Question
How is the far-field elevation pattern of a vertically polarized antenna affected by being mounted over seawater versus soil?
Answer Options
- A) Radiation at low angles decreases
- B) Additional lobes appear at higher elevation angles
- C) Separate elevation lobes will combine into a single lobe
- D) Radiation at low angles increases
Correct Answer: D
Explanation
The performance of a vertical antenna relies heavily on the conductivity of the ground beneath it, as the ground acts as the necessary second element of the antenna system. Seawater is an extremely good conductor (high conductivity), while most soil is a relatively poor conductor (high loss).
When a vertically polarized antenna is mounted over seawater versus soil, the lower loss and higher conductivity of the seawater significantly reduce ground losses, making the ground reflection more efficient. This results in radiation at low angles increases. This increase in low-angle radiation is highly desirable for long-distance DX skip propagation.
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