RF Cable Introduction
In addition to frequency range, standing wave ratio, insertion loss and other factors, the correct selection of RF cable components should also consider the mechanical characteristics of the cable, operating environment and application requirements, in addition, cost is also an ever-changing factor.
In this paper, the various indexes and performance of RF cable are discussed in detail. It is very beneficial to know the performance of the cable for selecting the best RF cable assembly.
Cable selection
Rf coaxial cable is used to transmit RF and microwave signal energy. It is a distributed parameter circuit whose electrical length is a function of physical length and transmission speed, which is fundamentally different from low frequency circuit.
Rf coaxial cables can be divided into semi-rigid and semi-flexible cables, flexible braided cables, and physically foamed cables. Different types of cables should be selected for different applications. Semi-rigid and semi-flexible cables are generally used for interconnection within equipment; In the field of testing and measurement, flexible cables should be used; Foamed cables are often used in base station antenna feed systems.
Semi-rigid cable
As the name suggests, this type of cable is not easily bent into shape. The outer conductor is made of aluminum or copper tube. The RF leakage is very small (less than -120dB) and the cross-talk caused in the system is negligible.
The passive intermodulation characteristic of this cable is also very ideal. If you want to bend it into a certain shape, you need a special molding machine or a manual mold to do it. Such a troublesome processing technology in return for very stable performance, semi-rigid cable using solid polytetrafluoroethylene material as the filling medium, this material has very stable temperature characteristics, especially under high temperature conditions, has very good phase stability.
Semi-rigid cables cost more than semi-flexible cables and are widely used in various RF and microwave systems.
Flexible braided cable
Flexible cable is a “test grade” cable. Compared with semi-rigid and semi-flexible cables, the cost of flexible cables is very expensive, because flexible cables are designed to take into account more factors. Flexible cable should be easy to bend many times and still maintain the performance, which is the most basic requirement as a test cable. Soft and good electrical indicators are a pair of contradictions, but also lead to the cost of the main reason.
The selection of flexible RF cable components should consider various factors at the same time, and some of these factors are contradictory, for example, coaxial cable with single-strand inner conductor has lower insertion loss and amplitude stability when bending than multi-strand coaxial cable, but the phase stability performance is not as good as the latter. Therefore, the selection of a cable component, in addition to the frequency range, standing wave ratio, insertion loss and other factors, should also consider the mechanical characteristics of the cable, operating environment and application requirements, in addition, cost is also a constant factor.
Post time: Apr-19-2023
