Radio frequency coaxial cable classification

Radio frequency coaxial cable classification

The structure of radio frequency cables is diversified and can be classified in different ways.
1. Cable structure classification
1) coaxial radio frequency cable
Coaxial RF cable is the most common structural mode. When the inner and outer conductors are in a concentric position, the electromagnetic energy is limited to the medium propagation between the inner and outer conductors, so it has significant advantages, that is, less weakening, high shielding performance, use frequency bandwidth and performance stability. Usually used to transfer RF energy from 500 kHz to 18KHz.
At present, there are two types of common RF coaxial cables: 50Ω and 75Ω RF coaxial cables. The characteristic impedance 75Ω RF coaxial cable is usually used in CATV network, so it is called COTV cable, and the transmission bandwidth is up to 1GHz. The current CATV cable is currently being transferred to 750MHz.

2) Symmetrical RF cable
The symmetrical RF cable track has an open electromagnetic field, and due to the high frequency of the radiated electromagnetic energy, the attenuation is increased, and the shielding is poor, and the influence of atmospheric conditions is usually rarely used. Symmetrical RF cables are mainly used for low radio frequency or symmetrical feeding.

3) spiral radio frequency cable
The conductor in a coaxial or symmetrical cable can sometimes be a spiral coil to increase the inductance of the cable, thereby increasing the wave impedance and transmission time of the cable. The former is a high-resistance cable, and the latter is used for a delay cable. If the spiral coils have different winding densities in the length direction, the cable can be varistorized.

2. Classification of Insulation Forms

1)physical insulated cables
All physical high-frequency dielectrics are filled between the inner and outer conductors of this kind of cable, and most flexible coaxial radio frequency cables use this form of insulation.

2)air insulated cable
In the cable insulation, except for a part of the solid medium that supports the inner and outer conductors, the rest is basically air. The structural feature of one conductor to another without passing through the middle layer. Air insulated cables have very low attenuation, which is a form of ultra-high frequency structure.

3)semi-air insulated cable
This type of structure is an insulation type between the above two types, and the insulation is also combined by air and solid dielectric, but from one conductor to another, it needs to pass through a solid dielectric layer.