Goubau line

Description

The Goubau line itself consists of a single wire conductor coated with dielectric material.{{cite book

A G-line is a type of waveguide, rather than a wire in an electric circuit. The G-line functions by slowing the propagation velocity of EM waves below the free-space velocity, causing the wavefronts to slightly bend inwards towards the conductor, which keeps the waves entrained. Bends of large radius are tolerated, but too sharp a bend in the single wire will cause the line to radiate and lose energy into space. In theory the dielectric coating is a requirement, it slows the wave and focuses it along the wire. 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.

Other structures besides horns have been used to couple radio waves into and out of Goubau lines; waves can be "launched" from planar structures like tapered coplanar waveguides at much higher frequencies, into the terahertz band. The dimension of the single metallic conductor is then typically 1 μm. T. Akalin, “High Resolution Biosensor based on Surface Wave Transmission Lines at THz Frequencies”, 35th European Microwave Conf., 3-7 Oct. 2005, Paris, France and

T. Akalin, "Single-wire transmission lines at terahertz frequencies", IEEE Transactions on Microwave Theory and Techniques (IEEE-MTT), Volume 54, Issue 6, June 2006 Page(s): 2762 - 2767

The Goubau line conducts energy via one-dimensional electromagnetic surface waves, analogous to the two-dimensional surface waves called ground waves that carry the signal from MF AM broadcasting stations to home AM radios. 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.

Patents

• , "Surface wave transmission line". George J. E. Goubau
• , "Launching and receiving of surface waves". George J. E. Goubau.

References