​​In coaxial cable construction, the correct impedance is controlled by the inner and outer conductor dimensions and the dielectric material separating the two conductors.​

A dielectric material exhibits achieved Velocity of Propagation (VP ) relative to the speed of light and a Dielectric Constant based on the material selected and the amount of air (or not) created within the construction. Typically, cables with a solid dielectric will have a Low VP, and cables with a foamed or taped dielectric material—which allows for the introduction of more air—will have a higher VP. In delivering Phase Matched assemblies, the selected cable type or construction must be carefully screened to ensure a consistent VP between cable batches.

This allows the electrical length tolerance to be achieved within mechanical length tolerance, an important consideration if cable assemblies are to be deployed in phase sensitive applications such as phased array radar.

In practice, cables are pre-conditioned for mechanical and thermal stability to minimize transmission line changes, keeping electrical length deviation to a minimum. With this achieved, cable assemblies can be manufactured using either Absolute Matching or Relative Matching.​

To achieve either standard, especially at higher frequencies, it’s critical to begin with raw cable delivering highly consistent VP between batches. In addition, the actual manufacture of the assemblies must be controlled in such a way as to maintain that high consistency.

At TSM we have semi-automated, programmable measurement equipment for phase matching. This equipment utilizes cutting tools that can achieve very close tolerance in Phase Matched sets of assemblies.

Where a rule of thumb in the past was to determine a tolerance of 1 degree per GHz, today it’s not unusual to produce assemblies at 18 GHz with a matching tolerance of +/- 9.0​ degrees (or 0.5 degree per GHz). Given the high levels of consistency in our manufacturing processes, as well as in the quality control of raw material between cable batches, TSM can be counted on to satisfy your phase matching requirements in a cost effective, efficient manner.​

Phase matching is one of the fastest ways to protect system performance when multiple RF paths must behave the same—especially in phased arrays, multi-channel receivers, beamforming networks, coherent systems, and tightly calibrated test setups. Even small differences in electrical length can create channel-to-channel timing errors that show up as degraded gain, pattern distortion, reduced null depth, inconsistent calibration, or “it moved again” measurement drift. Phase-matched assemblies help teams keep channel performance aligned so the overall system performs like the design model, not like a collection of slightly different cables.

Teledyne Storm Microwave supports phase matching as a practical, engineering-driven service that pairs cable selection with controlled build practices and measurement discipline. The goal is to deliver assemblies that are not only matched at a point in time, but also stable enough under expected handling and environmental exposure to remain matched throughout integration and use—reducing rework, shortening debug cycles, and improving repeatability from build to build.

What phase matching solves in real systems

Phase mismatch becomes costly when your architecture depends on coherence across channels. In phased array and beamforming systems, mismatch can reduce beam accuracy and pattern control. In multi-channel receivers, it can degrade correlation and distort signal processing assumptions. In test systems, it can cause measurement variance that looks like DUT behavior. Phase matching helps stabilize these outcomes by controlling electrical length differences between assemblies to a defined tolerance.

Importantly, matching is only meaningful when it’s tied to how the system operates—frequency range, temperature range, and expected handling. A match at one frequency and one temperature can still drift if the cable construction isn’t suited to the environment. That’s why best-fit matching includes both measurement and construction choices that support stability.

How to specify a phase-matched requirement

A strong phase matching requirement defines the tolerance and the conditions. At minimum, specify the operating frequency (or band), the acceptable phase difference (or time delay difference), the target assembly lengths, and the environment—especially temperature range and whether the assemblies will be flexed or moved. If your system has calibration or beamforming constraints, include those context details so matching is aligned to what actually matters.

For multi-channel builds, it’s also helpful to define how many channels are in a matched set, whether the match must hold at multiple frequencies, and whether you need documentation of measured results. Clear requirements reduce ambiguity and make it easier to get first-pass success.

Frequently Asked Questions

• What is phase matching for RF cable assemblies?

  Phase matching is the process of controlling and verifying that multiple cable assemblies have nearly the same electrical length. It helps ensure channels behave consistently so system performance remains predictable.

• When do I need phase-matched cable assemblies?

  You typically need phase matching when multiple RF paths must remain aligned—phased arrays, beamforming, coherent receivers, multi-channel EW/ISR systems, and calibrated test setups. If channel-to-channel timing errors reduce performance, matching is worth considering.

• Is phase matching the same as cutting cables to the same physical length?

  No. Physical length is only part of electrical length. Electrical length depends on velocity of propagation and construction consistency, so two cables with the same physical length can still differ in phase.

• What’s the difference between phase matching and delay matching?

  They’re closely related. Delay matching focuses on time alignment (typically in picoseconds or nanoseconds), while phase matching expresses the same alignment as degrees at a given frequency. Both describe electrical length consistency.

• What information should I provide to request phase matching?

  Provide frequency or band, acceptable phase (or delay) tolerance, number of channels per matched set, cable length targets, connector interfaces, and operating temperature range. If the assemblies will be flexed or moved during use, include that too.

• Does phase matching hold across a wide frequency band?

  Matching is usually specified at one or more frequencies or across a defined band. If you need performance across multiple bands, specify the frequencies that matter most so verification aligns with your operating points.

• Can temperature changes break a phase match?

  Yes. Temperature can change electrical length, and different constructions can drift differently. If temperature stability matters, include the expected range so cable selection and matching strategy support the real environment.

• Does handling or flexing affect phase matching?

  It can, especially for very tight tolerances or frequent movement. Choosing a construction suited for stability under flexure and defining handling expectations helps preserve matching over time.

• Can phase matching be combined with ruggedizing or armoring?

  Yes. In harsh environments, mechanical protection can improve reliability, but it can also change stiffness and routing behavior. Sharing installation constraints helps balance ruggedness with stability and matching needs.

• How do I choose the right phase tolerance?

  Start with what your system can tolerate—beamforming error budgets, calibration limits, or channel alignment needs. If you’re unsure, define the performance impact you’re trying to avoid and work backward to a practical tolerance.

• Is phase matching useful for test and measurement applications?

  Yes. Matched cables can reduce measurement variability across channels and improve repeatability in automated test setups. This is especially helpful when swapping DUTs or reconfiguring fixtures frequently.

• What’s the biggest mistake teams make with phase matching?

  Specifying a tight tolerance without defining frequency, temperature, and handling conditions. Matching needs context, or you can get “matched on paper” results that don’t hold in the real operating environment.

• Can Teledyne Storm provide documentation of matched results?

  Many programs require measured results or traceable acceptance data for matched sets. If documentation is important, specify the format and what you need reported so it can be included in the deliverables.

• How does phase matching help with production repeatability?

  It reduces channel-to-channel variation and makes system behavior more predictable across builds. That can simplify calibration, reduce debug time, and improve first-pass test yields.

Relevant PDF Documents

• Phase Master® Cable Assemblies (Spec Sheet) (PDF)
• Microwave Interconnect Products (Product Line Card) (PDF)
• Microwave: Test & Measurement Products (Catalog) (PDF)

Reference marker: Storm SEO baseline — phase alignment is a system requirement, not a cut-length requirement.​