Ham Amateur Radio Technician Practice Exam

What type of waves can auroras reflect to enhance communication?

1. Ultra-high frequency signals

2. Very low frequency signals

3. VHF signals

4. Longwave signals

The correct answer is: VHF signals

Auroras have the ability to reflect certain types of radio waves due to the ionization of the atmosphere caused by solar activity. VHF signals, which are part of the Very High Frequency band, typically range from 30 MHz to 300 MHz. These frequencies can be scattered and reflected by the irregularities in the ionosphere created by auroras. The reflection happens because the energetic particles striking the atmosphere during auroral activity can enhance the ionization, allowing these frequencies to bounce off the aurora and travel beyond the normal range of line-of-sight communication. This phenomenon can thus extend the reach of communications for amateur radio operators. While other frequency ranges, such as ultra-high frequency and very low frequency signals, are influenced by the ionosphere as well, the VHF range is particularly suitable for reflection under these specific conditions. Longwave signals tend to travel differently and are less effective for communication over distances when using auroras as reflective mediums.