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Adding Value to Your RF Semi-Rigid Cable Assemblies

17 February 2021

Having the proper guidelines in place for your RF semi-rigid cable assembly helps minimize cost, improve electrical performance, and increase reliability.

When designing a semi-rigid cable assembly, the complexity of the project can be very costly. Having proper guidelines in place can improve performance, increase reliability, and decrease the cost of most semi-rigid cable assemblies.

  • Minimize bend radius changes throughout the cable - single bend radius is best practice
  • Keep all bend radius under 180 degrees - radius bending causes change to the geometry of the tubular component and adds additional stress to the cable
  • Avoid bends directly behind connectors - allow as much straight length available prior to connecting cable to connectors
  • Prevent multiple cable bends near each other - can generate crosstalk or interference in data transmission
  • Do not exceed the bend radius defined for each type of cable - bend radius is the safe value that can prevent the cable from damaging or degrading its performance
  • Maintain loose mechanical tolerance (Smiths Interconnect’s recommendation is +/-0.01” and +/-5 deg.)
  • Large bend radius is preferred over small bend radius for best performance and reliability
In addition, most RF semi-rigid cable suppliers would request:
  • Frequency band
  • Cable and connector styles
  • Any electrical limits - insertion loss and/or phase match tolerance
  • Bend configurations
  • Drawings (full scale), 3D Models or STP files if available

Semi-Rigid Cable Assemblies

High frequency RF cable assemblies are available with a wide variety of flexible and semi-rigid cable types with space orbit qualifications and are well-suited for Satellite Payloads (GEO/MEO and LEO constellations), Deep Space Probes, Ground Antenna Networks and Space Robotic Systems. Semi-Rigid cable assemblies are available with either a copper or aluminum jacket, available with a selection of different platings and offer in 4 different diameters:(.047”, .085”, .141” & .250”).

Semi Rigid Cables for Space


  • Mode Free Operation 60 to 65 GHz
  • Superior Shielding Effectiveness
  • Phase Matched Sets Available (standard tolerance is ± one degree per GHz)
  • Light Weight & High Vibration Resistance
  • Stainless Steel Connectors Available
  • On-demand Solutions According to Customer Specifications
  • Subjected to Extensive Space Qualifications

In summary, cables assemblies might not be the most expensive parts of your RF system, but they can certainly cause a drop in performance, with consequent direct and indirect (reputational) costs if guidelines are not followed when designing them. Decades of experience have positioned Smiths Interconnect well – both in designing and delivering state of the art RF cable assemblies and harnesses specifically engineered to support the trends and technologies of the future.

For additional semi-rigid cable support please view our on-demand webinar: 5 Challenges RF Cables Face in the Space Market

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