Triaxial Cable Inner Shield Resistance Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Triaxial cables in combined DC/AC measurement systems face challenges in controlling resonance effects during AC measurements, particularly due to parasitic coupling and standing waves on the inner shield conductor, which can disrupt the characteristic impedance and lead to measurement inaccuracies.
Innovation Solution
A triaxial cable design featuring an inner shield conductor with adjustable resistance, which is coaxial with the center conductor and outer shield conductor, is used to control resonance by dissipating resonance effects, achieved through the use of a lossy dielectric layer or metallic poor conductors like steel, allowing for specific resistance values such as 1 ohm per foot.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the inner shield conductor has low resistance, then electrostatic leakage is effectively guarded during DC measurements, but resonance effects and standing waves increase during AC measurements
Solution Approach 1:
The inner shield conductor's resistance is changed from low (for DC guarding) to a specifically optimized higher value (0.1-100 ohms per foot) to control resonance during AC measurements. This parameter change allows the same conductor to serve dual functions by adjusting its electrical properties to match measurement requirements.
Solution Approach 2:
The inner shield conductor is given non-uniform local properties through the use of lossy dielectric material with specific resistivity (0.01-10 ohm-centimeters) that varies along the conductor. This creates localized damping zones that suppress resonance effects at critical points while maintaining overall shielding effectiveness.
2Object-affected harmful factors
If the inner shield conductor has high resistance, then resonance effects are reduced during AC measurements, but electrostatic leakage protection decreases during DC measurements
Solution Approach 1:
Instead of using uniformly high resistance, the patent optimizes the resistance parameter to a specific range (0.1-100 ohms per foot) that provides sufficient resonance damping while maintaining adequate electrostatic guarding capability. This optimized parameter range resolves the contradiction by finding the optimal balance point.
Solution Approach 2:
The inner shield conductor is constructed as a composite structure combining metallic poor conductor materials (like steel) with lossy dielectric layers. This composite provides both the necessary resistance for resonance control and sufficient conducting properties for electrostatic guarding during DC measurements.
3Object-affected harmful factors
If a lossy dielectric layer is used in the inner shield conductor, then resonance is dissipated effectively, but manufacturing complexity increases
Solution Approach 1:
The lossy dielectric layer serves multiple functions simultaneously: it provides resistance for resonance damping, maintains insulation properties, and structurally supports the inner shield conductor. This multi-functionality reduces the need for additional components, simplifying manufacturing despite the specialized material requirement.
Solution Approach 2:
The lossy dielectric layer can be implemented as a porous or fibrous material that is easier to manufacture and integrate than solid homogeneous materials. These porous structures provide high surface area for resistance while maintaining flexibility and ease of assembly in the cable construction process.
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
This design effectively guards against electrostatic leakage during DC measurements and minimizes resonance disturbances during AC measurements, ensuring accurate parameter measurement by dissipating resonance on the inner shield conductor, thereby maintaining measurement integrity.
Implementation Method 1
The inner shield conductor 16 has a resistance (ohms/foot) chosen to control resonance on the inner shield conductor 16
Data Source
AI summary
A triaxial cable having a center conductor; an outer shield conductor coaxial with the center conductor; and an inner shield conductor coaxial with the center conductor and located between the center conductor and the outer shield conductor. The inner shield conductor has a resistance adapted to control resonance on the inner shield.