Coaxial line is a lead system composed of two coaxial cylindrical conductors. It is a broadband microwave transmission channel filled with air or high-frequency medium between the inner and outer conductors. So, let’s learn about the structure and classification of coaxial lines!

1. Coaxial line structure

Sheath, that is, the outer layer is protected by an insulating layer. Outdoor cables should use black polyethylene with excellent climate characteristics. Indoor user cables should use light-colored polyethylene for aesthetic reasons. The outer conductor (shielding layer) and the outer conductor of the coaxial cable play a dual role. As a wire in the transmission circuit, it transmits low levels and has a shielding effect. The outer conductor usually has three structures.

1) Metal tubular shape. The structure is made by winding and welding copper or aluminum strips lengthwise, or by extruding seamless copper tubing. Although this structure has shielding performance, it has poor flexibility and is often used in trunk cables.

2) Aluminum-plastic composite tape is longitudinally wrapped and overlapped. This structure has good shielding effect and low manufacturing cost. However, since the outer conductor is a round tube with longitudinal slits, electromagnetic waves will leak from the slits, so please be careful when using it.

3) The combination of net and aluminum-plastic composite tape longitudinal wrapping. It is developed from a single braided structure and has the characteristics of good softness, light weight, and reliable joints. Experiments have proved that the use of reasonable composite structures can greatly improve the shielding performance. Currently, this structural form is widely used.

2. Classification of coaxial lines

1. According to the impedance, it can be divided into 50 ohm (RG8/RG58/RG-11), 75 ohm (RG-11), and 93 ohm (RG62).

2. According to the diameter of the cable, it can be divided into thick cable and thin cable.

Thick cables are suitable for relatively large local networks due to their thick diameter and poor elasticity. The standard distance is long, and the transmission distance reaches 500 meters. Due to its high reliability, there is no need to disconnect the cable during installation, so the computer's network access position can be flexibly adjusted as needed. However, thicker cable networks require the installation of transceiver cables, which is difficult to install and therefore expensive overall. The installation of thin cables is relatively simple and low-cost, but the cables need to be cut during installation. Because basic network connectors (BNC) need to be installed at both ends and then connected to both ends of the T-shaped connector, there is a danger of defects caused by too many connectors. This is a common fault that occurs in currently running Ethernet networks. one.

3. According to the transmission mode, it can be divided into baseband coaxial cable and broadband coaxial cable.

Coaxial cable is used for data transmission. Within 1Km, the speed can reach 1-2Gb/s. Broadband coaxial cable: 300MHz~750MHz analog signal transmission (FDM), one of the main differences between broadband systems and baseband systems is that because the coverage area of the broadband system is wider, analog amplifiers are required to periodically strengthen the signal and The signal is amplified.

4. According to different uses, it can be divided into cable TV, wireless access feeder, and broadband data network.

The above introduction is the structure and classification of coaxial lines. If you need to know more, you can contact us at any time!