Introduction to Radiosport: Understanding Propagation
Leonard Kay, K1NU
A (very) Short Course in HF Propagation for Contesters
• Propagation: What’s important– Why do we care?– What data do we need,
and how do we get it?– How do we use it?
• Tools to help you
Sample: MOFWIN map – 26 October, 2000Z, SF=150
Propagation: Why do we care?
• Bottom line: We want to:– Maximize rate (primary, strong paths)– Maximize multipliers (weaker primary and secondary
paths)– Have fun (maybe work some new band-countries!)
• Propagation conditions determine band openings– What band(s)– When– To where– Quality of openings (signal strength, arrival angles)
• All stations being equal, we win by exploiting more openings
• Important for both SO and MO
Propagation:Where does the data come from?
• Predictive Software– Based on empirical and theoretical models– Inputs
• time & date• QTH• solar parameters (flux/SSN, A index, K index)• frequencies
– Output• path openings as function of time and freq
• Empirical– experience and Conventional Wisdom– HFTA - arrival angle files
Propagation: How do we use it?
• Operating strategy– Know your band openings
• ‘General’ openings for your QTH– EU: morning – high bands
• Specific details per time of year, contest (DX/local), and solar cycle
– 15m to EU: open at 1000Z or 1300Z?
– Plan your operating time accordingly
• Optimize your antennas– Best use of takeoff angle
The Sun
• 11-year sunspot cycle• 27-day rotation period• Daily parameters
– Solar flux, A index, K index– From WWV [SH/WWV on packet]– web site
Quick review – skywave propagation
More to scale...
The signal loses strength on each hop
Lower takeoff angle means fewer hops = stronger signal
Signal Arrival Angles and Your Antennas
• DX– Typically low: 0° – 30°– Need high yagis (at least /2, pref.)
or verticals (gain a plus)
• Local– Typically higher: 20° - 90°– Lower dipoles or other horiz-polarized
antennas
• An antenna can be too high
Software!
Program Before During
Geoclock (shareware)www.geoclock.com
W6EL Prop (free)www.qsl.net/w6elprop
K1TTT MOFWIN (free)www.k1ttt.net/software.html
HFTA (comes with Antenna Book)ARRL Antenna Book CD
Geoclock – world map
Geoclock – US Map
Geoclock – Great Circle map
W6EL Prop
• Windows version of DOS MINIPROP
• Models D, E, and F layers• Text based• Other useful utilities
– Great circle map– Frequency map (similar to
MOFWIN)
W6EL input
W6EL output
K1TTT MOFWIN
• Geoclock and W6EL rolled into one• Input screen
MOFWIN out – 26.10, 0900Z, SF=150
MOFWIN out – 26.10, 2000Z, SF=150
What does it all mean?
• Strategy– Know your band openings and plan around them
• Primary paths for rate• Hunt for multipliers on other paths
– Use software before and during the contest• Fine-tune your strategy and identify openings• Real-time monitors
• Antennas– DX:
• Get your yagis as high as possible• Put up verticals
– Local:• Low dipoles and other high-angle radiators