layers of the Ionosphere
(Not to scale)
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)
The Electromagnetic Spectrum
Increasing Wavelength
Increasing Frequency
Optical
Window
Radio
Window
Solar Flare Ionospheric Effects
Sun
Electromagnetic
Radiation Increase
Delay 8. 3 min
Solar Cosmic Rays
Delay 15 min – Several
Hours
Ultraviolet
And X-Rays
High Energy Protons
&  Particles
D-Layer
Increase (SWF)
D –Layer
Increase (PCA)
SWF = Short Wave Fading
PCA = Polar Cap Absorption
Magnetic Storm
Particles
Delay 20-40 Hrs
Low Energy Protons
And Electrons
Magnetic
Storms
Auroras
Sporadic
E
D – Layer Increase
(Auroral Absorption)
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
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
100,000
Kilometers
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
2
3
4
7
15
27
48
80
132
208
400
0
1
1
1
2
3
4
5
6
7
8
9
Quiet
Quiet
Quiet
Quiet to unsettled
Unsettled
Active
Active
Minor storm
Major storm
Severe storm
Very major storm
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 Land
at
Plymouth Rock
American
Revolution
Solar Cycle 24 Sunspot Number Prediction
Future Sunspot Cycle Predictions
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
Demonstration
of
W6ELProp V2.7
and
Ionoscope
Conclusion
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