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How To Choose Coaxial Cable

Jun 12, 2017

Coaxial cable and components of the many electrical parameters, such as operating frequency, VSWR, transmission loss, power capacity, shielding performance, intermodulation performance, impedance and so on. And we can according to this type of public electrical parameters to see how to choose coaxial cable. The following are the same as the "

1, the working frequency

Please note that the general cable connector type will limit the maximum operating frequency, such as BNC for the bayonet connection, can only work to 4 GHz; high reliability of the N-type general to 18 GHz; SMA type up to 26.5 GHz; The 2.92 mm connector is the most common. The following are the same as the "

2, VSWR

VSWR value is naturally the lower the better, the general industry common cable basic values are between 1.1 to 1.4. Money and wayward can also find VSWR <1.1 cable with. The following are the same as the "

But also need to pay more attention to VSWR frequency flatness in the entire frequency band, the cable is at a certain frequency there are more prominent spikes, if the spike unfortunately falls within the operating frequency range, the test results may not be so good ...

Tips: If the non-rigid cable, experienced engineers in the network with the cable test the performance of the cable when you can grasp the cable jitter about, if the VSWR curve is almost fixed or change is small, then the cable VSWR stability of the basic OK! The following are the same as the "

3, transmission loss

The manufacturer often uses the insertion loss per unit length (dB / m) to indicate the transmission loss of the cable. In general, the smaller the cable diameter loss, the lower the density of the smaller dielectric loss, the lower the lower the frequency loss. The loss is low, the cost is also up, so in accordance with the system at the highest frequency of the insertion loss and the actual minimum length required to choose the cable is the best way to make the best use. The following are the same as the "

With the above VSWR, the transmission loss of the full band consistency is also quite important to drop. Especially in the case of longer cable length, where possible, pro to try to avoid the possibility of peak attenuation. The following are the same as the "

4, power capacity

The general rated power is said to enter the average power Oh, the peak power capacity if not given separately, then you need to kiss according to the peak to compare. The following are the same as the "

The power capacity is related to its cooling capacity, and the final limiting factor is the maximum allowable operating temperature of the material in the cable. In general, the power capacity is inversely proportional to the transmission loss. You in accordance with the actual use of the maximum power to choose the security of the. Natural, high-power silver will spend more. The following are the same as the "

Tips: In special applications, high temperature and high altitude will affect the heat dissipation and reduce power capacity. In these special occasions, the pro can be converted in accordance with the correction formula provided by the manufacturer. The following are the same as the "

5, shielding performance

The shielding performance is mainly determined by the structure of the outer conductor of the cable. The following table shows the shielding performance of the different outer conductor structures.

So solid-state shielding is the best, this common in rigid or semi-rigid coaxial cable.

6, passive intermodulation (PIM) performance

In recent years due to the complexity of the communication system, passive components of the third-order intermodulation parameters are also valued. Many systems will require passive intermodulation indicators below -160 dBc, or even -165 dBc. While the general braided cable generally intermodulation index below -140 dBc. Therefore, in the high passive intermodulation index requirements of the scene, can consider intermodulation better semi-rigid and semi-flexible cable. The following are the same as the "

7, impedance

Impedance selection is relatively simple, the cable cable is generally the cable is almost 75Ω, the rest of the commonly used 50 Ω-based cable.