PIM Limit For RF Connectors

May 04, 2019
PIM Limit For RF Connectors

Acceptable PIM levels are usually set by the site or device owner. These numbers will be based on their specific frequency bands and device scenarios. Antennas installed 10 years ago may not have considered PIM performance, so setting a PIM level greater than -80 dBm / 123 dBc is unrealistic because few people can measure it. It is even less likely to consider the PIM specification when designing a network.

New antennas and related components should be shipped with the factory to provide factory test results. Any tests performed on site should be closely related to these numbers.

It is important to remember that customers must specify PIM requirements, including specific test parameters and test power during the procurement process. It is difficult to claim a warranty for a specification that has never been requested.

Using a 2 x 20 watt PIM tester, the typical PIM guide for an antenna system is between -150 dBc and -160 dBc. This is basically equal to the maximum PIM level of -107 dBm. New antenna systems should normally be at the lower end of the range, while older antenna systems should at least make the upper end of the range.

The standard number for system-level site PIM testing around the world is the pass level of -97 dBm / 140 dBc. This is not difficult to achieve at the scene. Once the -95 dBm / 138 dBc region is exceeded, the PIM number is typically significantly increased, and measurements at -125 dBm / 168 dBc are also common. As the overlap of LTE services begins now, the pass-through value of -97 dBm / 140 dBc may not be sufficient. Therefore, it is wise to use a PIM test that exceeds the specified receiver sensitivity level (usually around -107 dBm / 150 dBc).