Which device is used to measure radio-frequency power during tests?

A wattmeter is the correct device used to measure radio-frequency power during tests. It is specifically designed to quantify the amount of electrical power, in watts, that is being transmitted or used by a radio-frequency signal. This measurement is crucial in evaluating the performance of various RF equipment, ensuring that systems operate within their specified power levels for optimal performance and safety.

In contrast, a voltmeter is utilized mainly to measure voltage and would not provide the specific information about power that a wattmeter does. A multimeter can measure voltage, current, and resistance, but it lacks the specialized capability to measure power directly in RF systems. An oscilloscope is primarily used for visualizing waveforms rather than quantifying power directly, making it unsuitable for this specific measurement. Thus, the wattmeter stands out as the most appropriate tool for accurately assessing RF power during testing.