Which of the following bands may provide long-distance communications via the ionosphere’s F region during the peak of the sunspot cycle?
The correct answer is A: 6 and 10 meters. During the peak of the sunspot cycle, the 6-meter and 10-meter bands may provide long-distance communications via the ionosphere's F region. The F region becomes intensely ionized during high sunspot activity, allowing it to refract these higher frequencies.
During sunspot maximum, the ionosphere is so intensely ionized that it can refract frequencies as high as 6 meters (50-54 MHz) and 10 meters (28-29.7 MHz). This is when these bands really 'open up' for long-distance DX work. At other times in the sunspot cycle, these bands may not support F region propagation, or it may be less reliable. The 6-meter and 10-meter bands are particularly sensitive to sunspot activity.
Exam Tip
F region sunspot max = 6 and 10 meters. Remember: During sunspot maximum, the 6-meter and 10-meter bands can provide long-distance F region propagation. These are the highest frequency bands that can use F region.
Memory Aid
"**F** region **S**unspot **M**ax = **6** and **1**0 meters (think 'FSM = 6 and 10')"
Real-World Application
During a sunspot maximum, you're operating on 6 meters and making contacts over 2000 miles via F region propagation - something that's impossible during low sunspot periods. The intensely ionized F region during sunspot maximum can refract 6-meter signals, allowing these long-distance contacts. Similarly, 10 meters provides excellent F region DX during sunspot peaks.
FCC Part 97.3Key Concepts
Why Other Options Are Wrong
Option B: Incorrect. 23 centimeters (around 1.2 GHz) is too high for F region propagation, even during sunspot maximum. The ionosphere doesn't effectively refract such high frequencies.
Option C: Incorrect. 70 centimeters and 1.25 meters are generally too high for F region propagation, even during high sunspot activity.
Option D: Incorrect. Not all options are correct. Only 6 and 10 meters can provide F region propagation during sunspot maximum.
题目解析
The correct answer is A: 6 and 10 meters. During the peak of the sunspot cycle, the 6-meter and 10-meter bands may provide long-distance communications via the ionosphere's F region. The F region becomes intensely ionized during high sunspot activity, allowing it to refract these higher frequencies. During sunspot maximum, the ionosphere is so intensely ionized that it can refract frequencies as high as 6 meters (50-54 MHz) and 10 meters (28-29.7 MHz). This is when these bands really 'open up' for long-distance DX work. At other times in the sunspot cycle, these bands may not support F region propagation, or it may be less reliable. The 6-meter and 10-meter bands are particularly sensitive to sunspot activity.
考试技巧
F region sunspot max = 6 and 10 meters. Remember: During sunspot maximum, the 6-meter and 10-meter bands can provide long-distance F region propagation. These are the highest frequency bands that can use F region.
记忆口诀
**F** region **S**unspot **M**ax = **6** and **1**0 meters (think 'FSM = 6 and 10')
实际应用示例
During a sunspot maximum, you're operating on 6 meters and making contacts over 2000 miles via F region propagation - something that's impossible during low sunspot periods. The intensely ionized F region during sunspot maximum can refract 6-meter signals, allowing these long-distance contacts. Similarly, 10 meters provides excellent F region DX during sunspot peaks.
错误选项分析
Option B: Incorrect. 23 centimeters (around 1.2 GHz) is too high for F region propagation, even during sunspot maximum. The ionosphere doesn't effectively refract such high frequencies. Option C: Incorrect. 70 centimeters and 1.25 meters are generally too high for F region propagation, even during high sunspot activity. Option D: Incorrect. Not all options are correct. Only 6 and 10 meters can provide F region propagation during sunspot maximum.
知识点
F region, Sunspot cycle, 6-meter band, 10-meter band
Verified Content
Question from official FCC Technician Class question pool. Explanation reviewed by licensed amateur radio operators.