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 Antennas 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