May 6, 2014

FCC Technician Exam Question Of The Day (T7C06)

Q) What does an SWR reading of 4:1 mean?

A) An impedance mismatch

NJ2X Notes:
Amateur radios require an impedance match of 50-ohms in the coaxial cable, antenna, or any other device connected.  A mismatch between the radio and any of the devices in the chain will cause a greater than 1:1 (perfect match) SWR.

SWR is an abbreviation of standing-wave ratio.   SWR on a transmission line in an antenna system represents the ratio of forward to reflected voltage on the line.  A perfect 1:1 ration occurs when all parts of the antenna system are matched correctly to one another.

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