An ensemble including a pipe for transporting substances which can flow, the pipe having a structure forming a coaxial transmission line including: a first tubular layer of electrically conductive material; a second tubular layer of electrically conductive material; and at least one first layer of dielectric material mounted in-between the first and the second layers of electrically conductive material, such that: the first layer of electrically conductive material forms an outer conductor of a section of the coaxial transmission line; the second layer of electrically conductive material forms an inner conductor of the section of the coaxial transmission line, and further including an electromagnetic coupler coupling the coaxial transmission line with a complementary coaxial transmission line carried by a pipe complementary to the pipe.