HF Propagation Lab
Student Exercises
Use these tasks with the live lab page. Predict first, then check the
band cards, beacons, skimmers, WSPR or PSKReporter, and your receiver. Explain the difference between your prediction, the model, and what operators are actually hearing.
Back to lab
Write predictions before checking
Use UTC, station grid, and real signals 1. Pick a DX Band
Set your station grid and a DX station in Europe, around 5000-7000 km
away. Given the current SFI, Kp, and local solar time, choose one band
for a first call and one backup band. Explain why.
Check your reasoning
Look for whether the estimated MUF is above your chosen band,
whether FOT is closer to a lower band, and whether Kp makes the path
unreliable.
2. Find the Skip Zone
Choose a destination 600-1000 km from your station and compare it with
one 2500-3500 km away. Which one is more likely to be loud on 20m
right now? Which one might need a lower band, high-angle radiation, or NVIS-style operation instead?
Check your reasoning
If a nearby station is inside the skip zone on a higher band, a
lower band with higher-angle radiation may be better even when the
higher band has a good DX score. Do not assume 40m NVIS reaches every 600-1000 km path; compare 80m, 60m where legal, 40m, antenna height, and current absorption.
3. Flare Watch
If the lab reports an M- or X-class flare, predict which side of Earth
is affected and which bands should suffer first. Then check the alert
panel and X-ray metric card.
Check your reasoning
Short-wave fadeouts primarily affect the sunlit side. Lower HF
usually feels the enhanced D-layer absorption first, but strong
events can weaken much of HF.
4. Grey-Line Test
Run the lab within an hour of your sunrise or sunset. Which low band
gets a grey-line boost? Would you call that a DX opportunity, an NVIS
opportunity, or both?
Check your reasoning
Grey-line enhancement is strongest when D-layer absorption is
collapsing but useful F-layer ionization remains. It is especially
interesting on 160m, 80m, and 40m.
5. Explain Reciprocity
If the path from your station to the DX station is open, explain why
the reverse path is normally open too. Then list two local factors
that can still make one operator hear better than the other.
Examples of local factors: antenna pattern, noise floor, power,
terrain, polarization, and receiver performance.