Basic Qualification · B-007 Radio wave propagation · B-007-007-011
Quel phénomène de propagation se produit-il lorsqu'une communication VHF est transmise à plus de 800 km?
- ALa réfraction par la couche
- BLa réfraction ionosphérique
- CLa propagation troposphérique guidée (par conduit)
- DLa rotation de Faraday
Correct answer: C — La propagation troposphérique guidée (par conduit). Question tirée de la banque officielle d'ISDE.
Why
Tropospheric ducting occurs when layers of air in the lower atmosphere act like a pipe, trapping VHF signals and guiding them hundreds of kilometres beyond the normal horizon. 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