What is the purpose of a corona ball on an HF mobile antenna?
The correct answer is D: To reduce RF voltage discharge from the tip of the antenna while transmitting. The purpose of a corona ball on an HF mobile antenna is to reduce RF voltage discharge from the tip of the antenna while transmitting. Corona balls are smooth, rounded objects that reduce sharp points where high RF voltage can cause corona discharge. For amateur radio operators, this prevents RF losses and interference. Understanding this helps when using mobile antennas.
Exam Tip
Corona ball purpose = reduce RF voltage discharge from antenna tip. Think 'C'orona 'B'all = 'C'ontrols 'B'right discharge (corona). Smooth, rounded object reduces sharp points where high RF voltage causes corona discharge. Not bandwidth, not Q, not physical protection - just corona reduction.
Memory Aid
"Corona ball purpose = reduce RF voltage discharge from antenna tip. Think 'C'orona 'B'all = 'C'ontrols 'B'right discharge. Smooth, rounded object reduces sharp points where high RF voltage causes corona discharge. Prevents RF losses and interference."
Real-World Application
You operate an HF mobile antenna with high RF voltage at the tip. Without a corona ball, sharp points can cause corona discharge (visible glow, RF losses, interference). You add a corona ball (smooth, rounded object) at the tip. This reduces sharp points, preventing corona discharge and improving efficiency.
Key Concepts
Why Other Options Are Wrong
Option A: Incorrect. Corona balls don't narrow operating bandwidth - they don't affect bandwidth. Bandwidth narrowing isn't the purpose.
Option B: Incorrect. Corona balls don't increase antenna Q - they don't affect Q significantly. Q increase isn't the purpose.
Option C: Incorrect. Corona balls don't reduce damage from striking objects - that's about antenna strength, not corona balls. Physical protection isn't the purpose.
题目解析
The correct answer is D: To reduce RF voltage discharge from the tip of the antenna while transmitting. The purpose of a corona ball on an HF mobile antenna is to reduce RF voltage discharge from the tip of the antenna while transmitting. Corona balls are smooth, rounded objects that reduce sharp points where high RF voltage can cause corona discharge. For amateur radio operators, this prevents RF losses and interference. Understanding this helps when using mobile antennas.
考试技巧
Corona ball purpose = reduce RF voltage discharge from antenna tip. Think 'C'orona 'B'all = 'C'ontrols 'B'right discharge (corona). Smooth, rounded object reduces sharp points where high RF voltage causes corona discharge. Not bandwidth, not Q, not physical protection - just corona reduction.
记忆口诀
Corona ball purpose = reduce RF voltage discharge from antenna tip. Think 'C'orona 'B'all = 'C'ontrols 'B'right discharge. Smooth, rounded object reduces sharp points where high RF voltage causes corona discharge. Prevents RF losses and interference.
实际应用示例
You operate an HF mobile antenna with high RF voltage at the tip. Without a corona ball, sharp points can cause corona discharge (visible glow, RF losses, interference). You add a corona ball (smooth, rounded object) at the tip. This reduces sharp points, preventing corona discharge and improving efficiency.
错误选项分析
Option A: Incorrect. Corona balls don't narrow operating bandwidth - they don't affect bandwidth. Bandwidth narrowing isn't the purpose. Option B: Incorrect. Corona balls don't increase antenna Q - they don't affect Q significantly. Q increase isn't the purpose. Option C: Incorrect. Corona balls don't reduce damage from striking objects - that's about antenna strength, not corona balls. Physical protection isn't the purpose.
知识点
Corona ball, HF mobile antenna, RF voltage discharge, Corona prevention
Verified Content
Question from official FCC General Class question pool. Explanation reviewed by licensed amateur radio operators.