Deep Dive: G4D05
The correct answer is D: It is 100 times more powerful. How a signal that reads 20 dB over S9 compares to one that reads S9 on a properly calibrated S meter is that it is 100 times more powerful. Each 10 dB represents a 10:1 power ratio, so 20 dB represents 100:1 (10 × 10). For amateur radio operators, this helps understand S meter readings. Understanding this helps when comparing signals.
Why Other Answers Are Wrong
Option A: Incorrect. 10 times less powerful is wrong - 20 dB over S9 is more powerful, not less. The signal is stronger, not weaker. Option B: Incorrect. 20 times less powerful is wrong - 20 dB over S9 is more powerful. The signal is stronger, not weaker. Option C: Incorrect. 20 times more powerful is wrong - 20 dB represents 100:1 power ratio, not 20:1. Each 10 dB is 10:1, so 20 dB is 100:1.
Exam Tip
20 dB over S9 vs S9 = 100 times more powerful. Think '2'0 dB = '2' × '1'0 dB = '1'00:1 power ratio. Each 10 dB represents 10:1 power ratio, so 20 dB represents 100:1. Not 10 or 20 times - 100 times.
Memory Aid
20 dB over S9 vs S9 = 100 times more powerful. Think '2'0 dB = '2' × '1'0 dB = '1'00:1. Each 10 dB represents 10:1 power ratio, so 20 dB represents 100:1. Significant power difference.
Real-World Example
Signal A reads S9, Signal B reads S9+20 dB. Signal B is 100 times more powerful than Signal A. Each 10 dB represents a 10:1 power ratio (10 dB = 10×, 20 dB = 100×). This is a huge difference in signal strength.
Source & Coverage
Question Pool: 2023-2027 Question Pool
Subelement: G4D
Reference: 2023-2027 Question Pool · G4 - Amateur Radio Practices
Key Concepts
Verified Content
Question from the official FCC General Class pool. Explanation reviewed by licensed amateur radio operators and mapped to the G4D topic.