PIM (Passive Intermodulation) is just as much a concern today as ever in the wireless marketplace. Operators know that PIM can have a devastating impact on high speed data performance, in particular, seriously reducing the site coverage area for high speed services. For example, a 9 dB increase in PIM can reduce the area of high speed coverage by over 60 percent.
CommScope is committed to helping operators manage and limit PIM interference in their networks. We launched a comprehensive PIM Happens—Just Not On Our Watch program two years ago, which bundles together all sorts of information and tools about PIM for network engineers. We recommend a five-prong approach for mitigating PIM based on awareness, prevention, identification, resolution, and support. If you would like to learn more about the entire PIM Happens program, use the link above.
I would like to highlight a free resource that works well as part of the prevention part of the program—the Band and Block PIM Calculator.
The Band and Block PIM Calculator allows designers to select various combinations of transmit (downlink) frequency bands/blocks to determine whether there are any theoretical possibilities of 2nd or 3rd order PIM in the companion receive (uplink) frequency bands. This calculator can help engineers during the design phase of their cell site projects as a first-line defense against PIM. It comes in North American and EMEA versions, incorporating the different frequency bands in those regions. The EMEA version should work okay for Asia Pacific, too. However, some CALA countries use a combination of US and European frequencies, and all those combinations make the display very difficult. We are exploring options for how we might modify the PIM calculator to better help our CALA customers.
Have you tried the Band and Block PIM Calculator yet? Do you have any feedback for potential improvements? Leave a comment if so. I have heard from a few of our North American customers that they find it useful to use during the design phase of a site build-out. As a reminder, I wrote previously about a tool CommScope offers for calculating RF Path return loss. I got some good feedback about the tool, so I just want to share that link again.
About the Author
Louis Meyer, P.E., is director of technical sales for CommScope Mobility Solutions. Lou has spent a lifetime advancing RF technology, taking it from the drawing board to practical use. Over the years in various roles with Allen Telecom, Andrew Ltd. and CommScope, Lou was responsible for supporting the sales teams for such solutions as remote antenna control systems, transmission lines, diplexers and other important components. Prior to joining Allen Telecom, Lou worked with Decibel Products as vice president of antenna design and vice president of international OEM relations. Earlier, Lou worked with Harris Corporation in RF communications and Bendix Corporation in their missile systems division. Lou holds five patents and has been active as a chair and vice-chair of the TIA’s TR-8.11 Antenna Standards subcommittee. He earned his bachelor of science degree in electrical engineering from Marquette University in Milwaukee, Wisconsin and is currently a registered professional engineer in the state of Texas.
2 comments for "Preventing PIM"
This link doesn't work for me, others are fine, could you please check?
"PIM Happens—Just Not On Our Watch"
Bill Walter says:
Hi Dragon - sorry about the link not working. We have updated it, so it should work now. Here's the URL, too: http://www.commscope.com/company/eng/support/programs/1221558_18361.html. Thanks for reading!