In which frequency range does ADF operate?

The correct choice indicates that ADF, or Automatic Direction Finder, operates primarily in the LF (Low Frequency) and MF (Medium Frequency) bands. This is significant because these frequency ranges enable ADF equipment to receive low-frequency radio signals, which are typically transmitted by non-directional beacons and various navigation aids. The LF/MF bands allow for extended range and reliable performance, especially during long-distance navigation over oceans or remote areas where other navigation systems may not be available.

In contrast, other frequency bands have different characteristics. The HF (High Frequency) band is generally utilized for long-range communication rather than the specific directional navigation that ADF provides. VHF (Very High Frequency) and UHF (Ultra High Frequency) ranges are more commonly used for line-of-sight communications and radar systems, which do not align with the primary function of an ADF. Thus, understanding that ADF operates in the LF/MF range is crucial for recognizing its role in aviation navigation systems.