FAA AMT (Aviation Maintenance Technician) Airframe Practice Exam

ADF stands for Automatic Direction Finding, and is a navigational system that uses radio signals to determine the direction of a fixed or mobile source. GPS antennas (A), VOR antennas (B), and transponder antennas (D) are all used for other types of navigation systems and are not included in the ADF system. Sense and loop antennas (C) are specifically used for ADF systems to receive and process signals, making it the correct answer.