Coaxial Cable Shield Structure for Suck-Out Suppression

Solution Overview

Problem

Conventional coaxial cables experience a phenomenon called suck-out, which leads to rapid attenuation in specific frequency ranges, affecting signal transmission.

Innovation Solution

The coaxial cable design includes a central conductor with twisted conductor element wires, a first shield layer of longitudinally lapped metal wires, and a second shield layer of metal tape, with a twist pitch of the conductor element wires set between 6 and 10 times the outer diameter of the central conductor.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a conventional shield layer structure is used, then the cable structure is simple, but suck-out occurs causing rapid attenuation in predetermined frequency ranges

Engineering Contradiction:

Improvesignal transmission qualityVSAvoidshield layer structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The shield layer is divided into two separate layers: a first shield layer with longitudinally lapped metal wires and a second shield layer with a metal tape. This segmentation allows each layer to perform its specific function independently, preventing suck-out while maintaining structural integrity and signal transmission quality.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The shield layer combines two different shielding structures (longitudinally lapped metal wires and metal tape) to create a composite shield system. This composite structure effectively prevents suck-out phenomenon across a broader frequency range while maintaining cable flexibility and electrical performance.

Inventive Principle:

Principle #40Composite materials

2Reliability

If the twist pitch of conductor element wires is not controlled, then the manufacturing process is simple, but suck-out occurs causing rapid attenuation

Engineering Contradiction:

Improvesignal transmission qualityVSAvoidtwist pitch control

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The patent specifies a precise parameter range for the twist pitch of conductor element wires (6 times or more and 10 times or less the outer diameter of the central conductor). By controlling this geometric parameter within the specified range, the invention prevents suck-out phenomenon while maintaining manufacturability through clear design guidelines.

Inventive Principle:

Principle #35Parameter changes

3Object-affected harmful factors

If a single shield layer is used, then the device complexity is low, but it cannot effectively prevent suck-out and signal leakage

Engineering Contradiction:

Improvesignal leakage and radio wave intrusionVSAvoidshield layer configuration

Core Design Contradiction:

Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The shield layer is divided into two separate layers: a first shield layer with longitudinally lapped metal wires and a second shield layer with a metal tape. This segmentation allows each layer to perform its specific function independently, preventing suck-out while maintaining structural integrity and signal transmission quality.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The shield layer combines two different shielding structures (longitudinally lapped metal wires and metal tape) to create a composite shield system. This composite structure effectively prevents suck-out phenomenon across a broader frequency range while maintaining cable flexibility and electrical performance.

Inventive Principle:

Principle #40Composite materials

Data Source

PatentUS20250125545A1Coaxial cable and multi-core cable

Publication Date: 2025.04.17 SUMITOMO ELECTRIC INDUSTRIES LTD

AI summary

A coaxial cable includes a central conductor including a plurality of twisted conductor element wires, an insulator disposed outside the central conductor, a shield layer disposed outside the insulator, and a jacket disposed outside the shield layer. The shield layer includes a first shield layer and a second shield layer in an order from a position closest to the central conductor. The first shield layer includes a plurality of longitudinally lapped metal wires, and the second shield layer includes a metal tape disposed outside the first shield layer. An outer diameter of the central conductor is 0.2 mm or more and 0.4 mm or less, and a twist pitch of the conductor element wires of the central conductor is 6 times or more and 10 times or less the outer diameter of the central conductor.