RF coaxial dielectric insulation cable wires than just play the role of final transmission performance is mainly determined only after the insulation, and therefore the choice of dielectric material and its structure is very important. All important properties, such as attenuation, impedance and return loss, both with large insulated relationship. Insulation of the most important requirements are:
Low relative dielectric constant and dielectric loss angle is small factor, in order to ensure attenuation;
Consistent with the structure, in order to ensure uniform impedance, return loss;
Mechanical properties and stability in order to guarantee a long life;
Waterproof.
Physical high foam insulation can achieve all of the above requirements. With advanced extrusion and injection gas technology and special materials, foaming degree can reach more than 80%, so the performance of the air insulated electrical cables closer. Gas injection method, nitrogen gas is injected directly into the dielectric material within the extruder, the process is also known as physical foaming methods. As opposed to this method of chemical foaming, the foaming degree can only reach about 50%, the dielectric loss is large. Gas Injection foamed structure consistent method by means uniform impedance, return loss.
Our RF cable insulating material due to dielectric loss angle is small, the foaming degree and has very good electrical properties. Foam dielectric properties is more important at high frequencies, it is this special foam structure determines the very low attenuation performance in high frequency cable.
Unique multi-layer insulation (thin layer - foamed layer - outside TLC) coextrusion process can be uniformly closed foamed structure, with stable mechanical properties, high strength and good moisture performance characteristics. For the cable in a wet environment remains very good electrical properties, we specifically designed a cable: the outer surface of foam insulation layer plus a thin layer of solid core PE. This outer thin layer can prevent moisture intrusion from the start of production on the protection of cable electrical performance, this design is especially important for the opening of the outer conductor leaky cable. In addition, the insulating layer is formed by a thin layer of tightly wrapped within the inner conductor, and further improve the mechanical stability of the cable. Moreover, the thin layer contains a special stabilizer that ensures compatibility and copper, but also ensures the long-term life of our cables. Within the appropriate choice of sheet material, you can achieve satisfactory performance, such as: moisture, bonding and stability.
This multilayer insulation design (thin layer - foamed layer - outside TLC) can be obtained at the same time excellent electrical performance and stability of the mechanical properties, thereby improving the long-term life and reliability of our RF cable.
The most common outdoor cable jacket material is black linear low density polyethylene, which is similar to the density of the LDPE, HDPE power cable, but with considerable strength. On the contrary, in some cases, we tend to use HDPE, it can provide better mechanical properties and performance of abrasion, chemical, moisture and different environmental conditions for the jacket.
UV-resistant black HDPE to withstand climatic stresses such as high temperatures and strong UV-induced. When emphasize fire safety cables should be used when halogen flame retardant materials. In the leaky cable in order to reduce the spread of fire, may be used between the outer conductor and jacket with fire retardant, so easily melted insulating layer remains within the cable.