Dielectric Filter Resonator With Offset Blind Holes for Negative Coupling

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Solution Overview

Problem

Current compact ceramic waveguide (CWG) filters struggle to maintain a small insertion loss while achieving a large out-band suppression, as they require more cascaded resonators for effective suppression, leading to increased loss and size.

Innovation Solution

A resonating structure with negative coupling holes, comprising a body made of solid dielectric material with two resonators connected by negative coupling holes, allows for adjustable negative coupling strength by varying the depth, shape, and position of these holes, enabling effective out-band suppression without increasing insertion loss.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If more cascaded resonators are used to achieve large out-band suppression, then out-band suppression is improved, but insertion loss increases and filter size increases

Engineering Contradiction:

Improveout-band suppressionVSAvoidinsertion loss

Core Design Contradiction:

Object-affected harmful factorsVSLoss of energy

Solution Approach 1:

The patent changes the coupling parameter from positive to negative coupling between resonators. This is achieved by introducing blind holes at specific positions between adjacent resonators, which transforms the coupling characteristics and enables the system to achieve both out-band suppression and low insertion loss with fewer resonators.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent introduces a new dimension of coupling control by adding blind holes that extend into the resonator bodies. This vertical dimension (depth of blind holes) provides an additional degree of freedom for adjusting coupling strength, enabling precise control of both positive and negative coupling to achieve optimal filter performance with reduced component count.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Object-affected harmful factors

If more cascaded resonators are used to achieve large out-band suppression, then out-band suppression is improved, but filter size increases

Engineering Contradiction:

Improveout-band suppressionVSAvoidfilter size

Core Design Contradiction:

Object-affected harmful factorsVSVolume of moving object

Solution Approach 1:

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent combines multiple functions into the blind hole structure: it serves as both a negative coupling mechanism and a tuning element. The blind holes are positioned to simultaneously achieve out-band suppression and control pass-band characteristics, reducing the need for additional separate components.

Inventive Principle:

Principle #5Merging (Combining)

3Object-affected harmful factors

If blind holes are deeply dug to achieve required negative coupling, then negative coupling is improved, but filter robustness deteriorates

Engineering Contradiction:

Improvenegative couplingVSAvoidfilter robustness

Core Design Contradiction:

Object-affected harmful factorsVSReliability

Solution Approach 1:

The patent employs asymmetric blind hole configurations where the first blind hole and second blind hole have different depths or positions. This asymmetric design allows precise control of negative coupling strength while maintaining adequate mechanical strength, avoiding the need for uniformly deep holes that would compromise robustness.

Inventive Principle:

Principle #4Asymmetry

Solution Approach 2:

The patent applies different blind hole depths and configurations at different locations between resonators. The blind holes are strategically positioned and sized to provide the required negative coupling only where needed, while other regions maintain full structural integrity, achieving a balance between electrical performance and mechanical robustness.

Inventive Principle:

Principle #3Local quality

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 allows for easy tuning of negative coupling between resonators, achieving low insertion loss and good out-band suppression performance with limited resonating structures, while maintaining filter robustness and ease of production.

Implementation Method 1

negative coupling (also known as 'capacitive coupling')

Methodology Applied

Scientific EffectCapacitive coupling: Capacitance

Implementation Method 2

dielectric filters that use materials with a high dielectric constant as transmission media

Methodology Applied

Scientific EffectDielectric resonance: Dielectric

Data Source

PatentUS12341230B2Resonating structure for a dielectric filter comprising a dielectric body including offset first and second blind coupling holes for adjusting the coupling strength there between

Publication Date: 2025.06.24 TELEFONAKTIEBOLAGET LM ERICSSON (PUBL)

AI summary

A resonating structure and a dielectric filter having the same are disclosed. The resonating structure comprises a body, at least one set of negative coupling holes, and a conductive material layer. The body is made of a solid dielectric material and comprises at least two resonators. The negative coupling holes are formed at a connection between two adjacent resonators. Each set of negative coupling holes comprises a first blind hole and a second blind hole disposed on two opposite surfaces of the body respectively. The first blind hole and the second blind hole are offset from each other in a plane perpendicular to a direction along which the first or second blind hole is dug. The conductive material layer covers surfaces of the body and surfaces of the first blind hole and the second blind hole.