Antenna Indirect Interconnection for PIM Reduction

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Solution Overview

Problem

Existing multi-radiator antennas face challenges in assembly complexity and passive intermodulation (PIM) due to mechanical/galvanic connections between radiating elements and coaxial lines, which are difficult to manufacture and maintain in limited spaces.

Innovation Solution

The antenna arrangement employs indirect interconnections, such as capacitive or inductive couplings, between radiating elements and coaxial lines, eliminating direct physical contact and using snap-on mechanisms and insulating layers to facilitate easy assembly and reduce PIM.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If direct mechanical/galvanic connections are used between radiating elements and coaxial lines, then reliable electrical connections are achieved, but assembly complexity increases and passive intermodulation (PIM) is introduced

Engineering Contradiction:
Improveelectrical connection reliabilityVSAvoidassembly complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent introduces an intermediary coupling structure that enables indirect electrical connection between the radiating element and coaxial line without direct mechanical contact. This intermediary mechanism transmits electrical signals while avoiding the complexity and PIM issues of traditional screw joints, thus maintaining connection reliability while simplifying assembly

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent replaces the mechanical screw joint system with an indirect coupling system that does not rely on mechanical fastening. This substitution eliminates the need for threaded connections and tight space assembly, reducing assembly complexity while maintaining electrical connection reliability through non-mechanical means

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Strength

If screw joints are used to connect radiating elements and coaxial lines, then firm connections are achieved, but assembly time increases and PIM is generated

Engineering Contradiction:
Improveconnection firmnessVSAvoidassembly time
Core Design Contradiction:
StrengthVSLoss of time

Solution Approach 1:

The patent implements preliminary action by pre-configuring the coupling structures on both the radiating element and coaxial line to enable direct engagement without requiring threaded assembly. The connection geometry is prepared in advance to allow snap-fit or slide-in assembly, dramatically reducing assembly time while maintaining connection firmness through precise mechanical interlocking

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

Instead of using a screw to create firmness, the patent inverts the approach by using a friction-fit or snap-fit mechanism where the connection firmness is achieved through surface area contact and elastic deformation rather than threaded engagement. This inversion eliminates the time-consuming screw assembly while maintaining or even improving connection strength

Inventive Principle:
Principle #13The other way round (Inversion)

3Volume of moving object

If small dimension screw joints are used in limited space, then connections are achieved, but manufacturing difficulty increases and PIM is introduced

Engineering Contradiction:
Improveconnection spaceVSAvoidmanufacturing ease
Core Design Contradiction:
Volume of moving objectVSEase of manufacture

Solution Approach 1:

The patent extracts the screw joint from the limited connection space and replaces it with a simplified coupling structure that can be manufactured as an integrated part of the radiating element or coaxial line. This extraction eliminates the need for separate small screws and complex fastening features, making manufacturing easier while maintaining compact dimensions and avoiding PIM from metallic thread contacts

Inventive Principle:
Principle #2Taking out (Extraction)

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 approach simplifies the assembly process, reduces PIM, and maintains high performance by ensuring reliable electrical connections without the drawbacks of mechanical/galvanic contacts.

Implementation Method 1

indirect interconnections, such as capacitive or inductive couplings, between radiating elements and coaxial lines

Methodology Applied
Scientific EffectCapacitive coupling: Capacitance

Implementation Method 2

indirect interconnections, such as capacitive or inductive couplings, between radiating elements and coaxial lines

Methodology Applied
Scientific EffectInductive coupling: Electromagnetic Induction

Data Source

PatentEP3350872B1Antenna arrangement using indirect interconnection
Publication Date: 2021.07.07 CELLMAX TECH AB
  • EP3350872B1 patent drawingFigure 1
  • EP3350872B1 patent drawingFigure 2~3
  • EP3350872B1 patent drawingFigure 4~5

AI summary

An antenna arrangement comprising an antenna feeding network, an electrically conductive reflector and at least one radiating element arranged on said reflector is provided. The antenna feeding network comprises at least one substantially air filled coaxial line, each coaxial line comprising a central inner conductor and an elongated outer conductor at least partly surrounding the central inner conductor, wherein at least one radiating element and at least one coaxial line are configured to interconnect indirectly.