Which of the following can be determined with a directional wattmeter?

A directional wattmeter is an instrument designed to measure both forward power traveling from the transmitter to the antenna and reflected power bouncing back from the antenna to the transmitter. Standing Wave Ratio (SWR) is a mathematical relationship between this forward and reflected power. Because a directional wattmeter provides both of these crucial measurements, you can easily use its readings to calculate the SWR on your feedline. The other options are incorrect because they relate to the physical radiation characteristics of the antenna or the atmosphere. A directional wattmeter only measures the RF power inside the transmission line, so it cannot determine antenna front-to-back ratio or radio wave propagation.