Q) Which of the following instruments can be used to determine if an antenna is resonant at the desired operating frequency?
A) An antenna analyzer
An antenna analyzer is an extremely useful device for amateur radio. We use the MFJ-269 - HF/VHF/UHF SWR ANALYZER, COUNTER. We have used it to identifying problems with our coaxial cables as well as designing and building antennas. There are all kinds of interesting things you can do with it beyond these basic uses.