PURPOSE: To attain ≥10km of transmission range for an information transmission line along a transmission/distribution line and a power/sub station by utilizing an overhead earth line of the transmission line and arranging periodically straight line conductor rods between the opposed two earth lines.

CONSTITUTION: The straight line conductors are arranged periodically along the transmission line perpendicularly to the overhead earth lines 1 in parallel two line constitution, in the transmission lines using ≥2 overhead earth lines placed at a comparatively high place. As the method of arrangement of the straight line conductor rods 2, there are 3 kinds as one end short-circuit of straight line conductor rods and both end open. The conductor rods are coupled electromagnetically with input/output elements and other conductor rods, and the electromagnetic energy coupled to each conductor rod is coupled repetitively to the next conductor rods via mutual impedance to send the electromagnetic energy.