Basic Qualification · B-007 Radio wave propagation · B-007-006-003
What does maximum usable frequency mean?
- A The lowest frequency that is most absorbed by the ionosphere
- B The highest frequency at which a signal will reach a given destination
- C The lowest frequency at which a signal will reach a given destination
- D The highest frequency that is most absorbed by the ionosphere
Correct answer: B — The highest frequency at which a signal will reach a given destination. From the official ISED question bank, verified word for word.
Why
Maximum usable frequency marks the upper limit where a radio signal can still bounce off the ionosphere to reach a specific location; if you go higher, the wave passes straight through into space instead of returning to Earth. The full explanation — and one for every question — is in Pro.
Practise this section
How signals travel: the ionosphere and its layers, skip, ground wave, sporadic E, and which bands work when.