Basic Qualification · B-007 Radio wave propagation · B-007-008-011
Dans quelle gamme de fréquences, la propagation par diffusion météorique est-elle la plus efficace lors de communications à grandes distances?
- ADe 3 MHz à 10 MHz
- BDe 100 MHz à 150 MHz
- CDe 30 MHz à 100 MHz
- DDe 10 MHz à 30 MHz
Correct answer: C — De 30 MHz à 100 MHz. Question tirée de la banque officielle d'ISDE.
Why
Meteor scatter works best between 30 MHz and 100 MHz because the ionized trails left by burning meteors are dense enough to reflect these higher frequencies back to Earth, enabling communication over hundreds of kilometres. 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