Deep Dive: G4B10
The correct answer is A: Standing wave ratio. What can be determined with a directional wattmeter is standing wave ratio (SWR). Directional wattmeters measure forward and reflected power, allowing SWR calculation. For amateur radio operators, this is a primary use of directional wattmeters. Understanding this helps when measuring SWR.
Why Other Answers Are Wrong
Option B: Incorrect. Directional wattmeters don't determine antenna front-to-back ratio - that requires measuring signal strength from different directions. Front-to-back ratio needs field strength measurements. Option C: Incorrect. Directional wattmeters don't determine RF interference - that requires spectrum analyzers or other equipment. Interference measurement is different. Option D: Incorrect. Directional wattmeters don't determine radio wave propagation - that requires propagation monitoring. Propagation is about conditions, not power measurements.
Exam Tip
Directional wattmeter determines = standing wave ratio (SWR). Think 'D'irectional 'W'attmeter = 'D'etermines 'W'ave ratio (SWR). Measures forward and reflected power, allowing SWR calculation. Not front-to-back ratio, not interference, not propagation - just SWR.
Memory Aid
Directional wattmeter determines = standing wave ratio (SWR). Think 'D'irectional 'W'attmeter = 'D'etermines 'W'ave ratio. Measures forward and reflected power, allowing SWR calculation. Primary use of directional wattmeters.
Real-World Example
You use a directional wattmeter to measure SWR. The wattmeter measures forward power (e.g., 100 watts) and reflected power (e.g., 10 watts). From these measurements, you can calculate SWR. Directional wattmeters are the standard tool for measuring SWR.
Source & Coverage
Question Pool: 2023-2027 Question Pool
Subelement: G4B
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 G4B topic.