Question
What is generally the best time for long-distance 10 meter band propagation via the F region?
Answer Options
- A) From dawn to shortly after sunset during periods of high sunspot activity
- B) From shortly after sunset to dawn during periods of high sunspot activity
- C) From dawn to shortly after sunset during periods of low sunspot activity
- D) From shortly after sunset to dawn during periods of low sunspot activity
Correct Answer: A
Explanation
The F region of the ionosphere is the primary layer for long-distance HF communication. Its ability to refract signals is directly related to solar activity, making it strongest during periods of high sunspot activity. The F region is also primarily dependent on the sun’s direct ionization.
Therefore, the best time for long-distance propagation on the 10-meter band is from dawn to shortly after sunset during periods of high sunspot activity. During low sunspot activity or at night, the 10-meter band usually appears ‘dead’ because the sun’s radiation is no longer strong enough to sustain the F region ionization for high frequencies.
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