What standing wave ratio results from connecting a 50-ohm feed line to a 200-ohm resistive load?
The correct answer is A: 4:1. The standing wave ratio that results from connecting a 50-ohm feed line to a 200-ohm resistive load is 4:1. SWR = Zload/Zline (or Zline/Zload, whichever is greater) = 200/50 = 4:1. For amateur radio operators, this is a basic SWR calculation. Understanding this helps when calculating SWR.
Exam Tip
50Ω feed line to 200Ω load = 4:1 SWR. Think 'S'WR = 'S'imple ratio = '2'00/'5'0 = '4':1. SWR = Zload/Zline (or larger ratio) = 200/50 = 4:1. Not 1:4, not 2:1, not 1:2 - just 4:1.
Memory Aid
"50Ω feed line to 200Ω load = 4:1 SWR. Think 'S'WR = '2'00/'5'0 = '4':1. SWR = Zload/Zline (or larger ratio). Basic SWR calculation."
Real-World Application
A 50-ohm feed line connected to a 200-ohm resistive load. SWR = 200/50 = 4:1. The standing wave ratio is the ratio of the load impedance to the feed line impedance (or the larger ratio). This is a basic SWR calculation - impedance mismatch creates SWR.
Key Concepts
Why Other Options Are Wrong
Option B (1:4): Incorrect. 1:4 is the inverse - SWR is always ≥ 1:1, so it's 4:1, not 1:4. SWR is the larger ratio.
Option C (2:1): Incorrect. 2:1 is too low - 200/50 = 4:1, not 2:1. Calculation error.
Option D (1:2): Incorrect. 1:2 is the inverse and too low - SWR is 4:1, not 1:2. SWR is always ≥ 1:1.
题目解析
The correct answer is A: 4:1. The standing wave ratio that results from connecting a 50-ohm feed line to a 200-ohm resistive load is 4:1. SWR = Zload/Zline (or Zline/Zload, whichever is greater) = 200/50 = 4:1. For amateur radio operators, this is a basic SWR calculation. Understanding this helps when calculating SWR.
考试技巧
50Ω feed line to 200Ω load = 4:1 SWR. Think 'S'WR = 'S'imple ratio = '2'00/'5'0 = '4':1. SWR = Zload/Zline (or larger ratio) = 200/50 = 4:1. Not 1:4, not 2:1, not 1:2 - just 4:1.
记忆口诀
50Ω feed line to 200Ω load = 4:1 SWR. Think 'S'WR = '2'00/'5'0 = '4':1. SWR = Zload/Zline (or larger ratio). Basic SWR calculation.
实际应用示例
A 50-ohm feed line connected to a 200-ohm resistive load. SWR = 200/50 = 4:1. The standing wave ratio is the ratio of the load impedance to the feed line impedance (or the larger ratio). This is a basic SWR calculation - impedance mismatch creates SWR.
错误选项分析
Option B (1:4): Incorrect. 1:4 is the inverse - SWR is always ≥ 1:1, so it's 4:1, not 1:4. SWR is the larger ratio. Option C (2:1): Incorrect. 2:1 is too low - 200/50 = 4:1, not 2:1. Calculation error. Option D (1:2): Incorrect. 1:2 is the inverse and too low - SWR is 4:1, not 1:2. SWR is always ≥ 1:1.
知识点
Standing wave ratio, 50-ohm feed line, 200-ohm load, SWR calculation
Verified Content
Question from official FCC General Class question pool. Explanation reviewed by licensed amateur radio operators.