Deep Dive: G9A05
The correct answer is B: Attenuation increases. How the attenuation of coaxial cable changes with increasing frequency is that attenuation increases. Coaxial cable loss increases with frequency due to skin effect and dielectric losses. For amateur radio operators, this is why higher frequencies have more feed line loss. Understanding this helps when selecting feed lines for different bands.
Why Other Answers Are Wrong
Option A: Incorrect. Attenuation isn't independent of frequency - it increases with frequency. Frequency independence is wrong. Option C: Incorrect. Attenuation doesn't decrease with frequency - it increases. Decrease is wrong. Option D: Incorrect. Marconi's Law of Attenuation isn't a real thing - attenuation increases with frequency due to skin effect and dielectric losses. Marconi's Law doesn't exist.
Exam Tip
Coax attenuation vs frequency = increases with frequency. Think 'C'oax 'A'ttenuation = 'C'ontinues 'A'scending with frequency. Coaxial cable loss increases with frequency due to skin effect and dielectric losses. Not independent, not decreases, not Marconi's Law - just increases.
Memory Aid
Coax attenuation vs frequency = increases with frequency. Think 'C'oax 'A'ttenuation = 'C'ontinues 'A'scending. Coaxial cable loss increases with frequency due to skin effect and dielectric losses. Important for feed line selection.
Real-World Example
Coaxial cable: At 1 MHz, loss might be 0.5 dB per 100 feet. At 100 MHz, loss might be 2 dB per 100 feet. At 1 GHz, loss might be 5 dB per 100 feet. Attenuation increases with frequency due to skin effect (current flows on conductor surface) and dielectric losses. This is why higher frequencies have more feed line loss.
Source & Coverage
Question Pool: 2023-2027 Question Pool
Subelement: G9A
Reference: 2023-2027 Question Pool · G9 - Antennas and Feed Lines
Key Concepts
Verified Content
Question from the official FCC General Class pool. Explanation reviewed by licensed amateur radio operators and mapped to the G9A topic.