Antenna Feeding Network Coaxial Connector Attachment

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Solution Overview

Problem

Existing antenna feeding networks with air-filled coaxial lines face challenges in maintaining impedance and minimizing passive intermodulation (PIM) due to difficulties in achieving a consistent electrical connection between the coaxial connector and the antenna body, especially under mechanical forces from thick feeder cables.

Innovation Solution

The antenna feeding network incorporates a coaxial connector with an attachment portion directly attached to a longitudinally extending portion of the outer conductor, eliminating the need for a rigid bottom plate and using indirect connections and insulating layers to ensure electrical and mechanical stability, while also incorporating DC or RF grounding stubs for electromagnetic energy diversion.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If the coaxial connector body is attached to the bottom plate made of conductive material, then mechanical support is provided, but passive intermodulation (PIM) occurs due to inconsistent electrical connection

Engineering Contradiction:
Improvemechanical supportVSAvoidpassive intermodulation (PIM)
Core Design Contradiction:
StrengthVSObject-generated harmful factors

Solution Approach 1:

The patent introduces an electrically insulating bottom plate as an intermediary component between the connector body and the conductive antenna structure. This insulating bottom plate eliminates the harmful electrical connection path that causes PIM, while the connector body maintains mechanical attachment to support the assembly. The insulating material acts as a mediator that separates the electrical paths, preventing unwanted current flow between the connector body and antenna elements.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Object-generated harmful factors

If a separate coaxial cable is used to provide electrical connection, then PIM is reduced, but the arrangement occupies valuable space and increases cost

Engineering Contradiction:
Improvepassive intermodulation (PIM)VSAvoidnumber of parts
Core Design Contradiction:
Object-generated harmful factorsVSDevice complexity

Solution Approach 1:

The patent merges the electrical connection function with the existing connector and antenna structure by using the inner conductor of the coaxial line that is already present in the air-filled coaxial line arrangement. Instead of adding a separate coaxial cable as an additional component, the solution integrates the electrical connection path through the existing inner conductor, which is guided from the connector pin through the insulating bottom plate to the antenna elements, thereby eliminating the need for extra cables and reducing overall complexity.

Inventive Principle:
Principle #5Merging (Combining)

3Reliability

If soldering is used to attach the connector body to the bottom plate, then electrical connection is achieved, but PIM increases due to incorrect soldering of outer conductor

Engineering Contradiction:
Improveelectrical connectionVSAvoidpassive intermodulation (PIM)
Core Design Contradiction:
ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The electrically insulating bottom plate serves as a mediator that completely eliminates the need for soldering between the connector body and the antenna structure. By providing mechanical support without creating an electrical connection path, the insulating bottom plate removes the source of PIM that would otherwise be introduced by imperfect solder joints on the outer conductor or shield.

Inventive Principle:
Principle #24Intermediary (Mediator)

4Strength

If the attachment of coaxial connector to bottom plate is subjected to mechanical forces from thick coaxial feeder cables, then mechanical connection is strong, but consistent electrical connection becomes difficult to achieve

Engineering Contradiction:
Improvemechanical connectionVSAvoidelectrical connection
Core Design Contradiction:
StrengthVSReliability

Solution Approach 1:

The insulating bottom plate acts as a mediator that decouples the mechanical and electrical functions. It provides strong mechanical support to withstand forces from thick coaxial feeder cables while simultaneously preventing any electrical connection between the connector body and antenna elements. This separation ensures that mechanical strength does not compromise electrical connection quality, as the insulating material maintains consistent electrical isolation regardless of mechanical stress.

Inventive Principle:
Principle #24Intermediary (Mediator)

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 configuration provides a cost-effective, compact, and reliable electrical connection that maintains impedance and minimizes PIM, allowing for efficient signal transmission and reduced mechanical complexity, while also supporting DC communication and ancillary device functionality.

Implementation Method 1

incorporating DC or RF grounding stubs for electromagnetic energy diversion

Methodology Applied
Scientific EffectGrounding: Earthing

Implementation Method 2

grounding stubs for electromagnetic energy diversion

Methodology Applied
Scientific EffectResistive dissipation: Joule Heating

Data Source

PatentEP3411925B1Antenna feeding network comprising a coaxial connector
Publication Date: 2021.03.31 CELLMAX TECH AB
  • EP3411925B1 patent drawingFigure 1
  • EP3411925B1 patent drawingFigure 2~3
  • EP3411925B1 patent drawingFigure 4~5

AI summary

An antenna feeding network for a multi-radiator base station antenna and an antenna arrangement comprising such a feeding network is provided. The feeding network comprises substantially air filled coaxial lines and a coaxial connector for an antenna feeder cable, the connector being connected to at least one of the coaxial lines. The substantially air filled coaxial lines each have a central inner conductor and an elongated outer conductor surrounding the central inner conductor. The coaxial connector comprises a body having an attachment portion, the attachment portion being attached to, and arranged in abutment with, a portion of at least one outer conductor such that the body connects electrically and mechanically with the outer conductors of the coaxial lines.