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What is PIM in Telecom?

What are the effects of PIM in telecom?

February 2017

Many of us have experienced the inconvenience of noise or distortion while in the middle of a cell phone conversation, or even worsea dropped call. While we often assign this mishap to the provider or cell service in certain locations, sometimes these are issues with cell towers where the signals are generated. One cause of such distortion is PIM, or passive intermodulation, which we will be explaining in this Insights post.

As the demand for higher frequencies and bandwidth grows, so do the issues of wireless interferences. LTE and 5G networks are especially susceptible to PIM, due to higher-powered signals and the use of multi-band or wide band antennas. PIM leads to more static and reduced coverage and is very costly to the service provider in terms of physical costs to have maintenance on the tower, as well as the potential costs of losing customers due to unreliable cell service.

What is PIM?
At a basic level, PIM is the result of unwanted signals created by mixing of two or more frequencies in a non-linear passive device. These new signals interfere with and distort the original signal passing between two wireless systems. It can create signal interference in any wireless system. To ensure reliable communications performance, PIM distortion must be limited or eliminated. 

What causes PIM?
A multitude of outside influences can cause PIM, and the list below names some of the most common ones. PIM is primarily caused by imperfections in the transmission channel coupling onto another channel, more specifically non-linearity in the transmission line. Poor or bad electrical contact as well as bad design are some of the major sources of non-linearity that can create PIM. Therefore, some of the biggest contributors to PIM distortion are the cable assemblies and connectors utilized. The following factors play an important role in the performance of the system.  

  • Loose connectors
  • Improper contact force/torqueing
  • Materials used
  • Contamination of plating
  • Coating composition
  • Environmental issues (temperature, pollution, weather)
  • Vibration and shock
  • Magnetic materials
  • Corrosion or rust
  • Metal objects
  • Outside objects, such as light posts

Low PIM Interconnect Components
Low PIM components are critical when building wireless telecommunication networks. To ensure a good transmission line, the interconnect system from the design, materials and process related to implementation must be addressed to reduce or eliminate PIM. Radiall specializes in low PIM connectors, cable assemblies and microwave components. The primary connector interfaces available are NEX10, 4.3-10 and DIN 7/16. Furthermore, Radiall products go through rigorous testing to ensure excellent PIM performance.

Radiall has years of experience and expertise in manufacturing low PIM products for the telecom and test and measurement markets. Click on the links below to learn more.

Low PIM Switches

Low PIM Connectors