Coax Cables: Insulation and Shielding

Coax Cables: Insulation and Shielding

Look at the walls of your home, and pretend you have X-ray vision. Behind the drywall you see some form of insulation. This keeps the rooms in your home comfortable during extreme heat and cold.

Behind the insulation you’ll find the home’s exterior surface. This is a shield of aluminum, wood, stone, or brick. It protects the insulation and drywall from getting wet, drying out, or being pulled away by heavy winds. Without this shield, the insulation evaporates, and your home is at risk.

Same Goes for the Coax Cable

This is how your coax cable is designed. A center conductor connects the signal from your antenna setup to your CB transceiver. The conductor is insulated from potential dangers. And that insulation is protected by a shield. You don’t see any of this because it’s all covered by an outer layer called a jacket.

What Are They Made Of?

Since you don’t see the insulation or shielding on a normal basis, here’s a breakdown of their compositions.

The insulation is normally made from either foam (aka, poly-foam) or a plastic (aka poly-vinyl or polypropylene). Out of the two, plastic is tougher. While poly-foam provides a faster transfer of the signal, it degrades quicker. And though there is minimal loss of signal velocity and frequency in poly-vinyl, it is barely noticeable from an operational point of view.

The shielding prevents internal leakage and external interference. The most common form of this protection is bare or tinned copper wire. The tighter this wire is braided around the insulation the stronger the protection. Today, many coaxials contain 90% shielding. Choosing anything less than that increases the risk of power bleed and interference.

Do you still have questions? Contact our CB Radio Supply specialists to get a better understanding. They’ll review your requirements to find the best-insulated and shielded coax cable available.