Question
What is the purpose of a corona ball on an HF mobile antenna?
Answer Options
- A) To narrow the operating bandwidth of the antenna
- B) To increase the “Q” of the antenna
- C) To reduce the chance of damage if the antenna should strike an object
- D) To reduce RF voltage discharge from the tip of the antenna while transmitting
Correct Answer: D
Explanation
When a high amount of radio frequency (RF) power is applied to the end of a whip antenna, the sharp tip can create an extremely high voltage gradient, especially on electrically short antennas where the voltage is very high. This can cause the air to ionize, leading to a visible blue-white corona discharge and a loss of RF energy.
A corona ball (a rounded metallic object) is placed on the tip of the antenna to reduce RF voltage discharge from the tip of the antenna while transmitting. The rounded surface distributes the high RF voltage over a larger area, reducing the voltage gradient and preventing the corona discharge from occurring, thereby conserving power.
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