Question
What are “extraordinary” and “ordinary” waves?
Answer Options
- A) Extraordinary waves exhibit rare long-skip propagation, compared to ordinary waves, which travel shorter distances
- B) Independently propagating, elliptically polarized waves created in the ionosphere
- C) Long-path and short-path waves
- D) Refracted rays and reflected waves
Correct Answer: B
Explanation
When a linearly polarized radio wave enters the ionosphere, the plasma and the Earth’s magnetic field cause the wave to split into two separate components due to a phenomenon called birefringence. These two components travel along slightly different paths and at different speeds through the plasma before emerging back into free space or ground level.
These two components are called the ordinary wave and the extraordinary wave. They are independently propagating, elliptically polarized waves created in the ionosphere. The differences in their path and polarization are a key cause of phase shifting and signal fading, particularly on the HF bands.
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