T3C10: F region: Of the following bands may provide

Q: 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. 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.

Updated: Dec 9, 2025 | Source: 2022-2026 Question Pool | Topic: T3C

T3C10T3C

Which of the following bands may provide long-distance communications via the ionosphere’s F region during the peak of the sunspot cycle?

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Deep Dive: T3C10

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.

Why Other Answers 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.

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 Example

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.

Source & Coverage

Question Pool: 2022-2026 Question Pool

Subelement: T3C

Reference: FCC Part 97.3

Key Concepts

F region Sunspot cycle 6-meter band 10-meter band

Verified Content

Question from the official FCC Technician Class pool. Explanation reviewed by licensed amateur radio operators and mapped to the T3C topic.