Understanding PIM Testing (Part 1 of 2)

What is PIM?

Today’s mobile handset users expect consistently high throughput from their devices and are always pushing current networks to their limit. PIM is a series of unwanted but related frequencies that occur when two or more frequencies pass through a nonlinear device or junction. PIM is noise, interference and a quality indicator.

Causes of PIM

PIM shows up as a set of unwanted signals created by the mixing of two or more strong RF signals in a nonlinear device, such as a loose or corroded connector, or nearby rust. The strong signals normally come from transmitters sharing an antenna run, transmitters using adjacent antennas or nearby towers with conflicting antenna patterns. Here is a list of prime suspects when you have a PIM problem:

• Mechanical Considerations
• Tunneling Effects
• Rusty Bolt Effect
• Ferrimagnetic Materials
• Surface Effects
• Time Dependency of PIM Sources

Solutions & Preventions of PIM

In addition to attending the manufacturer’s installation training courses, follow these best practices when working with precision RF cables and connectors:

• Inspection – Inspect the connectors for physical damage and looseness. Any damage may allow micro arcing or the diode effect to occur, causing some level of PIM.
• Cleaning – Minimize PIM by keeping the connectors clean. Use a cotton swab, low-pressure air, Isopropyl alcohol, and a toothpick to clean connectors before re-assembly.
• Torque – Tighten connectors to the proper (and required) value to avoid gaps and damage to the center connector.

At CTS Cabling, our sole focus is the quality assurance of your network utilizing the latest testing techniques. CTS is committed to DAS and has invested over $100,000 in testing equipment used for DAS installations.

If you are looking for an experienced cable contractor for wireless network installation, CTS Cabling is highly knowledgeable in Distributed Antenna Systems (DAS) and PIM testing. To learn more about CTS Cabling and our innovative services, or to speak with an experienced cable contractor, call 877-685-2626 or contact us online.