General Design Criteria: Intermodulation Distortion

Coaxial cable assemblies have often been viewed as linear components. But there are small non-linearities in the connectors and the cable/connector junctions, usually caused by thin-surface oxide layers at the connector junctions or by separation of current-carrying contact zones. There are some simple design rules to prevent intermodulation distortions:

• Use of semi-rigid cable in place of flexible cable.
• Use of a solid center conductor in lieu of a stranded one.
• Solder or weld the outer conductor to the connector body in lieu of crimping.
• Use high quality machined connector parts with a smooth finish.
• Ensure adequate and uniform plating thickness.
• Use connector interfaces with radial dimensions as large as possible.
• Ensure adequate contact pressure.
• Eliminate use of ferromagnetic materials (steel, nickel).