Transmission Lines and Parameters

Abstract Transmission lines are defined as waveguiding structures that can support transverse electromagnetic (TEM) waves or quasi‐TEM waves. This article concentrates on five commonly used transmission‐line structures. The transmission‐line parameters are first introduced in the derivation of the telegrapher's equations by dividing the transmission line into electrically small segments that can be described by the lumped‐element circuit theory. The transmission‐line parameters are then derived from rigorous electromagnetic field analysis. Five commonly used transmission lines—parallel‐plate waveguides, coaxial cables, two‐wire lines, striplines, and microstrip lines—are presented, and the techniques used to extract their corresponding transmission‐line parameters are given. A common integrated circuit (IC)‐level transmission‐line structure is presented, and the challenges in parameter extraction for future micro‐ and nanoscale transmission lines are also discussed.