The outer insulating layer in a coaxial cable, often referred to as the jacket, is an additional layer of insulation that surrounds the outer conductor (shield) and the dielectric layer. This jacket serves multiple purposes:
- Mechanical Protection: The outer jacket provides protection to the cable from physical stress, bending, abrasion, and environmental factors like moisture, chemicals, and UV radiation. It helps prevent damage to the internal components of the cable.
- Electrical Isolation: The jacket ensures that there is no electrical contact between the cable and its surroundings, reducing the risk of electrical interference and potential short circuits.
- Color Coding and Identification: Jackets can be manufactured in different colors to help identify different types of cables, applications, or functions. This is especially useful in complex network installations where multiple cables are used.
- Flame Resistance: In certain applications, the jacket may be designed to provide fire resistance and retardant properties to ensure safety in case of fire.
- Environmental Resistance: The outer insulating layer can offer protection against harsh environmental conditions, such as extreme temperatures or exposure to chemicals.
- Aesthetics: The outer jacket can also provide a neat and professional appearance to the cables, especially in visible or indoor installations.
Overall, the outer insulating layer plays a vital role in maintaining the cable’s structural integrity, electrical performance, and protection against external factors. The material used for the jacket depends on the specific requirements of the cable’s application and the surrounding environment. Common materials for the jacket include PVC (polyvinyl chloride), PE (polyethylene), LSZH (low smoke zero halogen), and more.