CATV and CCTV Coax structured cabling

Closed Circuit and Cable Television systems are a normal part of any new commercial construction.  Inspired Excellence has been installing coaxial video cables since 1999, and we're pretty good at it (see pictures in our gallery).  

Coaxial cables carry a nominal impedance between 35 and 185 ohms.  The three most common are 50 ohms, 75 ohms (most likely used at home for your TV), and 93 ohms (rarely used).  

Coax cable will support much higher bandwidths than unshielded twisted pair (UTP) cable.  Over coaxial cable, the most efficient transfer of energy occurs when all parts of the system have the same impedance.


The most common type of coax (Flexible Coax) uses a braided shield of fine wires.  This braid helps the coax bend more easily, but there's a price:  RF (radio frequency) signals leak through the small gaps in the braid.  To counteract this attenuation (energy loss), manufacturers add several layers of braid and place thin foil between the layers.  This provides a much better shielding coverage for greater effectiveness (less attenuation).  
IE normally uses a quad shield (two layers of foil, two of braid) for 75-ohm applications.

Even though coax is normally a small piece of the puzzle, it still remains critical within our customers' infrastructure.  Coax has been the medium of choice for high fidelity audio, television, satellite and broadband communications.