Coaxial RF Cable Assemblies

Koaxis manufactures small diameter coaxial RF microwave cable assemblies for high-performance applications such as High Frequency,  Phase-matched,  Delay Matched,  Bent Semi-rigid,  Test and Measurement Applications and more.

Bent Semi-Rigid

Fabricated Bent Semi-rigid

Semi-rigid coaxial cable is the preferred choice for improved isolation, a broader temperature range, and improved VSWR for Inside the Box applications. When bent to shape, semi-rigid maintains it's shape and performance even under shock and vibration.

Koaxis uses and stocks a large inventory of Mil-DTL-17 semi-rigid cable primarily from Micro-coax as the cable is drawn in straight lengths which reduces the need for additional labor to straighten the material.  With 5 different sets of equipment for bending semi-rigid available in-house;  including custom-made CNC bender,  dedicated quick-turn setups, and custom-made bend fixtures; Koaxis chooses the most cost-effective and fastest method for each cable to ensure an economical and readily available solution.

It is important to understand that semi-rigid is a drawn tube, typically available in plated or unplated Copper or plated Aluminum. It is not synonymous with hand-formable (aka Semi-fliex®) cable, which is typically a Tin-dipped Copper braided cable. Additionally, RG401, RG402, and RG405 are NOT synonymous with their respective 250", .141", and .086" diameters. M17/129-RG401, M17/130-RG402, and M17/133-RG405 are specific grades of bare Copper semi-rigid cable that are popular in space and airborn applications.

Custom Marked

Custom Marked

Koaxis offers a variety of custom marking options for your assemblies. Using state of the art printers, we create markers on heat-shrink tubing consisting of 1 or 2 lines of text. Whether you need multiple markers, colored markers, serial numbers, CAGE code or more, Koaxis can mark your assemblies.

When specifying cable markings,  Koaxis recommends the following best practice:

  • Specify Black print on White marker
  • Do not specify font size
  • Keep markers short
  • Be aware of cable diameter
  • Send us a spreadsheet
  • For Standard products with -MK suffix, specify marking requirements on your order



Delay-matching is similar to phase matching, but uses time delay measured in picoseconds, to match the cables. Our standard delay tolerance is ±1 picosecond for cable lengths up to 3 feet.  Tighter tolerances are possible, contact us to discuss.

We offer:

  • Relative delay matching in pairs, sets or groups of cables.
  • Absolute delay matching to a known standard.
  • Delay offset matching, making some cables shorter or longer by a specified amount.



  • Koaxis manufactures phase matched and delay matched cable assemblies; although related, they are not the same.
  • Delay is a time measurement, which we measure in picoseconds as our cables are usually short.
  • Phase is a measurement in degrees at a specified frequency.
  • Our standard phase tolerance is ± 0.3 degrees per GHz, or 5 degrees at 18 GHz.

Tighter tolerances are possible, contact us to discuss.


Phase-stable v Flexure

Koaxis is primarily a supplier of small diameter cable assemblies and thus does not have much of an offering for phase v flexure applications. We are actively working on a .047 diameter cable with improved stability with flexure.  As this product becomes available we will update this page. 


Phase-stable v Temperature

While PTFE is the workhorse dielectric in the RF / Microwave world because of its high dielectric strength and low dielectric constant, at room temperature it goes through a structural change known as the "teflon knee" .  This causes a significant shift in phase as it moves through this temperature zone.  We are currently supplying 3 flexible cables to address this temperature phase shift using a foam fluoropolymer dielectric.  See our low loss KF047P,  KF086P and KF120P cables.  

We will be introducing semi-rigid versions of this cable in .047, .086 and .120 sizes in the future.


Phase-Tracking v Temperature

When your application requires multiple signals to arrive at the receiver in-phase, you need a cable that provides consistent and predictable phase-changes as the ambient temperature changes.  Koaxis K-Flex 120 cable provides superior phase-tracking vs temperature without the high cost associated with phase-stable vs temperature cable.  Currently, in service in several array applications, K-Flex 120 provides outstanding low-loss and phase-tracking vs temperature performance from DC-40 GHz.