Rooftop Passive Intermodulation (PIM) Problems?
Contact the experts at NRP for Passive Intermodulation (PIM) problems arising from rooftop coverings and related structures.
Detect and assess rooftop PIM sources
Precisely map PIM sources
Temporarily cover PIM sources to observe the level of benefit that can be achieved
Prepare comprehensive report
NRP’s PIM Mitigation Specialists will recommend and install the ideal interference reducing solution.
Improve performance by reducing external PIM at cell sites.
NRP understands the prevalence of passive intermodulation (PIM) in cellular systems related to rooftop coverings and roof-mounted structures. Solve your PIM issues. Reducing the interference will increase the reliability, capacity and data rate of cellular systems. NRP neutralizes sources of external PIM including:
- Roofing materials / construction
- Metal objects in front of antennas
- Metal strut fasteners
- Angle adapters
- Galvanic corrosion
- Metal snap-in hangers
- Hose clamps
We are your PIM Mitigation Specialists. Request a PIM Survey.
In partnership with ConcealFab, NRP offers a variety of solutions to help mobile operators identify and mitigate sources of external passive intermodulation (PIM) at cell sites.
What is PIM?
PIM stands for passive intermodulation. PIM appears as new frequencies created by the mixing of two or more signals in a passive, non-linear device such as a loose RF connector or rusty bolt. When these unwanted signals fall inside an operator’s uplink band, they raise the system noise floor which causes reduced coverage and increased dropped call rates.
Why is PIM a problem?
PIM is a well-known problem in cellular systems. Downlink signals at the cell site mix at passive, non-linear junctions in the RF path, creating new signals. If these new signals (intermodulation products) fall in an operator’s uplink band, they can elevate the noise floor and degrade system performance. RF equipment manufacturers have spent decades developing methods to improve the PIM performance of the RF components in antenna feed systems. Unfortunately, a low PIM feed system by itself does not guarantee that a site will perform to expectations. PIM sources beyond the antenna are now often the limiting factor for site PIM performance.
The highest risk for PIM occurs in close proximity to the many antennas on a cell tower; in front, above, below, and even behind them. The zone is defined as:
What does the PIM test process look like?
- 5 feet behind an antenna
- 10 feet directly above or below an antenna
- 100 feet in front of an antenna
The beginning PIM levels are measured and Distance-to-PIM (DTP) is estimated using a portable PIM analyzer.
All external PIM sources are precisely located using a PIM Probe attached to a spectrum analyzer tuned to the IM3 frequency.
PIM sources are temporarily covered with PIM blankets to observe the level of benefit that can be achieved.
PIM Shield™ products are permanently installed at the locations identified to suppress PIM and improve site performance.