Low PIM is the buzzword of the week in wireless infrastructure as the industry decides on the new “standard” RF connector. PIM stands for Passive Intermodulation (which is similar but not the same as IMD – that is for active components) and is measured in dB’s. PIM is defined as the unwanted signal or signals generated by the non-linear mixing of 2 or more frequencies, but what does it really mean to the consumer? High PIM means poor cellular reception and limited bandwidth to the end user, which in turn means lost customers to the carrier. Low PIM means strong signals with more bandwidth for more users, which means happy customers and higher revenues for the carrier. From a hardware perspective, it means that each and every connection must be designed to minimize PIM and tested to ensure it is installed properly. That is where Amphenol is the expert.
“Amphenol has been testing and optimizing PIM in our connectors for almost two decades.”
The current standard wireless RF connector – 7/16 connectors – are large and heavy. They have been in the field for years, are proven to be reliable, and have good PIM performance. However, in the age of smartphones, increased data usage equates to increased RF connector density, and the 2”x 2” flange required to mount a 7/16 is too large.
The current alternative – N type connectors – are smaller and fit on a 1”x 1” flange, but cannot match the torque spec or PIM performance of the 7/16 connector.
The front runners for the crown are the 4.1/9.5 and the 4.3/10 connector. The 4.1/9.5 connector is an old interface and is commercially available, but has not achieved widespread adoption. For a list of available current generation Low PIM adapters follow the hyperlink. The 4.3/10 is a new interface based on a new specification, with nearly no time in the field. Let’s compare the two technically first, then understand the industry forces acting on the choice of next gen connectors:
- Both meet or exceed the performance of the 7/16, but fit on a 1” flange
- Both can handle higher torque loads than N type, reducing install failures
- 4.1/9.5 PIM performance varies when loose or under strain (similar to 7/16)
- 4.3/10 has the unique ability to have stable PIM while connector is loose or under strain – this increases reliability and allows it to be hand tightened
- 4.3/10 has separate mechanical and electrical planes for optimized PIM
4.1/9.5 Bulkhead Flange Adapter
- A major US carrier is pushing all large RF interfaces to 4.1/9.5
- European standard is likely to be 4.3/10
- Many carriers have not adopted 4.1/9.5, seemingly waiting for the 4.3/10
While Verizon is supporting 4.1/9.5 at the moment, the industry at large seems to be holding off as the 4.3/10 is a strong contender for the crown of “Standard Low PIM” connector. Very likely both standards will exist and create their own niche, as is seen with the current gen products. Amphenol continues to broaden its industry leading product portfolio, offering the 4.1/9.5 in multiple configurations, and developing the 4.3/10 product line. Please contact us to learn more.
Years of Experience
Amphenol has been testing and optimizing PIM in our connectors for almost two decades. We offer 100% PIM testing on critical products and can work with our customers to optimize PIM at the system level. To get really smart on PIM, read the white paper written by our very own RF guru, David Weinstein.