ABSTRACT
A class of transmission lines referred to as planar transmission lines is used over a very wide frequency range starting from centimetric to the submillimetric zone to guide the electromagnetic waves. These have the same characterising parameters (viz. Z0, γ, α, β, c, υp and υg) as applicable to other transmission structures. Their geometry allows the control of these parameters, particularly the characteristic impedance by defining dimensions in a single plane. This feature allows a complete transmission line circuit to be fabricated in one step by using thin film and photolithography techniques similar to those used for making printed circuits for low-frequency electronic circuitry.
