Which frequency will have the least attenuation for long-distance skip propagation?
The correct answer is A: Just below the MUF. The frequency that will have the least attenuation for long-distance skip propagation is just below the MUF (Maximum Usable Frequency). Frequencies just below MUF have the best signal-to-noise ratio and least attenuation. For amateur radio operators, operating just below MUF provides optimal propagation. Understanding this helps when selecting operating frequencies.
Exam Tip
Least attenuation = just below MUF. Think 'L'east 'A'ttenuation = 'L'ower than 'M'UF. Frequencies just below MUF have the best signal-to-noise ratio and least attenuation. Not above LUF, not critical frequency - just below MUF.
Memory Aid
"Least attenuation = just below MUF. Think 'L'east 'A'ttenuation = 'L'ower than 'M'UF. Frequencies just below MUF have best signal-to-noise ratio and least attenuation. Optimal frequency for long-distance skip propagation."
Real-World Application
MUF for your path is 21 MHz. You operate at 20.5 MHz (just below MUF) for least attenuation and best signal quality. Operating at 19 MHz (above LUF but well below MUF) would work but have more attenuation. Operating at 22 MHz (above MUF) wouldn't work at all. Just below MUF is optimal.
Key Concepts
Why Other Options Are Wrong
Option B: Incorrect. Just above LUF (Lowest Usable Frequency) isn't optimal - frequencies just below MUF have less attenuation. LUF is the minimum, not the optimum.
Option C: Incorrect. Just below critical frequency isn't the answer - MUF is the key, not critical frequency. Critical frequency is different from MUF.
Option D: Incorrect. Just above critical frequency may exceed MUF - you want just below MUF for least attenuation.
题目解析
The correct answer is A: Just below the MUF. The frequency that will have the least attenuation for long-distance skip propagation is just below the MUF (Maximum Usable Frequency). Frequencies just below MUF have the best signal-to-noise ratio and least attenuation. For amateur radio operators, operating just below MUF provides optimal propagation. Understanding this helps when selecting operating frequencies.
考试技巧
Least attenuation = just below MUF. Think 'L'east 'A'ttenuation = 'L'ower than 'M'UF. Frequencies just below MUF have the best signal-to-noise ratio and least attenuation. Not above LUF, not critical frequency - just below MUF.
记忆口诀
Least attenuation = just below MUF. Think 'L'east 'A'ttenuation = 'L'ower than 'M'UF. Frequencies just below MUF have best signal-to-noise ratio and least attenuation. Optimal frequency for long-distance skip propagation.
实际应用示例
MUF for your path is 21 MHz. You operate at 20.5 MHz (just below MUF) for least attenuation and best signal quality. Operating at 19 MHz (above LUF but well below MUF) would work but have more attenuation. Operating at 22 MHz (above MUF) wouldn't work at all. Just below MUF is optimal.
错误选项分析
Option B: Incorrect. Just above LUF (Lowest Usable Frequency) isn't optimal - frequencies just below MUF have less attenuation. LUF is the minimum, not the optimum. Option C: Incorrect. Just below critical frequency isn't the answer - MUF is the key, not critical frequency. Critical frequency is different from MUF. Option D: Incorrect. Just above critical frequency may exceed MUF - you want just below MUF for least attenuation.
知识点
MUF, Least attenuation, Skip propagation, Frequency selection
Verified Content
Question from official FCC General Class question pool. Explanation reviewed by licensed amateur radio operators.