Basic Qualification · B-007 Radio wave propagation · B-007-008-001
What kind of unusual HF propagation allows weak signals from the skip zone to be heard?
- A Ducting
- B Ground wave
- C Scatter-mode
- D Sky-wave with low radiation angle
Correct answer: C — Scatter-mode. From the official ISED question bank, verified word for word.
Why
Scatter-mode happens when a small part of your sky-wave signal bounces off irregularities in the upper atmosphere, sending a weak, scattered signal into the skip zone where normal sky-waves do not reach. The full explanation — and one for every question — is in Pro.
Practise this section
How signals travel: the ionosphere and its layers, skip, ground wave, sporadic E, and which bands work when.