What effect does a sudden ionospheric disturbance have on the daytime ionospheric propagation?
The correct answer is B: It disrupts signals on lower frequencies more than those on higher frequencies. The effect of a sudden ionospheric disturbance (SID) on daytime ionospheric propagation is that it disrupts signals on lower frequencies more than those on higher frequencies. SIDs are caused by solar flares that increase D-layer absorption, which affects lower frequencies more. For amateur radio operators, this means lower bands (160m, 80m, 40m) are more affected than higher bands. Understanding this helps explain SID effects.
Exam Tip
SID effect = disrupts lower frequencies more than higher. Think 'S'ID = 'S'olar 'I'onospheric 'D'isturbance disrupts 'L'ower frequencies 'M'ore. D-layer absorption from solar flares affects lower frequencies more severely. Not enhancement, not satellites, not just night side.
Memory Aid
"SID effect = disrupts lower frequencies more than higher. Think 'S'ID = 'S'olar 'I'onospheric 'D'isturbance disrupts 'L'ower frequencies. D-layer absorption from solar flares affects lower frequencies more. Key SID characteristic."
Real-World Application
A solar flare causes a sudden ionospheric disturbance. The D-layer absorption increases, disrupting propagation. Lower bands (80m, 40m) are severely affected, while higher bands (20m, 15m) may still work. The increased absorption affects lower frequencies more because they're more dependent on ionospheric propagation.
Key Concepts
Why Other Options Are Wrong
Option A: Incorrect. SIDs don't enhance propagation - they disrupt it. SIDs cause increased absorption, not enhancement.
Option C: Incorrect. SIDs don't disrupt satellite communications more - they affect ionospheric propagation, not satellite paths. Satellite communications use different paths.
Option D: Incorrect. SIDs affect daytime propagation, not just night side - they're caused by solar flares that affect the sunlit side of Earth.
题目解析
The correct answer is B: It disrupts signals on lower frequencies more than those on higher frequencies. The effect of a sudden ionospheric disturbance (SID) on daytime ionospheric propagation is that it disrupts signals on lower frequencies more than those on higher frequencies. SIDs are caused by solar flares that increase D-layer absorption, which affects lower frequencies more. For amateur radio operators, this means lower bands (160m, 80m, 40m) are more affected than higher bands. Understanding this helps explain SID effects.
考试技巧
SID effect = disrupts lower frequencies more than higher. Think 'S'ID = 'S'olar 'I'onospheric 'D'isturbance disrupts 'L'ower frequencies 'M'ore. D-layer absorption from solar flares affects lower frequencies more severely. Not enhancement, not satellites, not just night side.
记忆口诀
SID effect = disrupts lower frequencies more than higher. Think 'S'ID = 'S'olar 'I'onospheric 'D'isturbance disrupts 'L'ower frequencies. D-layer absorption from solar flares affects lower frequencies more. Key SID characteristic.
实际应用示例
A solar flare causes a sudden ionospheric disturbance. The D-layer absorption increases, disrupting propagation. Lower bands (80m, 40m) are severely affected, while higher bands (20m, 15m) may still work. The increased absorption affects lower frequencies more because they're more dependent on ionospheric propagation.
错误选项分析
Option A: Incorrect. SIDs don't enhance propagation - they disrupt it. SIDs cause increased absorption, not enhancement. Option C: Incorrect. SIDs don't disrupt satellite communications more - they affect ionospheric propagation, not satellite paths. Satellite communications use different paths. Option D: Incorrect. SIDs affect daytime propagation, not just night side - they're caused by solar flares that affect the sunlit side of Earth.
知识点
Sudden ionospheric disturbance, SID, Lower frequencies, D-layer absorption
Verified Content
Question from official FCC General Class question pool. Explanation reviewed by licensed amateur radio operators.