What is a Coaxial Cable? 

Coaxial cables are a type of cable that is used by cable TV and that is common for data communications. 

Taking a a round cross-section of the cable, one would find a single center solid wire symmetrically surrounded by a braided or foil conductor. Between the center wire and foil is a insulating dialectric. This dialectric has a large affect on the fundamental characteristics of the cable. In this lab, we show the how the permittivity and permeability of the dialectric contributes to the cable's inductance and capacitance. Also, these values affect how quickly electrical data is travels through the wire.

Data is transmitted through the center wire, while the outer braided layer serves as a line to ground. Both of these conductors are parallel and share the same axis. This is why the wire is called coaxial!

Just like all electrical components, coaxial cables have a characteristic impedance. This impedance depends on the dialectric material and the radii of each conducting material  As shown in this lab, the impedance affects how the cable interacts with other electrical components. 

In this lab we used a RG-580/U coaxial cable. This is just one of many types of cables that are used today to transmit data. The dialectric of the RG-580/U was made of polyethylene. The radius of our cable's inner copper wire was .42mm and there was 2.208mm of polyethylene between the inner wire and outer mesh conductors.

References:

Dictionary of PC Hardware and Data Communications Terms 

If you don't see what's so remarkable about coaxial cables, maybe you should think about it some more!

Introduction | Cable Info | Lab Procedure and Results | Conclusions