Apparatus for electrical line communication that includes a coupler at each of two or more locations along a pair of lines, the coupler having capacitive circuits serially connected with an air-core transformer. The capacitive circuit is designed to resonate with the air-core transformer at a preselected...http://www.google.fr/patents/US5559377?utm_source=gb-gplus-shareBrevet US5559377 - Transformer coupler for communication over various lines
Transformer coupler for communication over various lines
