Insertion Loss

What is insertion loss? What is insertion loss formula and what causes insertion loss?

As more and more businesses search for high-speed, global IT solutions that maximize scalability, optical fiber infrastructures have become increasingly popular. Ever experienced loss of signal when you plug something in to a device? It's a frustrating phenomenon for anyone who has had it happened to them. In telecommunications especially network cable this can be an issue that affects the over all performance of cabling. All losses are not equal, and a loss can come in many forms, such as a power loss, connectivity loss, insertion loss, and even a return loss. This blog will discussing the significance of insertion loss.

What is Insertions Loss

Insertion loss is the loss of signal when traveling in and out of a given circuit or traveling into a component and out of the component. It is measured by the amount of power received before and after the insertion and the results of insertion loss are typically measured in decibels (dB).

Insertion loss in copper cable: In copper cable, insertion loss measures electrical power lost from the beginning of the run to the end.

Insertion loss in fiber cable: In fiber cable, insertion loss (also called optical loss) measures the amount of light lost from beginning to end. Many things can cause light to be lost: absorption, diffusion, scattering and dispersion.

Best Way to Test Insertion Loss

There are 2 best ways to test insertion loss. All these test types such as crosstalk and insertion loss cover different attributes of Ethernet cables. Some measure interference and some measure signal strength. This is why insertion loss testing is important.

  • DCM: For network cable the best way to test insertion loss is through a DCM testing machine. A DCM machine tests finished cable for various performance characteristics such as return loss, insertions loss, near end cross talk, propagation delay and many other tests. DCM is a testing method that is usually done on the manufacturing side as it looks to test the cables itself, without any additionally connectors.
  • Fluke testerUsing a Fluke tester is a portable hand held device that can be used to test Ethernet cables with RJ45's and keystone jacks attached to them. It's a great tool for installers to see the performance of the cable channel, including insertion loss.

What is Insertion Loss Formula

Insertion loss is measured using the formula below.


The end result is a numbered decibels (dB) at various frequencies with the cable.

Now if you're not the one for tackling math equations the good news is that testing devices will calculate this for you. Now that we have the formula ready to use let us see what results will look like.

Insertion Loss Results

For our primary example we will base our insertion loss test results from a DCM machine because our focus is the cable itself. The results shown below are based on a solid UTP cable up to 328 feet (100 meters).

The outputted results show the cable being tested up to 550MHz and passing the insertion loss test. For a DCM machine the results aren't listed as absolute  values so you'll see the graph from 0 to -60. The blue line is the mark where your cable will need to be and any results above the line are a pass.

How To Prevent Insertion Loss

Insertion loss is something we all want to avoid so what are some ways we can prevent this from occurring. Here are some best practices you can do to prevent insertion loss:

  • Use Quality Cable: This is one of the first things you want to be doing when you are installing cable. A high quality cable will be solid copper, use the right amount of materials and certified.
  • Keep Cable Clean: Make sure to keep all cable connectors clean, especially before and after installation and testing.
  • Limit Amount Of Links In Cable Channel: Using too many devices and connectors can cause your signal to deteriorate and worse, not work. Try to limit the amount of connectors on your cable path.
  • Proper Terminations: Bad terminations can actually be a cause for signal loss so make sure to double check that all you terminations are punched down and wired properly.
  • Use The Right Cable Type In The Right Situation: There's actually certain ways to use certain types of cable. Stranded cable should be kept shorter in length and solid cable should be kept under 328 feet (100 meters).
  • Plan Ahead:Realize that designing a smart network and investing in quality installation and materials upfront can actually save money long-term.
  • Avoid Field Terminations: Which are more susceptible to particle contamination and may result in less than acceptable polishing of fibers.


All in all, insertion loss isn't going to be the first thing you want to consider when installing cables but it's important to keep it in mind when you plan your cable runs, because the efficiency and integrity of your fiber-optic network can be greatly undermined by insertion loss.

LightOptics offers an innovative selection of fiber cables (SHOP NOW) , all of which have undergone insertion loss testing with results that can be easily verified on our website. Our support team is standing by for expert business solutions so you can create a reliable, quality fiber network for you and your clients.

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