Deep Dive: G3A04
The correct answer is D: 15 meters, 12 meters, and 10 meters. The least reliable bands for long-distance communications during periods of low solar activity are 15 meters, 12 meters, and 10 meters. These higher frequency bands require more ionization to propagate, which is lacking during low solar activity. For amateur radio operators, these bands may be dead during solar minimum. Understanding this helps explain why higher bands need more solar activity.
Why Other Answers Are Wrong
Option A (80m, 160m): Incorrect. Lower bands are more reliable during low solar activity - they need less ionization. 80m and 160m often work better during solar minimum. Option B (60m, 40m): Incorrect. These bands are more reliable during low solar activity - they need less ionization than higher bands. Option C (30m, 20m): Incorrect. 30m and 20m are more reliable than 15m, 12m, 10m during low solar activity - they're lower frequency and need less ionization.
Exam Tip
Least reliable during low solar activity = 15m, 12m, 10m. Think 'L'ow 'S'olar = 'L'ess reliable on 'S'uper high frequencies (15m, 12m, 10m). Higher frequency bands need more ionization, so they're least reliable during low solar activity. Lower bands are more reliable.
Memory Aid
Least reliable during low solar activity = 15m, 12m, 10m. Think 'L'ow 'S'olar = 'L'ess reliable on 'S'uper high frequencies. Higher frequency bands (15m, 12m, 10m) need more ionization, so they're least reliable during low solar activity.
Real-World Example
During solar minimum (low sunspot numbers), 15 meters, 12 meters, and 10 meters may be completely dead - no propagation. These higher bands need strong ionization that's lacking during low solar activity. Meanwhile, lower bands (40m, 80m) may still work because they need less ionization.
Source & Coverage
Question Pool: 2023-2027 Question Pool
Subelement: G3A
Reference: 2023-2027 Question Pool · G3 - Radio Wave Propagation
Key Concepts
Verified Content
Question from the official FCC General Class pool. Explanation reviewed by licensed amateur radio operators and mapped to the G3A topic.