RF Cable Specifications
Radio frequency (RF) cables are essential components to countless RF systems, ranging from basic transceiver devices to communication systems present in aviation applications. RF cables known as test cables are important for the optimal transfer of power signals between two equipment pieces, devices, or to a transmitting antenna. To ensure that such devices function as intended, it is important to choose the right type of cable with specifications that are compatible with certain applications and systems.
Impedance is a major aspect of RF cable operations, the impedance of a line is determined by calculating the ratio of its voltages and the current of a wave propagating along it. There are many factors that affect impedance, those of which include the conducting material of the cable, the dielectric, and the material’s geometry. When discussing impedance, one would use the SI unit Ohm.
Frequency range is another important factor to consider, and frequency ranges are often limited by the construction material of the cable. The most optimal frequency will often vary based on the application in question. For more professional RF test applications, higher accuracies are required, and thus high end cables are preferred.
When accuracy is an important specification for a particular application, phase stability is a characteristic that one should pay attention to. When using standard RF cables, phase stability should be fairly optimal, and calibration should ensure that the phase difference is unaffected. When placed in a transmission system, phase difference can affect the system’s efficiency.
When discussing attenuation, one is referring to the signal loss as a result of cable losses. Generally, higher loss leads to less efficiency, thus it is important to control such factors as possible. For RF lab testing applications, low-loss standard RF cables are most suitable for device measurements.
Power specifications refer to the power range that an RF cable operates on, and there are a wide variety of types that accommodate different needs. For low power transmission, low power cables are best. Meanwhile, transmission system equipment and testing devices may necessitate high power cables. When procuring high-end cables, such components may be capable of managing power upwards of a few kilowatts.
If the application in question features extreme temperatures or temperature fluctuations, the cable in question should be able to withstand such factors while maintaining efficiency. Coaxial cables can often differ in performance when shifting between high and low temperatures, potentially skewing testing or other procedures. Generally, high temperature application cables are those that feature a dielectric, inner conductor, outer layer, and connector assembly.
While many of the aforementioned characteristics can affect general performance, the physical dimensions of the cable itself can also determine whether or not the particular component is suitable for a given space. Physical dimensions generally cover the connector type, size, shape, diameter, and length. Flexibility is somewhat similar, such qualities determine the ability for RF cables to be bent around corners and right spaces.