Basic Qualification · B-007 Radio wave propagation · B-007-006-010
La fréquence optimale de travail est la plus efficace pour les grandes distances sur HF. Par rapport à la fréquence maximale utilisable, elle est généralement:
- Alégèrement plus basse
- Ble double de la fréquence maximale utilisable (FMU)
- Cla moitié de la fréquence maximale utilisable (FMU)
- Dlégèrement plus haute
Correct answer: A — légèrement plus basse. Question tirée de la banque officielle d'ISDE.
Why
The optimum working frequency is set slightly lower than the maximum usable frequency to ensure the signal reliably reaches the intended distance even if atmospheric conditions change. 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