Question
Which region of the atmosphere can refract or bend HF and VHF radio waves?
Answer Options
- A) The stratosphere
- B) The troposphere
- C) The ionosphere
- D) The mesosphere
Correct Answer: C
Explanation
The ionosphere is the layer of the Earth’s atmosphere located roughly 60 km to 400 km above the surface, where solar radiation causes gas molecules to become ionized (electrically charged). This layer is responsible for refracting (bending) HF radio waves, allowing them to bounce back toward Earth and travel long distances around the globe.
This phenomenon, called skywave propagation, is the primary method for long-distance communication on all HF amateur bands. The troposphere (the lowest layer, where weather occurs) can also bend signals, but this effect is generally limited to VHF and UHF signals over relatively shorter distances (T3C06).
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