What does air coupling refer to in the inductive locating method?

• A. The union of the signal from the transmitter to the receiver in the absence of a conductor.
• B. A method to improve signal strength on a powered line.
• C. A condition where the antenna is misaligned.
• D. The process of grounding the transmitter.

Answer: (A)

Air coupling is the direct transfer of the transmitted signal through the air from the transmitter to the receiver when there is no buried conductor present. In inductive locating, the transmitter creates an alternating magnetic field, and this field can be picked up by the receiver even if there isn’t a conductor linking them. It’s a real but usually weaker form of coupling compared to the signal induced onto a target conductor, and it explains why you can detect a signal even with no buried line in the path.