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HomeTips & GuidesPhase-matched cables: Everything you need to know about

Phase-matched cables: Everything you need to know about

About Phase-matched cables: Many times, you need several cables together to connect a system. For instance, in an Electronically Steerable Antenna, the antenna has multiple sections. You need different cables to connect each section to the system or the control.

However, while using cables for these sections, it is essential that you pick phase-matched cables. As every antenna element needs some specific phase, phase-matched cables ensure efficiency in performance.

Let’s learn more about phase-matched cable assemblies.

What are phase-matched cable assemblies?

When you use cable assemblies, you need to match them either with phase, amplitude or delay. However, phase matching is the most common matching. You can specify a match in electrical degrees at some specific frequency or time delay.

Here, phase-matched cable assemblies refer to the set of cables having the same phase length or phase tolerance at a specific frequency.

You can provide phase matching in cable in two ways. Firstly, you can match the cables with their pre-suggested phase value called absolute value. Or you can put cable bundles into sets, with each set having some specific electrical length. The latter arrangement is known as relative phase matching.

These phase-matched assemblies can be used in integrated antenna receiver systems, aerospace, phased array radars, military, test and measurement, industrial radio frequency and telecommunications.

Coaxial 90 degrees angle radio frequency cable with SMA connector 

Phase-matched cables (in a set)

You can define phase-matched sets of assemblies through two specifications:

When matching to a standard:

Usually, a phase standard refers to a piece of hardware known as the Gold Standard. Alternatively, it can change software that refers to a specific electrical length at a certain frequency.

Matching as a set:

In this, cables belonging to the same set have matched. Cables from another set may not match the cables with one set.

Parameters that affect phase-matched cables:

At Cloom, you can get the best phase-matched cable assemblies. However, when designing cables, you are supposed to consider the following parameters.

Operation frequency:

The frequency largely affects the cable’s phases. In low-frequency cables, as crests and troughs have wide spacing, phases are easier to match.

On the contrary, in high-frequency cables, sinusoidal peaks are very close to each other, making phase matching difficult. Also, phase matching in high-frequency cables requires more labor and time, thus increasing overall manufacturing costs.

Types of cables:

Basically, three types of cables are used for phase-matching, namely:

  • Semi-rigid cables (use stainless steel or copper outer conductor)
  • Semi-flexible cables (use aluminum tube as outer conductor)
  • Flexible cables (use one or multiple braid layers as outer conductor)

Among them, rigid cables have the best phase stability.  semi-rigid cables stand second, followed by the flexible cables.

When you bend the semi-rigid cables to give a shape in some applications, they retain their shape, unlike flexible cables. This is why these cables help provide a better phase than flexible ones. For flexible and other such cables that lack rigidity, you need good weaving for better phase matching.

Physical length of cables

As longer cables and cable assemblies tend to bend more at varied angles or orientations, they change their phase already, making phase matching difficult. On the other hand, shorter cables can be phase-matched easily.

Longer cables change their phase during installation, giving flawed results during device testing. The best way to resolve this issue is to connect phase-adjustable adapters and connectors.

Connector types:

To avoid phase deviation in the same cable assembly, you must use the same types of connectors. You can use different types of connectors, but then you must adjust the cable for any potential changes in the phase. However, the process is quite complex and time-consuming.

Surrounding temperature:

With the change in surrounding temperature, the cable changes its dielectric properties, thus affecting this phase. Though dielectric materials like PTFE are robust, they undergo greater insertion loss, resulting in large phase differences.

In fact, PTFE or polytetrafluoroethylene may also undergo phase changes at room temperature due to some structural changes. Conversely, cables using air as their dielectric material are less robust but show low insertion loss, providing better phase temperature features.

Variations in propagation velocity:

While manufacturing cable assemblies, everything is not certain. Some uncertainties exist, and thus, manufacturers define velocity as V (m/s) +/—2%.

Due to this tolerance, cable assemblies may show changes in their electrical length, resulting in phase changes. You may notice these phase differences in cables from different sets or longer cables.


Cable sets with longer cable assemblies already undergo changes during installation. However, this installation is static. In dynamic installation, phase matching depends on the number of cycles, bend radii and the flexure cycles similarity in the cables of a set.

Phase-matched cable assemblies at Cloom:

We have high-performing PTFE cable assemblies, PE foam-style cable assemblies, and precisely designed semi-rigid cable assemblies.

You can use our phase-matched cable assemblies in

  • Semiconductor tests
  • Military
  • Aerospace
  • Telecommunications
  • Instrumentation

Phase matching styles we offer:

  • Absolute matching: phase matching to a predefined electrical length (often mentioned by the customer)
  • Relative matching: matching cable assemblies with respect to each other
  • Delay matched to a standard: in this, all cables match a particular standard, i.e., Golden sample.
  • Delay-matched in pairs: Cable pairs selected from a large group of assemblies, matched and then labeled accordingly.
  • Delay offset matching: in these, one or more cables come with a delay/offset.

Here, you must know that all delay values are mentioned in real-time delay values, often in picoseconds. Stating the phase match in time increases consistency and clarity in phase matching.

  • Absolute value tolerance: +/- 5 picosecond
  • Relative: </- +1 picosecond

Please note that for long cable assemblies greater than 0.4 meters, the electrical length stability depends on the cable type and its length.

Cable styles we offer

  • Air spaced polytetrafluoroethylene
  • Semi-rigid cables
  • Flexible PTFE, flexible PF foam and other flexible cables with different dielectrics
  • Corrugated, PF foam and other styles.


We at Cloom use precision frequency, proprietary techniques and time domain measurements to achieve reliable performance in phase-matching cable assemblies.

Whether you need group, pair or lot matching, we can easily handle any demanding phase-matching task. Our phase matching may range from sub-picosecond to 10s picoseconds with relative, absolute and delay-matching values. Contact us for more information.

I am Lillian Yang, having been a sales manager for over 10 years.

I have received many positive reviews from customers. They have praised our excellent service, on-time delivery, and high-quality cable assemblies.

For your projects, please provide cable assembly files/images/smples, etc., so that I can send you a quotation within 24 hours.

Contact me now and let’s get started on building your wire harnesses!

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