Editing Antenna analyzer (section)

===High and low power methods===
Many transmitters include an [[SWR meter]] in the output circuits which works by measuring the [[Reflection (electrical)|reflected wave]] from the antenna back to the [[transmitter]], which is minimal when the antenna is matched. Reflected power from a badly tuned antenna can present an improper load at the transmitter which can damage it. The [[SWR meter]] requires about 5–10&nbsp;watts of outgoing signal from the radio to register the reflected power (if any), and then only indicates the relative degree of mismatch, not the reactive and resistive impedance seen at the end of the antenna's feedline.

A complex-impedance antenna analyzer typically only requires a few milliwatts of power be applied to the antenna, and typically provides its own signal, not requiring any test signal from a transmitter. Using a low-power test signal avoids damaging the analyzer when testing a badly-matched antenna.<ref name=Carr-2000>{{cite book |first=Joseph J. |last=Carr |date=1 October 1999 |chapter=Chapter&nbsp;5 Spectrum and network analyzers; Chapter&nbsp;12 Antenna and transmission line measurements |title=Practical Radio Frequency Test and Measurement: A technician's handbook |edition=1st |pages=102, 319 |publisher=Newnes |isbn=0-7506-7161-0 |postscript=,}} {{ISBN|978-0-7506-7161-3}}</ref> In addition, because its signal power is very low, the analyzer can be used for frequencies outside of the transmit bands licensed to its operator, and thus measure antenna performance over an unrestricted range of frequencies.