Analysis of RF test cable

The main technical basis for selecting RF test cable for a certain purpose is its electrical performance, mechanical performance and environmental characteristics. In some environments, fire performance is also important. All these properties are related to the structure and materials of RF test cable.

The main function of RF test cable is to transmit signals. Therefore, the structure and materials of RF test cable should ensure good transmission characteristics throughout the service life of the cable, which is very important and will be discussed in detail below.

1. Inner conductor

Copper is the main material of inner conductor, which can be in the following forms: annealed copper wire, annealed copper tube and copper clad aluminum wire. Generally, the inner conductor of RF test cable is copper wire or copper clad aluminum wire, while large cables use copper tube to reduce the weight and cost of RF test cable. The outer conductor of large cable shall be embossed, so as to obtain good enough bending performance.

2. Outer conductor

The outer conductor has two basic functions: the first is the function of circuit conductor, and the second is the function of shielding. The outer conductor of leakage RF test cable also determines its leakage performance. The outer conductors of coaxial cable and super flexible cable are welded by rolled copper tube. The outer conductors of these RF test cables are completely closed and the cable is not allowed to have any radiation.

3. Insulating medium

RF test cable dielectric is far from just playing the role of insulation. The final transmission performance is mainly determined after insulation. Therefore, the selection of dielectric materials and their structure are very important. All important properties, such as attenuation, impedance and return loss, are closely related to insulation..

The unique multi-layer insulation (inner thin layer foaming layer outer thin layer) coextrusion process can obtain a uniform and closed foaming structure, which has the characteristics of stable mechanical properties, high strength and good moisture resistance. In order to maintain good electrical performance in humid environment, we specially designed a kind of cable: add a thin layer of solid core PE on the outer surface of foamed insulation layer. This outer thin layer can effectively prevent moisture intrusion and protect the electrical performance of RF test cable from the beginning of production. This design is particularly important for leaky cables with holes in outer conductors. In addition, the insulating layer is tightly wrapped on the inner conductor through the inner thin layer, which further improves the mechanical stability of the cable. Moreover, the thin layer contains special stabilizer, which can not only ensure the compatibility with copper, but also ensure the long service life of our RF test cable. By selecting appropriate inner thin layer materials, satisfactory properties can be obtained, such as moisture-proof, bonding and stability.

This multilayer insulation design (inner thin layer foaming layer outer thin layer) can obtain excellent electrical performance and stable mechanical performance at the same time, thus improving the long-term service life and reliability of our rf test cable.

4. Sheath

UV resistant black HDPE can withstand climate stress caused by extremely high temperature and strong UV. When emphasizing the fire safety of RF test cable, low smoke halogen-free flame retardant materials shall be used. In the leakage cable, in order to reduce the spread of fire, a fireproof and flame-retardant tape can be used between the outer conductor and the sheath to keep the easily melted insulating layer in the RF test cable.