Page 49 - Power & Data Connectivity Expand Electronic Capabilities eBook
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size and weight are also key goals. Cable assemblies must be designed to perform reliably while assuming the smallest footprint possible. Furthermore, with so many components in such a small space, maintenance can be very challenging. If an interconnect fails, it can be hard to troubleshoot the exact failure point.
The majority of 5G small cell applications are installed outdoors — around lamp poles, rooftops, and telephone poles — and may be 30-40 feet or more above the ground. As a result, 5G antennas require a lot of RF cable feeds, RF jumpers, jumper cables, and feeder cables, which can visually create a rat’s nest if not installed properly. All these cables must be designed to withstand the weather and other elements.
Moreover, installation can be a time-consuming, labor-intensive, and logistical nightmare, creating the potential for cables to be the weakest link in the system. There are numerous variables to consider. Is it the right cable or the right port? Is that connector properly terminated to that cable? Is the coupling properly torqued down? Is the whole assembly properly weather sealed? Are those cables properly captivated? Are the cables properly secured to the structure? Do they have the proper UV resistance?
Passive intermodulation
Passive intermodulation, or PIM, is a type of distortion that may occur in passive, non-linear components such as RF cables and connectors. In dense 5G systems, heavy customer usage can generate competing signals. When two or more signals mix, they can produce an additional undesired frequency. Cables and connectors play a large role in PIM, which may occur because of something resistive in the interconnect, the junctions between different types of passive components such as the connector and cable, ferrous materials, inadequate tolerance, or poor torquing.
While PIM is an issue for almost every wireless system, it is more noticeable in cellular applications such as 5G because the frequency bands used are very close to each other. PIM can create interference that limits receiving sensitivity, lowering the reliability, data rate, and capacity of the cellular system. This has the potential to result in decreased system capacity and data rates, as well as dropped calls. To prevent this, carriers often require low-PIM coaxial cables to ensure the cable and connectors are performing properly and are free of interference.
The solution: bundled coaxial cable and cluster connectors The cable
A bundled cable design can help create the perfect flexible antenna jumper for applications requiring multiple runs, such as on 5G small cells located on towers or building-top sites. A spiral configuration of multiple flexible and ultra- flexible, low-PIM, plenum-rated jumper cables can be created under a common polyurethane outer jacket to promote ease of installation and improved operation. The individual coaxial cable runs are spun together in such a way that the combination easily flexes, essentially creating a bundle, which is then run through a large jacket extruder where a rip cord is placed. This enables four or five individual cables to be fed into the back of a cluster connector. By using this method and creating a round cable bundle, a seal is also formed to provide extra protection, as the inner cables are protected by the outer jacket.

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