PIM
Understanding PIM
PIM occurs at metal-to-metal contacts, corroded surfaces, loose connections, contaminated connectors, and ferromagnetic materials in the signal path. The non-linearity at these junctions creates intermodulation products at frequencies f = m*f1 + n*f2.
PIM is measured in dBc relative to the carrier power, with typical specifications requiring PIM below -150 to -160 dBc for two +43 dBm carriers. Low-PIM components use non-ferrous materials, controlled torque connections, and silver or white bronze plating.
Frequently Asked Questions
Why is PIM a problem?
PIM products can fall within the receive band of a co-located system, raising the noise floor and degrading receiver sensitivity, especially in cellular base stations.
How is PIM prevented?
Use non-ferrous materials, maintain clean connections, apply proper torque specifications, and avoid dissimilar metal junctions in the RF path.