Low PIM Multiplexers

A Low PIM multiplexer is an RF filter network designed to combine or separate multiple frequency bands while minimizing passive intermodulation (PIM) distortion, which can degrade signal quality in high-performance wireless systems.

PIM occurs when nonlinearities in passive components (like connectors, cables, or filters) create intermodulation products—unwanted signals generated from two or more high-power RF signals mixing together. These interfere with system performance, especially in cellular and wireless networks.

Low PIM is critical in systems where multiple high-power carriers coexist (e.g., multi-band cellular base stations), because even small intermodulation signals can degrade receiver sensitivity, cause dropped calls, and interfere with adjacent channels.

Common causes of PIM in multiplexers include:

• Poor mechanical contacts (e.g., loose connectors or screws)

• Use of ferromagnetic materials (like nickel-plated surfaces)

• Contaminants (e.g., dirt, oxidation) on RF paths

• Improper soldering or assembly

PIM is usually measured using a two-tone test, applying two high-power signals (typically 20–43 dBm) and measuring the resulting intermodulation products, usually the 3rd-order PIM level, in dBc (decibels below carrier). Low PIM products are typically -150 dBc or better.

• Cellular base stations (2G/3G/4G/5G)

• DAS (Distributed Antenna Systems)

• Small cells and repeaters

• Satellite ground stations

• Public safety communication systems

Low PIM multiplexers are built with:

• Non-ferromagnetic materials (e.g., silver-plated, aluminum)

• Precision mechanical construction to reduce micro-arcing

• Careful assembly techniques to eliminate loose contacts

• High-quality connectors (like DIN or 4.3-10) rated for low PIM

Yes. Over time, corrosion, vibration, thermal cycling, or loose connections can degrade PIM performance. Regular maintenance and PIM testing are important in high-reliability RF systems.

Low PIM multiplexers are designed to balance low intermodulation, low insertion loss, and high isolation between bands. Achieving ultra-low PIM may slightly increase size or cost, but well-designed units maintain low loss (typically <0.5 dB per path) and high isolation (often >60 dB) without compromising RF performance.

Low PIM multiplexers are typically rated for high continuous RF power, often 100–300 W per port or more, depending on the band and design. Proper power handling is essential because high RF power increases the risk of PIM generation if materials or mechanical contacts are inadequate.

Most Low PIM multiplexers are band-specific, designed for fixed cellular or public safety frequency allocations. Custom or wideband designs are possible, but tighter frequency definitions generally allow better isolation, lower insertion loss, and improved PIM performance.

• Factory PIM testing verifies the multiplexer itself under controlled conditions before shipment.

• Field PIM testing evaluates the entire RF path (multiplexer, cables, connectors, antennas) after installation.

Even a low-PIM multiplexer can exhibit poor system PIM if installation practices are incorrect.

Typical PIM performance levels include:

• -150 dBc or better (for premium-grade equipment)

• Some systems require -153 dBc or lower, especially in 5G and carrier aggregation scenarios

• Use certified Low PIM components (multiplexers, cables, connectors)

• Ensure tight, clean, and corrosion-free connections

• Avoid ferromagnetic materials

• Perform regular PIM testing

• Use torque wrenches to meet manufacturer tightening specs

Key selection criteria include:

• Frequency bands and channel spacing

• Required PIM level (e.g., -150 dBc vs -153 dBc)

• Power handling capability

• Connector type (DIN, 4.3-10, N-type)

• Environmental rating (indoor, outdoor, temperature range)

• Compliance with carrier or regulatory requirements

To place an order for Low PIM multiplexers please contact us and we will help you!