Mapleham Study — Chapter 7

Chapter 7 — Key Takeaways

Ground Wave — follows Earth surface, best on low HF, limited range. Sky wave refracted by ionosphere for DX. Line of sight primary on VHF and above
Ionosphere Layers — D absorbs day only, E occasional 6 metre skip, F1 and F2 for HF DX, F2 most important
Skip Zone — dead zone between ground wave limit and sky wave first return point. Lower radiation angle produces longer skip distance.
MUF and LUF — MUF is highest frequency returning to Earth, LUF is lowest usable before D-layer absorption, listen for signals to check MUF
D Layer and Fading — D layer absorbs lower HF by day, fading from multi-path, SID from solar flare shuts down HF for minutes to hours
Sunspots and Solar Cycle — sunspots increase solar radiation, raise MUF, improve HF. 11-year cycle with solar max opening high bands
Sporadic-E and Tropospheric Ducting — Es provides VHF skip on 6 metres, tropospheric ducting extends VHF and UHF range
Scatter Propagation — weak signals heard in skip zone, works above MUF, includes auroral scatter on VHF with distorted signal