A test instrument used to determine the frequency and relative power of RF signals is called a(n) _____.

The field strength analyzer is specifically designed to measure the strength of radio frequency (RF) signals and can provide valuable information about their relative power and frequency. This tool is particularly useful in wireless communication because it helps engineers and technicians ensure that signals are transmitted effectively and within regulatory limits.

Unlike an oscilloscope, which primarily displays waveforms and does not focus on frequency or power readings, the field strength analyzer directly measures the electromagnetic field strength of RF signals, allowing for precise analysis and optimization of wireless communication systems. Similarly, while a power meter measures the power of the RF signals, it does not typically provide information about the frequency. A signal generator, on the other hand, is used to produce signals of various frequencies and amplitudes but does not measure existing signals.

Thus, the field strength analyzer is the most relevant instrument for determining both the frequency and relative power of RF signals, making it the correct answer.