Dielectric Filter Groove Structure for Compact High-Selectivity Coupling

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Solution Overview

Problem

Current dielectric filters face challenges in miniaturization without compromising performance, particularly in achieving high selectivity and transmission zeros, and their manufacturing is complex due to the need for additional structures like PCBs or plating patterns which can cause spurious issues.

Innovation Solution

A dielectric filter design incorporating dual mode and single mode resonant units with specific resonant holes and groove structures, along with coupling adjustment holes, to achieve miniaturization and improved performance while simplifying manufacturing.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Volume of moving object

If the filter size is reduced through miniaturization, then the volume and weight of the radio unit decrease, but the performance such as insertion loss and out of band attenuation deteriorates

Engineering Contradiction:
Improvefilter sizeVSAvoidinsertion loss and out of band attenuation performance
Core Design Contradiction:
Volume of moving objectVSReliability

Solution Approach 1:

The patent merges capacitive and inductive coupling structures into a single integrated groove structure formed in the dielectric body. This unified structure achieves both types of coupling simultaneously, enabling the filter to maintain high selectivity and transmission zeros while being miniaturized, thus resolving the contradiction between size reduction and performance maintenance

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The groove structure extends in multiple dimensions within the dielectric body, creating complex three-dimensional coupling paths. This multi-dimensional approach allows the filter to achieve high selectivity through both capacitive and inductive coupling effects without increasing the overall footprint, enabling miniaturization while maintaining performance

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

2Reliability

If additional structures such as PCB or plating pattern are used to implement capacitive coupling, then transmission zeros can be achieved, but the manufacturing complexity increases and spurious issues occur at the low side of pass band

Engineering Contradiction:
Improvetransmission zero formationVSAvoidmanufacturing complexity and spurious issues
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent extracts the coupling function from separate additional structures (PCB or plating patterns) and integrates it directly into the dielectric body through grooves. This eliminates the need for external coupling structures, simplifying manufacturing and removing the source of spurious issues while maintaining transmission zero formation capability

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The groove structure acts as an intermediary element within the dielectric body that provides both capacitive and inductive coupling pathways. This internal mediator structure replaces external PCB or plating solutions, achieving the same electrical function with simpler manufacturing and without introducing spurious signals

Inventive Principle:
Principle #24Intermediary (Mediator)

3Reliability

If cut corner or tuning hole is used on chamber surface to implement main coupling of dual mode resonator, then coupling can be achieved, but the manufacturing difficulty increases

Engineering Contradiction:
Improvemain coupling implementationVSAvoidmanufacturing difficulty
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The patent combines multiple coupling functions (main coupling and cross coupling, capacitive and inductive) into a single groove structure. This unified approach simplifies manufacturing by requiring only one type of feature to be formed in the dielectric body, rather than multiple different features like cut corners and tuning holes

Inventive Principle:
Principle #5Merging (Combining)

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

The design minimizes filter size and weight, enhances production efficiency, and improves radio performance while maintaining high selectivity and reducing spurious issues.

Implementation Method 1

Each of the resonators generates a resonant frequency at an operating pass band

Methodology Applied
Scientific EffectResonance: Resonance

Implementation Method 2

a body; at least one dual mode resonant unit arranged in the body

Methodology Applied
Scientific EffectDielectric: Dielectric

Data Source

PatentEP4252311B1Dielectric filter
Publication Date: 2026.01.21 TELEFONAKTIEBOLAGET LM ERICSSON (PUBL)
  • EP4252311B1 patent drawingFigure 1
  • EP4252311B1 patent drawingFigure 2~3
  • EP4252311B1 patent drawingFigure 4A~4B

AI summary

Disclosed is a dielectric filter. The dielectric filter includes a body; at least one dual mode resonant unit and at least one single mode resonant unit arranged in the body; and a groove structure formed in the body and configured to partially separate the at least one single mode resonant unit and the at least one dual mode resonant unit adjacent thereto. Each dual mode resonant unit at least has a first frequency resonant hole and a second frequency resonant hole. Each single mode resonant unit has a third frequency resonant hole. The first frequency resonant hole has a first longitudinal extension line perpendicular to a second longitudinal extension line of the second frequency resonant hole. The third frequency resonant hole has a third longitudinal extension line parallel to the first longitudinal extension line.