Basic Qualification · B-007 Radio wave propagation · B-007-001-003
When a signal is returned to Earth by the ionosphere, what is this called?
- A Sky-wave propagation
- B Tropospheric propagation
- C Ground-wave propagation
- D Earth-Moon-Earth propagation
Correct answer: A — Sky-wave propagation. From the official ISED question bank, verified word for word.
Why
When a radio signal bounces off the ionosphere, a layer of charged particles high in the atmosphere, and returns to Earth, it is called Sky-wave propagation. 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.