Passive Intermodulation testing catches interference sources at acceptance. The single most common cause of post-construction performance loss.
PIM stands for Passive Intermodulation — interference generated when strong RF signals mix at a non-linear passive component (a loose connector, a contaminated joint, a damaged jumper). The mix produces new frequencies that fall back into the receive band and quietly degrade throughput and uplink coverage. PIM is invisible to a standard sweep test, so it requires its own measurement.
HexTel runs PIM at close-out using carrier-spec test equipment and target dBc threshold. Failed tests trigger structured PIM hunting: connector re-torque, line swap, antenna-interface inspection, and distance-to-PIM localization. The site doesn't go back to acceptance until the reading sits at or below the threshold in the scope document.
PIM (Passive Intermodulation) is unwanted interference generated when two or more strong RF signals mix at a non-linear point in a passive component — a loose connector, a corroded joint, a damaged jumper, a rusted bolt near the antenna. The mixing creates new frequencies that fall back into the receive band, degrading throughput and uplink coverage.
PIM directly hurts site performance. A site with a -85 dBc PIM source can show 20–30% throughput loss, dropped calls, and reduced cell-edge coverage even when every other metric looks clean. Carriers test PIM at acceptance to catch it before the site goes live, and again whenever performance degrades unexpectedly.
Carrier acceptance thresholds vary by program and band, but -153 dBc and -155 dBc at +43 dBm test power are common pass/fail values for new builds. Some bands (especially low-band) require tighter thresholds; some legacy or retrofit work runs to -150 dBc. The RFDS or scope document specifies the exact target.
PIM hunting is the field troubleshooting workflow used to locate the source of a failed PIM test. The technician walks the line — re-torquing connectors, swapping jumpers, sweeping with a PIM tester at distance-to-PIM (DTP) mode — until the reading drops below threshold. A failed PIM hunt rarely has a single cause; it's a process-of-elimination.
In order of frequency: under-torqued or contaminated connectors, damaged hybrid/transmission line, antenna-to-jumper interface, RRU-to-line interface, and external sources nearby (rusted bolts on the tower, loose hardware on the platform, nearby antennas with PIM). Site age and weather exposure dominate the failure distribution.
Yes. PIM testing is part of standard new-build close-out across HexTel's coverage states. Tester models (Anritsu PIM Master, Kaelus iPA, etc.) and threshold targets are matched to the carrier's acceptance package, with reports archived against the site record.
A 30-minute scoping call covers your portfolio, carrier acceptance thresholds, and the cleanest path to clean test packets.
