Basic Qualification · B-007 Radio wave propagation · B-007-002-004
Quelle couche ionosphérique est la moins utile pour les communications à longues distances par ondes radio?
- ALa couche E
- BLa couche
- CLa couche F2
- DLa couche F1
Correct answer: B — La couche. Question tirée de la banque officielle d'ISDE.
Why
The D region sits lowest in the ionosphere and acts like a sponge that absorbs radio signals rather than bouncing them back to Earth, making it useless for long-distance communication. The full explanation — and one for every question — is in Pro.
Practise this section
Radio wave propagation is section B-007 of the Basic exam: How signals travel: the ionosphere and its layers, skip, ground wave, sporadic E, and which bands work when.
Drill B-007 — free, no account