What reading on an SWR meter indicates a perfect impedance match between the antenna and the feed line?
The correct answer is C: 1:1. A reading of 1:1 on an SWR meter indicates a perfect impedance match between the antenna and feed line. SWR (Standing Wave Ratio) is the ratio of maximum to minimum voltage (or current) on a transmission line. When SWR is 1:1, there's no standing wave, meaning all power is transferred from the feed line to the antenna with no reflection. For amateur radio operators, 1:1 SWR is the ideal condition, indicating perfect impedance matching. While 1.5:1 or 2:1 is often acceptable, 1:1 is perfect. Understanding SWR readings is essential for antenna tuning and system optimization.
Exam Tip
Perfect match = 1:1 SWR. Think '1:1 = 'P'erfect match. The ratio 1:1 means no standing wave - all power transfers. Lower numbers are better, and 1:1 is the best possible.
Memory Aid
"Perfect match = 1:1 SWR. Think '1:1 = 'O'ne to 'O'ne = 'O'ptimal match. No standing wave, all power transfers. The lower the better, and 1:1 is perfect."
Real-World Application
You're tuning your antenna and watching the SWR meter. As you adjust the antenna length, the SWR decreases from 3:1 to 2:1 to 1.5:1, and finally reaches 1:1. At 1:1, the meter shows perfect match - all your transmitter power is being transferred to the antenna with no reflection. This is the ideal condition for maximum power transfer and minimum feed line losses.
Key Concepts
Why Other Options Are Wrong
Option A (50:50): Incorrect. This isn't a valid SWR reading format. SWR is expressed as a ratio like 1:1, 2:1, etc., not as 50:50.
Option B (Zero): Incorrect. SWR cannot be zero - the minimum possible SWR is 1:1, which represents a perfect match. Zero would mean no signal, which isn't possible.
Option D (Full Scale): Incorrect. Full scale on an SWR meter indicates maximum SWR (poor match), not a perfect match. Full scale means high SWR and significant mismatch.
题目解析
The correct answer is C: 1:1. A reading of 1:1 on an SWR meter indicates a perfect impedance match between the antenna and feed line. SWR (Standing Wave Ratio) is the ratio of maximum to minimum voltage (or current) on a transmission line. When SWR is 1:1, there's no standing wave, meaning all power is transferred from the feed line to the antenna with no reflection. For amateur radio operators, 1:1 SWR is the ideal condition, indicating perfect impedance matching. While 1.5:1 or 2:1 is often acceptable, 1:1 is perfect. Understanding SWR readings is essential for antenna tuning and system optimization.
考试技巧
Perfect match = 1:1 SWR. Think '1:1 = 'P'erfect match. The ratio 1:1 means no standing wave - all power transfers. Lower numbers are better, and 1:1 is the best possible.
记忆口诀
Perfect match = 1:1 SWR. Think '1:1 = 'O'ne to 'O'ne = 'O'ptimal match. No standing wave, all power transfers. The lower the better, and 1:1 is perfect.
实际应用示例
You're tuning your antenna and watching the SWR meter. As you adjust the antenna length, the SWR decreases from 3:1 to 2:1 to 1.5:1, and finally reaches 1:1. At 1:1, the meter shows perfect match - all your transmitter power is being transferred to the antenna with no reflection. This is the ideal condition for maximum power transfer and minimum feed line losses.
错误选项分析
Option A (50:50): Incorrect. This isn't a valid SWR reading format. SWR is expressed as a ratio like 1:1, 2:1, etc., not as 50:50. Option B (Zero): Incorrect. SWR cannot be zero - the minimum possible SWR is 1:1, which represents a perfect match. Zero would mean no signal, which isn't possible. Option D (Full Scale): Incorrect. Full scale on an SWR meter indicates maximum SWR (poor match), not a perfect match. Full scale means high SWR and significant mismatch.
知识点
SWR, Standing Wave Ratio, Impedance matching, Perfect match
Verified Content
Question from official FCC Technician Class question pool. Explanation reviewed by licensed amateur radio operators.