Why is skip propagation via the F2 region longer than that via the other ionospheric regions?
The correct answer is C: Because it is the highest. Why skip propagation via the F2 region is longer than that via the other ionospheric regions is because it is the highest. F2 is the highest ionospheric region (250-400 km), so signals travel farther before returning to Earth, creating longer skip distances. For amateur radio operators, this explains why F2 provides the longest single-hop distances. Understanding this helps explain F2 propagation characteristics.
Exam Tip
F2 longest skip = because it is highest. Think 'F'2 = 'F'urthest (highest) = 'F'urthest skip. F2 is highest ionospheric region (250-400 km), so signals travel farther before returning to Earth. Not densest, not Doppler, not temperature inversions - just highest.
Memory Aid
"F2 longest skip = because it is highest. Think 'F'2 = 'F'urthest (highest). F2 is highest ionospheric region (250-400 km), so signals travel farther before returning to Earth. Height determines skip distance."
Real-World Application
F2 region is at 300 km altitude, while E region is at 120 km. A signal refracted by F2 travels much farther before returning to Earth because it's higher - the signal path is longer. This is why F2 provides single-hop distances of about 2,500 miles, while E region provides about 1,200 miles.
Key Concepts
Why Other Options Are Wrong
Option A: Incorrect. F2 isn't the densest - density varies, but height is the key factor for skip distance, not density.
Option B: Incorrect. Doppler effect isn't the reason - Doppler affects frequency, not skip distance. Height is the key factor.
Option D: Incorrect. Temperature inversions aren't the reason - those affect tropospheric propagation, not ionospheric skip. Height is the key factor.
题目解析
The correct answer is C: Because it is the highest. Why skip propagation via the F2 region is longer than that via the other ionospheric regions is because it is the highest. F2 is the highest ionospheric region (250-400 km), so signals travel farther before returning to Earth, creating longer skip distances. For amateur radio operators, this explains why F2 provides the longest single-hop distances. Understanding this helps explain F2 propagation characteristics.
考试技巧
F2 longest skip = because it is highest. Think 'F'2 = 'F'urthest (highest) = 'F'urthest skip. F2 is highest ionospheric region (250-400 km), so signals travel farther before returning to Earth. Not densest, not Doppler, not temperature inversions - just highest.
记忆口诀
F2 longest skip = because it is highest. Think 'F'2 = 'F'urthest (highest). F2 is highest ionospheric region (250-400 km), so signals travel farther before returning to Earth. Height determines skip distance.
实际应用示例
F2 region is at 300 km altitude, while E region is at 120 km. A signal refracted by F2 travels much farther before returning to Earth because it's higher - the signal path is longer. This is why F2 provides single-hop distances of about 2,500 miles, while E region provides about 1,200 miles.
错误选项分析
Option A: Incorrect. F2 isn't the densest - density varies, but height is the key factor for skip distance, not density. Option B: Incorrect. Doppler effect isn't the reason - Doppler affects frequency, not skip distance. Height is the key factor. Option D: Incorrect. Temperature inversions aren't the reason - those affect tropospheric propagation, not ionospheric skip. Height is the key factor.
知识点
F2 region, Longest skip, Highest region, Single-hop distance
Verified Content
Question from official FCC General Class question pool. Explanation reviewed by licensed amateur radio operators.