Question T9B12
From subelement T9 - T9B
What is standing wave ratio (SWR)?
Why is this correct?
SWR measures impedance matching between your transmission line and load (antenna). Perfect matching yields 1:1 SWR, meaning all power transfers efficiently. Option B describes amplifier gain, not SWR. Option C refers to overall transmitter efficiency, which involves multiple factors beyond impedance matching. Option D relates to RF grounding, not the specific impedance relationship that SWR measures.
Memory tip
Remember the definition pattern: SWR always involves two components being matched—transmission line and load. Any SWR question asking 'what is' will focus on this impedance matching relationship. If you see power ratios or efficiency mentioned, those describe different measurements entirely.
Learn more
In practical operation, SWR readings guide antenna system troubleshooting. A 1:1 reading indicates perfect impedance matching, while higher ratios like 3:1 suggest problems requiring investigation. Modern transceivers monitor SWR continuously, automatically reducing output power when impedance mismatches threaten solid-state amplifier transistors. Understanding SWR helps you optimize your station's radiated power and prevent equipment damage during transmission.
Think about it
Why do you think impedance matching matters more at higher frequencies compared to audio frequencies in your home stereo system?