Question
What is the effect of vegetation on UHF and microwave signals?
Answer Options
- A) Knife-edge diffraction
- B) Absorption
- C) Amplification
- D) Polarization rotation
Correct Answer: B
Explanation
On UHF (Ultra High Frequency) and microwave bands (frequencies above 300 MHz), signals are highly susceptible to interactions with physical objects. Vegetation, especially foliage (leaves and branches), contains a high water content. As radio signals pass through the foliage, the water molecules in the leaves effectively absorb the RF energy, converting it into heat.
This signal loss is called absorption, and it significantly attenuates (weakens) the signal. This is why it is difficult to maintain reliable communications with handheld radios in heavily wooded areas or dense urban environments with many trees blocking the line of sight.
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