Which instrument can be used to determine SWR?

SWR (Standing Wave Ratio) is a measure of how well an antenna is impedance-matched to its transmission line. It is determined by comparing the forward power (energy traveling from the transmitter to the antenna) against the reflected power (energy bouncing back from the antenna due to a mismatch). A directional wattmeter is an instrument specifically designed to measure RF power flowing in both directions. By taking the forward and reflected power readings, you can easily calculate the SWR. Standard electrical meters like voltmeters or ohmmeters cannot measure moving RF power, and "iambic pentameter" is a humorous distractor related to poetry.