What is the most common dielectric material in hardline coaxial cable?

Foamed polyethylene is the most common dielectric material used in hardline coaxial cable due to its excellent balance of performance characteristics. This material offers low dielectric loss, which is crucial for maintaining signal integrity over long distances. Additionally, foamed polyethylene provides good insulation properties and a lightweight profile, making it suitable for various applications in telecommunications and broadcasting.

The structure of foamed polyethylene, with its air-filled cells, contributes to its effective dielectric properties by reducing the material's density without compromising its strength. This results in a cable that exhibits less signal attenuation and better overall performance, which is vital for modern communication systems.

In contrast, while glass fiber is often associated with optical fibers, it is not used in hardline coaxial cables. Polyvinyl chloride (PVC) is more commonly utilized as a jacket or outer protective layer in cables, rather than as a dielectric material. Lastly, air-filled materials do have applications in certain types of coaxial cables, but they are less commonly used in hardline coaxial constructions compared to foamed polyethylene. Thus, foamed polyethylene stands out as the preferred dielectric due to its superior combination of properties for the intended application.