Radiating Coaxial Cable With High-Silica Spacer for Fire Survivability
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Solution Overview
Problem
Existing radiating cables fail to maintain fire survivability with minimal signal loss at high temperatures, as required by building fire codes for communication systems in confined spaces.
Innovation Solution
A fire-resistant coaxial cable design featuring a high-silica fiberglass yarn wrapped around the center conductor, acting as a spacer and dielectric, maintains dielectric spacing and centricity under extreme heat, with a composition enriched with aluminum oxide and other oxides, and an outer conductor with apertures to allow RF signal transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional radiating cable is used, then RF signal transmission is enabled, but the cable fails to maintain operation at high temperatures during fires
Solution Approach 1:
The patent employs a composite dielectric structure combining high-silica fiberglass yarn (96-98% SiO2) with air gaps, creating a material system that maintains structural integrity at temperatures up to 1010°C. The fiberglass yarn's high silica content provides exceptional thermal stability, while the air component enhances heat resistance and reduces thermal conduction, enabling the cable to survive fire conditions while maintaining RF signal transmission.
2Reliability
If high silica fiberglass yarn is used as dielectric, then fire resistance is improved, but dielectric spacing must be precisely maintained under heat
Solution Approach 1:
The patent specifies precise compositional parameters for the fiberglass yarn (96-98% SiO2, with controlled amounts of Al2O3, Na2O, MgO, CaO, and Fe2O3) to optimize thermal stability and dimensional consistency. The yarn's high silica content and controlled oxide composition ensure minimal thermal expansion and consistent dielectric spacing even at 1010°C, reducing manufacturing tolerance requirements while maintaining fire resistance.
3Stability of the object's composition
If fiberglass yarn acts as continuous spacer, then center conductor centricity is maintained, but cable structure complexity increases
Solution Approach 1:
The high-silica fiberglass yarn serves multiple functions simultaneously: it acts as a dielectric material for RF signal transmission, a thermal barrier for fire resistance, and a mechanical spacer to maintain center conductor centricity and structural integrity. This multi-functionality eliminates the need for separate components, simplifying the overall cable structure while achieving fire survivability and signal stability.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The cable sustains 1010°C temperatures for two hours while maintaining RF signal transmission, ensuring communication continuity during fires.
Implementation Method 1
The air, yarn threads, and air within the interstitial spaces between the threads serve as a dielectric between the center and outer conductors
Implementation Method 2
The yarn threads have a high, greater-than-95% silica content that is enriched with over 3% aluminum oxide (Al2O3)
Data Source
AI summary
A fire resistant radiating coaxial cable that employs a high-silica fiberglass yarn spacer is described. The yarn material has mass fraction of silica (SiO2) between 95.0% and 96.5%, a mass fraction of aluminum oxide (Al2O3) greater than 3%, and a mass fraction of calcium oxide (CaO) less than 0.5%. The yarn can be wound in a low-helix-angle helix around the center conductor such that less than half fills the annular space between it and the outer conductor. The cable is configured to maintain a relatively coaxial relation between a center conductor and an outer conductor under intense fire conditions.