We considered the propagation of a short pulse in the picosecond range in coupled lines with a ratio of phase velocities of anti-phase and in-phase waves of 3:1. We showed experimentally a special aspect in the interference of in-phase and anti-phase waves in such structures, which leads to the input pulse separation between three ports without a significant energy loss associated with the reflection from the input. The wave interference was found to lead to a change in the directional properties of the structures under consideration and a separation of the pulse spectral components between the ports.