Article: What Is PIM And Why Is It Crucial For Antennas?
PIM, also known as ‘Passive Intermodulation’ represents the intermodulation products generated when two or more signals transit through a passive device with nonlinear properties. PIM can be caused by amplitude modulation, damaged RF equipment, metal interference or unclean, loose connectors, cables or poor-quality antennas. In modern times, managing wireless network infrastructure and antenna products have become a complex process as different technologies are typically integrated in base stations. Moreover, with the launch of enhanced Mobile Broadband (eMBB), Ultra-Reliable Low-Latency Communications (URLLC), and Massive Machine Type Communications (MMTC), it has become increasingly important to detect and mitigate PIM, as LTE and 5G networks are particularly sensitive to it. Besides mobile operator networks, low-PIM antennas are in great demand for private networks with applications in enterprise networking, critical communications and industrial IoT.
What to consider while buying antennas
In the planning and deployment stages of large-scale communication projects, care must be taken to invest only in the highest quality, low-PIM certified products. If PIM interference overlaps with a network’s base receive frequencies, it can cripple network throughput and performance. As per industry standard, PIM levels of -100 dBm or lower are considered as good, and the lower the number – the better the product, especially if you are considering antennas for public safety applications and trunking systems. Sinclair’s signature Aurora Series antennas like the SC366 family feature Industry-leading -150 dBc PIM rating, one of the best in the world.
Conducting true PIM tests
Many organizations test individual components of the antennas for PIM during the design and manufacturing stage to ensure they are not sources of interference once assembled. A true PIM test can be completed considering the right environment, proper connectors, clamps and high-quality PIM-certified equipment. Sinclair manufactures a vast line of PIM-certified products like antennas, clamps etc., truly providing a 360-degree solution to address the needs of customers with strict, low-PIM requirements. Additionally, Sinclair’s engineering and production team are globally reputed for their ability to test and manufacture custom low-PIM antennas unique to customer applications, even with the most stringent of specifications.
Product quality and PIM
Besides external sources like extreme weather, storms, or lightening – likely PIM causes include poor quality antenna components, water infiltration into transmission equipment, rusting etc. To avoid the phenomenon known as ‘the rusty bolt effect’, check antennas to ensure they are heavy-duty and weather-proof. Sinclair’s Aurora collinear omni antennas are light-weight with a PIM-certified, UV-protected fiberglass radome, with high wind rating for long life, and are DC grounded for lightning protection (designed according to IEC62305 part 1-4 and VDE0855-300, fulfilling the requirements of lightning protection class II). They work perfectly in temperature ranges of even -40°F to +140 °F (i.e. -40°C to +60°C), with outstanding bandwidth and highly stable RF performance across the whole band!
Supporting equipment PIM checks
Check Cable Faults: Ensure that cables are PIM-certified and tested for faults.
Avoid Braided RF cables: High PIM is noticed when there is a use of braided RF cables. This is because the miniscule holes in the braid design which may be part of the braid shield or foil wraps act like loose connections during tests.
Regular Maintenance: Appropriate upkeep and maintenance of equipment is vital to keeping PIM low. Cleaning and Inspection is the foundation of great performance. Suitable torque is also important, as this helps the center connector avoid damage.
PIM-certified and tested products from reliable sources are becoming increasingly critical as cellular systems age and carrier count increases. PIM tests that were not considered important a few years ago when cellular and public safety systems were loaded lightly is suddenly becoming a vital part of current maintenance. Next-generation networks need higher transmission fidelity, and operators today face the challenge of maintaining B2B and B2C customer loyalty in a competitive arena. Hence, network PIM performance and product PIM testing are now imperative. Ultimately, a base station constructed with PIM-certified active and passive components in mind will cost much less to maintain in the long run and function much better. Contact Sinclair now to learn about our PIM certified series of products.