Tool Introduction

Perhaps the most common type of transmission line is coaxial cable. Coaxial cable is a great way to create a transmission line. When working with coaxial cable, it is helpful to understand coaxial cable. The advantage of coaxial cable is that it can bend and is flexible, unlike most pcb transmission lines.

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.