Goubau line

[2][3][4] The dielectric coated transmission line was invented by F. Harms[5] in 1907 and George J. E. Goubau[6] in 1950, based on work on surface waves on wires from 1899 by Arnold Sommerfeld.

[7][8] It is used as a feedline at UHF to link high frequency transmitters and receivers to their antennas,[2][3] and in scientific research.

Parallel line (twin lead) and coaxial cable, which are used to carry lower frequency radio signals, have high losses at the upper end of the UHF band, and are almost useless for distances over 100 feet (33 meters).

But some users note that in practice the finite conductivity of metals may produce a similar effect, and a bare G-line can entrain a propagating wave.

The ability of surface waves to bend and follow the contour of a conductor explains why AM radio stations can be received on the far side of hills, and how over-the-horizon radar works.