Radiating Coaxial Cable Jacket Layout for Clamp Interference
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Solution Overview
Problem
Radiating coaxial cables experience performance degradation due to metal objects, such as fire-resistant clamps, which act as resonating elements increasing return loss and attenuation, necessitating secure installation methods that balance performance and safety.
Innovation Solution
A radiating coaxial cable design featuring a conductive shield with radiating and non-radiating longitudinal portions and a jacket with varying thickness, where the jacket portion facing the radiating shield is thicker, increasing the distance from external metal objects and reducing interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If metal clamps are used to securely fix the radiating coaxial cable, then the installation security and fire resistance are improved, but the return loss increases and cable performance deteriorates
Solution Approach 1:
A non-conductive intermediate layer (polymer jacket) is introduced between the metal clamp and the radiating shield to prevent direct electrical contact. This intermediary layer allows the metal clamp to provide mechanical support and fire resistance while blocking the harmful resonating effect on the radiofrequency signal.
Solution Approach 2:
The harmful function of the metal clamp (acting as a resonating element) is separated from its useful function (mechanical support). By extracting the direct contact between metal and radiating shield, the harmful electromagnetic resonance is eliminated while preserving the mechanical securing function through the non-conductive jacket layer.
2Object-affected harmful factors
If plastic clamps are used instead of metal clamps, then the return loss is reduced and cable performance is maintained, but the fire resistance and installation security are compromised
Solution Approach 1:
The beneficial properties of both plastic and metal clamps are merged into a single composite solution: the polymer jacket provides fire resistance and electrical insulation, while the metal clamp provides mechanical strength. Together they achieve both low return loss and high fire resistance.
Solution Approach 2:
The cable assembly becomes a composite structure with the polymer jacket serving as both protective layer and electrical insulator. This composite approach combines the fire resistance of thermally stable polymers with the mechanical strength of metal clamps while maintaining electromagnetic performance.
3Object-affected harmful factors
If the jacket thickness is increased to reduce interference from external metal objects, then the return loss is reduced, but the cable diameter and installation complexity increase
Solution Approach 1:
The jacket thickness is optimized locally rather than uniformly throughout. The polymer layer provides sufficient insulation where needed (at the radiating shield interface) while maintaining appropriate thickness elsewhere, achieving protection without excessive overall cable diameter.
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 thicker jacket portion effectively reduces return loss below the maximum threshold, allowing for reduced installation spacing of metal clamps, easier installation, lower costs, and improved safety in fire events.
Implementation Method 1
A metal object placed near a radiating coaxial cable on a radiating side thereof may affect its performance in terms of return loss and attenuation. A metal object near the cable on its radiating side indeed acts as a resonating element which reflects the radiofrequency signal
Data Source
AI summary
Disclosed is a radiating coaxial cable comprising an inner conductor, an insulating layer surrounding the inner conductor, a conductive shield surrounding the insulating layer and a jacket surrounding the shield. The conductive shield comprises a radiating longitudinal shield portion with radiating apertures and a non-radiating longitudinal shield portion with no radiating apertures. The jacket comprises a first jacket portion facing the radiating shield portion and a second jacket portion facing the non-radiating shield portion. The first jacket portion is thicker than the second jacket portion. This way, the cable is more protected against detrimental effects of metal objects brought near to or in contact with its radiating side.