Ham Radio General Class Practice Test

What can significantly affect the readings of an antenna analyzer?

1. Changing the feedline length

2. The presence of nearby antennas

3. Frequency shift during operation

4. Grounding issues

The correct answer is: The presence of nearby antennas

The presence of nearby antennas can significantly affect the readings of an antenna analyzer due to interaction and coupling between the antennas. When two antennas are in close proximity, they can influence each other's performance through mutual coupling, which can distort the impedance and the SWR (Standing Wave Ratio) readings displayed on the analyzer. This interaction can result in misleading data concerning an antenna's characteristics, such as resonance and bandwidth, making it appear as though the analyzer is measuring the performance of multiple antennas rather than the one being tested. In contrast, while changing the feedline length can impact impedance, it's often accounted for during antenna tuning, and the effect may be predictable. Frequency shifts during operation can alter the operating point of an antenna, but these changes are generally understood and manageable in a controlled testing environment. Grounding issues, while potentially affecting the overall system performance and safety, are less likely to be the immediate cause of erratic readings from an analyzer compared to the direct impact of nearby antennas.