Principles of Communication: Propagation MCQ

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PropagationMediumQuestion 20224

Question

Sky-wave propagation relies on:

A
Reflection from the ground
B
Refraction/reflection by the ionosphere
Correct
C
Total internal reflection in optical fibre
D
Diffraction around mountains

Correct answer

Refraction/reflection by the ionosphere

Explanation

The ionosphere (layers D, E, F₁, F₂ at 60–400 km altitude) contains free electrons that refract HF waves (3–30 MHz) back to Earth, enabling long-distance short-wave radio communication.

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