Coaxial Cable Air Layer and Straight Crest Design
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Solution Overview
Problem
Coaxial cables with corrugated outer conductors face challenges in signal propagation velocity due to varying relative dielectric constants along the cable length and difficulty in bending and cutting, primarily because of the uneven shape of the insulator and the corrugation crests and troughs, leading to inconsistent signal propagation and cumbersome cutting processes.
Innovation Solution
Incorporating an air layer between the insulator and the corrugation crest of the outer conductor, with a specific diameter relationship and a straight line section in the corrugation crest, to maintain a constant relative dielectric constant and facilitate easy cutting, by forming a corrugated tube shape with corrugation crests and troughs and using materials like copper for the conductors and high-density polyethylene for the insulator.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the outer conductor is made corrugated to improve flexibility, then the bending process becomes easier, but the relative dielectric constant varies along the cable length causing inconsistent signal propagation
Solution Approach 1:
The patent applies local quality by creating a straight line section in the corrugation crest at specific locations along the cable. This localized modification ensures that at these particular positions, the dielectric constant remains constant, providing stable signal propagation reference points while the rest of the corrugated structure maintains flexibility. The straight line section is positioned at a height corresponding to a specific ratio (0.3-0.7) of the corrugation depth, creating localized zones of improved electrical characteristic stability.
2Ease of manufacture
If the corrugation crests have a square wave shape to simplify manufacturing, then the structure is easier to produce, but the cable cutting becomes difficult and results in oblique cuts
Solution Approach 1:
The patent applies preliminary action by pre-forming straight line sections in the corrugation crests during the manufacturing process. These straight line sections are created in advance at specific positions along the cable length, providing predetermined cutting planes that will facilitate clean, perpendicular cuts when the cable is later cut. This preliminary structural preparation eliminates the difficulty of cutting corrugated cables while maintaining the square wave corrugation shape for ease of manufacturing.
3Speed
If the insulator diameter is increased to reduce the relative dielectric constant, then the signal propagation velocity increases, but the cable diameter increases reducing flexibility
Solution Approach 1:
The patent applies parameter changes by modifying the geometric parameters of the corrugation structure rather than simply increasing the insulator diameter. By creating straight line sections in the corrugation crests and optimizing the corrugation geometry (depth, pitch, and shape), the patent achieves effective reduction of the relative dielectric constant while maintaining a compact overall cable diameter. This allows improved signal propagation velocity without sacrificing cable flexibility.
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 reduces the relative dielectric constant, increases signal propagation velocity, and simplifies the cutting process by maintaining a consistent cross-sectional shape, enhancing the cable's flexibility and manufacturing ease while improving signal transmission efficiency.
Implementation Method 1
a signal propagation velocity of the coaxial cable and a relative dielectric constant of the cable have a relationship described in the expression (1) above. Here, the relative dielectric constant of the cable is minimized so as to increase the signal propagation velocity.
Data Source
AI summary
A coaxial cable including: an inner conductor located at the center portion of the cable; an insulator surrounding the outside of the inner conductor; an outer conductor surrounding the outside of the insulator; and a sheath surrounding the outer conductor, wherein the outer conductor is provided to have a corrugated tube shape having corrugation crests and corrugation troughs formed therein, and wherein an outer diameter “I” of the insulator, an inner diameter D1 of the corrugation crest formed in the outer conductor, and an inner diameter D2 of the corrugation trough formed in the outer conductor have the following relationship:D1+D22≥I≥D2,and an air layer is formed between the insulator and the corrugation crest of the outer conductor, and a straight line section is provided in the corrugation crest of the outer conductor.