A two-wire line is a Line of transmission, used in high frequencies, and consisted of two parallel wire separated by an insulator.

It is mainly characterized by:

• its characteristic Impedance Zc, typically standardized with 300 ohms for the antennas;
• its Constant of weakening α at a given frequency, which translates the losses in the line.

Traditionally, the two-wire line is used to connect a reception antenna TV to a television set. It is economic, but suffers from several disadvantages compared to its competitor, the coaxial Ligne:

• it must be placed sufficiently far from the walls, gutters etc because the presence of objects influences the propagation of the signal in the line;
• the losses increase with the wire of time, of the particles of dust settling on the insulating support;
high frequency
• , when the distance B between the drivers is not negligible any more compared to the wavelength of the signal being propagated in the line, the line radiates, which causes losses being added to the other losses due to the resistance of wire and the losses in the dielectric one.