phantom facility

A transmission facility derived with repeating coils from two or more pairs of wires. [T1.238-1994/97] Synonyms phantom circuit, phantom pair. Note: The name "phantom" is derived from the fact that balanced, center-tapped transformers, called "repeat(ing)" coils in telephone parlance, can be used, e.g., in conjunction with two twisted pairs, to create a third, electrically isolated transmission path ("phantom pair") by splitting the latter's electrical signal between the two twisted pairs (called "side circuits") in such a fashion as to cancel inductive interference from the phantom circuit to the side circuits, and vice versa.