What is the effect of fog and rain on signals in the 10 meter and 6 meter bands?
The correct answer is B: There is little effect. Fog and rain have little effect on signals in the 10-meter and 6-meter bands because these frequencies are not significantly absorbed by water in the atmosphere. The absorption effects become significant at much higher frequencies (microwave range).
While precipitation can significantly affect microwave frequencies (10 GHz and above), HF and lower VHF frequencies (like 10 meters at 28-29 MHz and 6 meters at 50-54 MHz) pass through fog and rain with minimal absorption. The water droplets are too small relative to the wavelength to cause significant absorption or scattering. This is why 10-meter and 6-meter communications can continue effectively even in bad weather.
Exam Tip
Fog/rain on 10m/6m = Little effect. Remember: Fog and rain have little effect on 10-meter and 6-meter signals. Significant absorption only occurs at much higher (microwave) frequencies.
Memory Aid
"**F**og/**R**ain **1**0m/**6**m = **F**ine (think 'FR10/6 = F' = Fine, little effect)"
Real-World Application
You're operating on 6 meters during a rainstorm. Your signal strength and communication range remain essentially the same as in clear weather. The rain doesn't significantly affect your 6-meter signals because the wavelength is too long for the water droplets to cause significant absorption. This is different from microwave frequencies where rain can severely reduce range.
FCC Part 97.3Key Concepts
Why Other Options Are Wrong
Option A: Incorrect. Absorption is significant at microwave frequencies, not at 10-meter and 6-meter frequencies. These lower frequencies aren't significantly absorbed by precipitation.
Option C: Incorrect. Deflection (scattering) is also minimal at these frequencies. Water droplets don't significantly deflect 10-meter and 6-meter signals.
Option D: Incorrect. Precipitation doesn't increase range. It might slightly affect propagation, but not in a way that increases range.
题目解析
The correct answer is B: There is little effect. Fog and rain have little effect on signals in the 10-meter and 6-meter bands because these frequencies are not significantly absorbed by water in the atmosphere. The absorption effects become significant at much higher frequencies (microwave range). While precipitation can significantly affect microwave frequencies (10 GHz and above), HF and lower VHF frequencies (like 10 meters at 28-29 MHz and 6 meters at 50-54 MHz) pass through fog and rain with minimal absorption. The water droplets are too small relative to the wavelength to cause significant absorption or scattering. This is why 10-meter and 6-meter communications can continue effectively even in bad weather.
考试技巧
Fog/rain on 10m/6m = Little effect. Remember: Fog and rain have little effect on 10-meter and 6-meter signals. Significant absorption only occurs at much higher (microwave) frequencies.
记忆口诀
**F**og/**R**ain **1**0m/**6**m = **F**ine (think 'FR10/6 = F' = Fine, little effect)
实际应用示例
You're operating on 6 meters during a rainstorm. Your signal strength and communication range remain essentially the same as in clear weather. The rain doesn't significantly affect your 6-meter signals because the wavelength is too long for the water droplets to cause significant absorption. This is different from microwave frequencies where rain can severely reduce range.
错误选项分析
Option A: Incorrect. Absorption is significant at microwave frequencies, not at 10-meter and 6-meter frequencies. These lower frequencies aren't significantly absorbed by precipitation. Option C: Incorrect. Deflection (scattering) is also minimal at these frequencies. Water droplets don't significantly deflect 10-meter and 6-meter signals. Option D: Incorrect. Precipitation doesn't increase range. It might slightly affect propagation, but not in a way that increases range.
知识点
Precipitation, 10-meter band, 6-meter band, Signal absorption
Verified Content
Question from official FCC Technician Class question pool. Explanation reviewed by licensed amateur radio operators.