Rail Transit Drives Upgrade of Multi-Band POI Combiner Components

New construction and expansion projects of domestic rail transit keep advancing in 2026.

Demand for shared multi-operator network coverage in confined subway and high-speed rail tunnels triggers mass replacement and upgrading of multi-system POI combiners and filter-combiner assemblies. 

Signal reflection on metal tunnel walls causes severe mutual interference among multi-band signals. 

Traditional discrete narrowband combiners fail to support simultaneous transmission of multi-spectrum signals for 2G/4G/5G networks of multiple operators, becoming a key bottleneck for network optimization and reconstruction.

Integrated full-band POI combiner solutions are widely adopted in current rail communication projects. 

Each unit integrates multiple band-pass and band-stop filter channels to realize combined transmission of full-standard signals across low and high frequency ranges. 

Core performance indicators include low passive intermodulation, high port isolation, wide-temperature stability and low insertion loss. These features suppress stray signal interference inside tunnels, cut the number of signal source equipment and reduce long-term operation power consumption.

Three major technical upgrading trends emerge in the industry:

First, lightweight optimization of cavity structures. New low-loss dielectric ceramics are applied to shrink component size without sacrificing power handling capacity, fitting narrow equipment cabins inside tunnels.

Second, integrated design of multi-channel filters and combiners. Independent filters are merged with combiner cavities to eliminate extra loss and intermodulation deterioration caused by excessive cable joints.

Third, wideband universal product development, covering full communication frequency range from 700MHz to 6GHz. A single component matches differentiated spectrum plans of rail operators in various cities and shortens customized R&D cycles.

Apart from domestic rail transit market, overseas cities launch 5G coverage renovation for subways and intercity railways, bringing steady growth in export orders of multi-band high-isolation combiners. 

Special performance requirements for RF passive components in long confined spaces continuously raise industrial technical barriers. Manufacturers with mature integrated filter-combiner solutions will maintain steady market competitiveness.