Wikipedia:Today's featured article/March 15, 2019

Planar transmission lines are flat, ribbon-shaped transmission lines with conductors, or in some cases dielectric (insulating) strips. They are used to interconnect components on printed circuits and integrated circuits working at microwave frequencies, since the planar lines are suited to the manufacturing methods for these components. Transmission line theory is used when the line is longer than a large fraction of a wavelength. At microwave frequencies, this distance is measured in millimetres, which is small enough that these lines can be used for constructing components as well as interconnecting them. The cross-section of the line is usually kept constant so that its electrical behaviour is highly predictable. The first planar transmission line, stripline, was conceived during World War II by Robert M. Barrett; other types in modern use include microstrip, suspended stripline, and coplanar waveguide.