RF Semi-Rigid vs. Flexible Cables: Key Differences

This article compares RF semi-rigid cables with flexible cables, highlighting the crucial differences between the two types used in RF wireless testing. Both are coaxial cable types, but their construction and applications differ significantly.

RF Semi-Rigid Cable

The semi-rigid cable features an outer conductor with a solid sheath of extruded metal, typically copper. The outer and center conductors are usually made of different materials. This construction makes the cable quite rigid and difficult to bend into the desired shape. Great care must be taken during bending to avoid damage.

The typical process involves:

1. Cutting the semi-rigid cable to the required size.
2. Bending it to the desired shape according to specifications and drawings.
3. Applying heat to the semi-rigid RF cable to expand the dielectric.
4. Attaching the desired RF connectors on both sides or either side, as needed for the system.

RF Flexible Cable (Semi-Flexible)

This type of coaxial cable utilizes a braided outer conductor, offering much greater flexibility compared to semi-rigid cables.

Here are some key characteristics:

• Lower Phase Stability: Flexible cables generally exhibit less phase stability compared to semi-rigid cables.
• Easier to Use: They are significantly easier to manipulate and route.
• Connector Attachment: Unlike semi-rigid cables that often require soldering, flexible cables typically use mechanical means to attach connectors, such as crimp-on or screw-on fittings.
• Improved Shielding (Sometimes): Coating the exterior braid with solder near the connectors can improve the shielding performance, making it closer to that of a semi-rigid cable.
• Bend Limitations: A notable drawback is that flexible cables have a limited number of bends they can withstand before performance degrades.

Key Differences Summarized