Basic Qualification · B-007 Radio wave propagation · B-007-001-010
La réception de signaux radio haute fréquence (HF) au-delà de 4000 km est généralement rendue possible par:
- Al'onde de sol
- Bl'onde diffusée
- Cl'onde d'espace
- Dl'onde ionosphérique
Correct answer: D — l'onde ionosphérique. Question tirée de la banque officielle d'ISDE.
Why
High frequency radio waves travel thousands of kilometres by bouncing off the ionosphere, a charged layer high in the atmosphere that acts like a mirror for these signals. 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