Basic Qualification · B-007 Radio wave propagation · B-007-006-011
L'été, durant le jour, sur quelles bandes les communications sont-elles les plus difficiles au-delà des ondes de sol?
- A160 mètres et 80 mètres
- B40 mètres
- C30 mètres
- D20 mètres
Correct answer: A — 160 mètres et 80 mètres. Question tirée de la banque officielle d'ISDE.
Why
During summer daytime, the lower frequency bands like 160 metres and 80 metres struggle to bounce off the ionosphere because the sun strongly absorbs these signals in the lower D layer. 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