Definition
An electronic component in an Automatic Direction Finder (ADF) system that compares the signal strengths received from the loop antenna's two perpendicular coils and resolves them into a single bearing to the tuned radio station. It effectively rotates the loop antenna's directional sensitivity electronically rather than mechanically.
Plain English
A device inside the ADF that figures out which direction a radio signal is coming from by comparing how strongly two fixed antennas pick it up, then points the needle accordingly.
Context Anchor
Seen in aircraft maintenance manuals, inspection procedures, and adjustment tasks where a part’s angle or range of movement must be measured.
Derivation
From the Greek 'gonia' meaning 'angle' and '-meter' meaning 'measure.' Literally an angle-measurer. In the ADF, the angle being measured is the bearing from the aircraft to the radio station.
Why Pilots Care
The goniometer is what allows the ADF bearing pointer to move smoothly and accurately without any moving antenna parts on the airframe. Maintenance technicians need to recognize it as the signal-processing heart of the ADF when troubleshooting bearing errors or pointer faults.
Analogy
Think of a goniometer as a protractor made for real aircraft parts instead of lines on paper.
Example Sentence 1
When the ADF bearing needle wandered erratically, the technician suspected a fault in the goniometer rather than the loop antenna itself.
Example Sentence 2
After replacing the goniometer, the mechanic verified that the ADF could still resolve station bearings correctly.