Doing a good job with every meter of cable

Coaxial cable(Coaxial Cable) refers to two concentric conductors, and the conductor and shielding layer and share the same ax is of the cable. Its basic structure is divided into four layers from the inside out: the centre of the copper wire(single stranded solid wire or multi-stranded stranded wire), plastic insulator,foil or mesh conductive layer and cable sheath. The central copper wire and the mesh conductive layer form the current loop. The name is given to the coaxial relationship between the central copper wire and the foil or mesh conductive layer.

Coaxial cableis a common signal transmission line, the centre of the conductor is to transmit high-level signals, by the insulation material; insulation material outside the coaxial with the copper core of the barrel of the thin layer of metal, transmitting low-level, and at the same time play a shielding role.Coaxial cable can with stand the maximum power, then its characteristic impedance in the 60 Ω best; if you want to withstand the highest voltage between the inner and outer conductors of the maximum power transmission, the characteristic impedance of the cable should be 30 Ω; if you want the signal in the coaxial cable transmission of the loss of the smallest, the cable's characteristic impedance of the best for the 76.5 Ω. Need to be coaxial line conductors under a certain temperature rise in the maximum power transmission,the cable's characteristic impedance The best for 36.38 Ω; in the use of power,such as transmitter feeder, mainly from the power and voltage considerations ofthe performance of coaxial cables, and thus the characteristic impedance of such cables more than 50 Ω, in order to have a better power capacity and voltage performance. Factory production of coaxial cables are mainly 50Ω and 75Ω two kinds of characteristic impedance, in the selection of coaxial cable,must be distinguished, do not confuse. In addition, a variety of cable headsand cable sockets, etc. also have 50 Ω and 75 Ω points, the same can not beused by mistake, otherwise it will produce reflections.

Coaxial cables can be divided into two basic types, baseband coaxial cables (50Ω) and broadband coaxial cables (75Ω). The former are used for transmitting digital signals, such as base station feeders and GPS antenn as, while broad band coaxial cables are used for transmitting analogue signals, such as Closed Circuit Television (CCTV) cables and connecting cables for surveillance.

Nowadays,with the continuous development and maturity of optical fibre cables, copper coaxial cable due to the cost of materials and transmission efficiency andother issues gradually lose their advantages in the communications industry is known as ‘light into the copper back’. However, due to the cable electromagnetic field closed between the inner and outer conductor, so the radiation loss is small, by the outside world interference impact is small,coupled with the installation and use of relatively simple and convenient, so there are still occasions for its use.

Then in the performance of coaxial cable, capacitance, characteristic impedance, return loss, attenuation constant and other response transmission performance parameters are particularly important. In turn, is also to consider the design of coaxial cable using how the conductor material, insulation material and shielding material structure of the most important basis. At the same time in the production process is also the reason why we need to control.

In the coaxial cable production process factors affecting product performance is intricate and complex, roughly summarised. Because there are some online monitoring means in the production process, such as online calibrator, pressure monitor, water capacitance monitor, spark detector, surface defect detector,etc., can be observed directly in the production process, indirectly determinethe quality of the cable in the manufacturing process. Coaxial cable performance determining process is the core wire extrusion process, so it canbe said that the quality of the core wire determines the quality of the finished product, the quality of the core wire will not be covered up becauseof the processing of the latter will only be magnified.

Core wire extrusion first conductor to keep clean and round, if necessary, in the conductor also need to pull and ultrasonic cleaning, to keep the surface smooth and clean, at the same time, tension control, preheating to ensure that the conductor and insulation between the good bonding. Insulation extrusion in the selection of suitable insulation materials to ensure that the product meets the design requirements, of course, need to ensure that the insulation of the higher concentricity the better, the more stable insulation diameter the better, inorder to ensure that you can get a stable water capacitance, the most ideal state needs to be controlled at ± 1.0pF / m so as to obtain a better line arimpedance and return loss. In the use of physical foam, a reasonable ratio of substrates, mixed with a certain proportion of nucleating agent is a goodpremise of the foaming process, of course, need to pay attention to the controlof nitrogen in let pressure and flow, to ensure that the bubble holes of thefine and dense, foam stability, wire diameter size is consistent, is a good coaxial core line of the key. In this process, especially pay attention to the purity of nitrogen, gas injection needle hole size selection control flow,different wire diameter different foaming requirements of the line in the production of different sizes need to be replaced with a different size of the gas injection needle.

Do a good job of coaxial core, in the shielding process should also pay close attention tothe details of the process, such as the stability of the core line of the core line of the braiding of the release tension, aluminium foil longitudinal wrapping of the wrapping of whether the flat, overlap rate is up to there quirements of the braiding pitch, the braiding of the spindle of the reasonable tension, as well as the hauling process of collecting the line whether there is a twisted or irregular stacking and so on, may cause the performance of the coaxial change. The shielding effect of coaxial cable can be measured by the shielding attenuation, which affects the shielding attenuation of physically foamed polyethylene coaxial cable mainly depends on the following factors:

Several factors of shielding attenuation

1, The lap width of aluminium foil is not less than 5mm.

2, aluminium layer thickness is recommended to increase to more than 15µm, or even higher to30µm.

3, reasonable arrangement of attenuation, echo, shielding relationship, the former and the latter 2 contradict each other, in the attenuation of qualified conditions to reasonably reduce the degree of foaming, to improve the shielding effect and echo are beneficial.

4, the quality of aluminium foil should be good, especially good flexibility, after avariety of bending without cracks.

5, woven longitudinal package process to improve, so as to avoid the middle of the tape folds, the formation of gaps or reduce the lap width, causing leakage.

6,reasonable weaving density, generally 40% can be. High density has a little compensation for shielding, but if the braiding density is too high, at high frequencies, the high density braided cable makes the ‘side frequency difference’ increase, thus amplifying the difficulty of compensation, the cable performance impact.

Although the use of coaxial cable in our country is decreasing year by year, but because of the reliability of transmission, installation and use is also more convenient,in many occasions or irreplaceable existence. In addition, in some developing countries and regions, coaxial cable still has a large market.

Tianjie seriously do a good job on every metre of coaxial products, control every key point of quality, serve the needs of customers, win the trust of the market forTianjie coaxial products, step by step to do fine and strong.