Basic Qualification · B-007 Radio wave propagation · B-007-001-004
On VHF and higher frequencies, why does the radio horizon extend beyond the visible horizon?
- A Normal refraction in the troposphere
- B Ionization in the troposphere
- C Diffraction caused by soil conductivity
- D Refraction in the D-region
Correct answer: A — Normal refraction in the troposphere. From the official ISED question bank, verified word for word.
Why
The atmosphere in the lowest layer, called the troposphere, acts like a lens that slowly bends radio waves downward as they travel. 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.