Perhaps the most common type of transmission line is the coax. The coax is a very nice way to create a
transmission line. Understanding coax can be helpful when working with it. The nice part about coax is that
it can be bent and flexible unlike most pcb transmission lines.
Coax Inductance Description
The basic coax cable is constructed with an inner trace and a shield separated by dielectric. The property
of coax that is nice is the transverse electric magnetic (TEM) mode, which means that the magnetic and
electric fields are perpendicular to the direction of the wave propagation. The characteristic impedance is
primarily determined by the distance from the conductor to the shield as well as the dielectric constant of
material separating them.
Coax Cable Transmission Line Models
Models have been created to approximate the characteristics of the coax cable transmission line.
The characteristic impedance of a coax is:
