Which of the following is used to determine if an antenna is resonant at the desired operating frequency?

The use of an antenna analyzer is crucial for determining if an antenna is resonant at the desired operating frequency. An antenna analyzer measures the standing wave ratio (SWR) and other parameters, such as impedance and reactance, which are essential in evaluating how well the antenna is matched to the transmission line at a specific frequency.

By providing a direct reading of SWR, the analyzer enables the operator to see if the antenna is resonant; a low SWR indicates good resonance and a proper match, while a high SWR suggests that the antenna is not resonant at that frequency, leading to potential signal loss or damage to the transmitter. Thus, the antenna analyzer is designed specifically for this purpose, making it the appropriate choice for assessing antenna performance in relation to its operating frequency.

Other instruments, while useful in their own right, do not serve this specific function. A VTVM (Vacuum Tube Volt Meter) is primarily for measuring voltage and does not provide the necessary information regarding antenna resonance. A Q meter measures the quality factor of circuits but is not specifically designed for analyzing antennas. A frequency counter is used to measure the frequency of signals rather than assessing an antenna's resonance. Therefore, the effectiveness of the antenna analyzer in this context