How many antennas does an ADF require?

An Automatic Direction Finder (ADF) typically requires one antenna to function as it is designed to receive radio signals broadcast from non-directional beacons (NDBs). However, the system may employ additional antennas for improved performance, such as enhancing signal reception or reducing interference. While the primary antenna serves its essential function, additional antennas can provide redundancy or assist in orientation.

In the context of your answer, two antennas are often employed to achieve the necessary direction-finding capability, where one acts as a receiving antenna and the other enhances signal clarity. This setup allows the ADF to interpret the signals more accurately and maintain aircraft orientation concerning the ground station.

Therefore, the presence of two antennas is common in practice to optimize the direction-finding capabilities of an ADF system, affirming the choice that specifies two antennas for optimal performance in various aviation scenarios.