After an automatic direction finding antenna has been installed, which part needs calibration?

After an automatic direction finding antenna has been installed, which part needs calibration?

• A. The transmitter power supply
• B. The sensing loop antenna
• C. The receiver's display
• D. The grounding strap

Answer: (B)

The directing accuracy of an automatic direction finding system hinges on calibrating the sensing loop antenna. This loop is the directional element that forms the radiation pattern used to determine where the beacon lies. After installation, small shifts in physical alignment or changes in electrical characteristics can skew bearings, so calibrating the loop aligns its reference with the aircraft’s bearing scale and ensures the displayed direction is accurate. The other parts aren’t responsible for setting the bearing: the transmitter power supply isn’t part of direction finding, the grounding strap is for static protection, and while the receiver’s display shows the bearing, it relies on the loop’s calibration to be correct.

The directing accuracy of an automatic direction finding system hinges on calibrating the sensing loop antenna. This loop is the directional element that forms the radiation pattern used to determine where the beacon lies. After installation, small shifts in physical alignment or changes in electrical characteristics can skew bearings, so calibrating the loop aligns its reference with the aircraft’s bearing scale and ensures the displayed direction is accurate. The other parts aren’t responsible for setting the bearing: the transmitter power supply isn’t part of direction finding, the grounding strap is for static protection, and while the receiver’s display shows the bearing, it relies on the loop’s calibration to be correct.