What are the two antennas required for the operation of an ADF?

The correct answer involves understanding the configuration of an Automatic Direction Finder (ADF) system. An ADF uses two types of antennas: the loop antenna and the sense antenna.

The loop antenna is primarily responsible for receiving the radio signals from the ground-based Non-Directional Beacons (NDBs). It is designed to pick up signals with a directional sensitivity, allowing the ADF system to determine the direction of the incoming signal based on how the signal is oriented relative to the aircraft. This capability provides the necessary information to guide the aircraft toward the beacon.

The sense antenna complements the loop by helping to distinguish between signal direction and potential noise. It assists in providing a reference to determine the phase of the signal so that the ADF can accurately interpret the bearing of the signal.

Thus, the combination of the loop and sense antennas is critical for the accurate operation of the ADF, allowing it to reliably determine bearings and assist in navigation.