What is standing wave ratio (SWR)?
The correct answer is A: A measure of how well a load is matched to a transmission line. Standing Wave Ratio (SWR) is a measure of how well a load is matched to a transmission line. SWR indicates the ratio of maximum to minimum voltage (or current) on a transmission line, which reflects how well the antenna impedance matches the feed line impedance. A 1:1 SWR means perfect match, higher SWR means mismatch. For amateur radio operators, SWR is the primary indicator of antenna system performance and impedance matching. Understanding SWR helps diagnose antenna and feed line problems.
Exam Tip
SWR = measure of load matching to transmission line. Think 'S'WR = 'S'tanding 'W'ave 'R'atio = 'S'hows 'W'ell 'R'adiator matches. Measures how well antenna impedance matches feed line. Not about amplifier efficiency, transmitter efficiency, or ground quality.
Memory Aid
"SWR = measure of load matching. Think 'S'WR = 'S'tanding 'W'ave 'R'atio = 'S'hows 'W'ell 'R'adiator matches. Measures impedance matching between antenna and feed line. Lower is better (1:1 is perfect)."
Real-World Application
You measure SWR on your antenna system. A 1:1 reading means your antenna presents exactly 50 ohms to the feed line - perfect match. A 3:1 reading means significant mismatch - the antenna impedance doesn't match the 50-ohm feed line well. SWR tells you how well matched your system is.
Key Concepts
Why Other Options Are Wrong
Option B: Incorrect. SWR isn't the ratio of amplifier power output to input - that's amplifier efficiency. SWR measures impedance matching, not power ratios.
Option C: Incorrect. SWR isn't transmitter efficiency ratio - efficiency is output power divided by input power. SWR is about impedance matching.
Option D: Incorrect. SWR isn't an indication of ground connection quality - ground affects other things, but SWR measures impedance matching between feed line and antenna.
题目解析
The correct answer is A: A measure of how well a load is matched to a transmission line. Standing Wave Ratio (SWR) is a measure of how well a load is matched to a transmission line. SWR indicates the ratio of maximum to minimum voltage (or current) on a transmission line, which reflects how well the antenna impedance matches the feed line impedance. A 1:1 SWR means perfect match, higher SWR means mismatch. For amateur radio operators, SWR is the primary indicator of antenna system performance and impedance matching. Understanding SWR helps diagnose antenna and feed line problems.
考试技巧
SWR = measure of load matching to transmission line. Think 'S'WR = 'S'tanding 'W'ave 'R'atio = 'S'hows 'W'ell 'R'adiator matches. Measures how well antenna impedance matches feed line. Not about amplifier efficiency, transmitter efficiency, or ground quality.
记忆口诀
SWR = measure of load matching. Think 'S'WR = 'S'tanding 'W'ave 'R'atio = 'S'hows 'W'ell 'R'adiator matches. Measures impedance matching between antenna and feed line. Lower is better (1:1 is perfect).
实际应用示例
You measure SWR on your antenna system. A 1:1 reading means your antenna presents exactly 50 ohms to the feed line - perfect match. A 3:1 reading means significant mismatch - the antenna impedance doesn't match the 50-ohm feed line well. SWR tells you how well matched your system is.
错误选项分析
Option B: Incorrect. SWR isn't the ratio of amplifier power output to input - that's amplifier efficiency. SWR measures impedance matching, not power ratios. Option C: Incorrect. SWR isn't transmitter efficiency ratio - efficiency is output power divided by input power. SWR is about impedance matching. Option D: Incorrect. SWR isn't an indication of ground connection quality - ground affects other things, but SWR measures impedance matching between feed line and antenna.
知识点
SWR, Standing Wave Ratio, Impedance matching, Antenna matching
Verified Content
Question from official FCC Technician Class question pool. Explanation reviewed by licensed amateur radio operators.