Tactical Cable Using Bend-Insensitive Multimode Fiber
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Solution Overview
Problem
Conventional fiber optic cables lack durability and are prone to attenuation due to bending and strain in extreme environments like cellular towers, and they often require expensive transmitters for high bandwidth applications.
Innovation Solution
The development of a fiber optic cable with a polymer jacket and a tensile yarn strain relief element, using bend insensitive multimode fibers and a thermoplastic urethane extruded jacket, which allows for low attenuation and the use of inexpensive VCSEL transmitters, while maintaining a small cross-section for durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional fiber optic cables are used in extreme environments, then bandwidth capability is provided, but durability and resistance to bending/strain-induced losses deteriorate
Solution Approach 1:
The cable employs a composite structure combining a polymer jacket, aramid yarn tensile strength members, and bend-insensitive multimode optical fibers. This composite design provides both mechanical durability and optical performance, with the aramid yarn protecting against tensile forces and the polymer jacket providing environmental protection while maintaining flexibility.
Solution Approach 2:
The patent utilizes bend-insensitive multimode fibers with modified optical parameters that reduce sensitivity to bending and strain. These fibers maintain low attenuation characteristics even when subjected to environmental stresses, allowing reliable operation in extreme conditions without requiring expensive single-mode transmitters.
2Productivity
If large cable cross-sections are used to provide adequate data service, then bandwidth capability is improved, but wind loading and installation difficulty worsen
Solution Approach 1:
The cable uses bend-insensitive multimode fibers that maintain high bandwidth capability with a much smaller cross-section than conventional cables. This parameter change in fiber type allows achieving the same data service capacity with reduced physical dimensions, thereby minimizing wind loading on cellular towers.
Solution Approach 2:
The composite construction with high-strength aramid yarn tensile members allows the cable to achieve high bandwidth capacity in a compact form while maintaining the mechanical strength needed to resist environmental forces. The optimized composite structure provides maximum performance with minimum cross-sectional area.
Data Source
AI summary
Robust fiber optic cables and assemblies having low attenuation multimode optical fibers. The cables have low attenuation in tensile and mandrel wrap tests, and can have thermoplastic urethane jackets coextruded over tensile strength members that allow the cables to be pulled by the jackets. The cables have relatively small cross-sections yet have sufficient robustness to be deployed in extreme environments such as cellular tower applications.