Sheet-Metal Dielectric Filter Unit for High-Q Wideband RF Suppression

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Solution Overview

Problem

Traditional ceramic waveguide (CWG) filters for 5G communication face limitations such as low Q-value, size constraints, poor out-of-band frequency attenuation, and reliability issues, making them unsuitable for wideband radio products and complex systems.

Innovation Solution

An integrated low-pass and band-pass filter unit formed by electroplated sheet metal with dielectric material coatings, featuring aligned resonators and adjustable coupling structures, which reduces size and weight while enhancing power handling capacity and reliability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If traditional metal cavity filters are used, then Q-value and power handling performance are improved, but size and weight increase

Engineering Contradiction:

ImproveQ-valueVSAvoidfilter weight

Core Design Contradiction:

ReliabilityVSWeight of moving object

Solution Approach 1:

The filter combines sheet metal structure with dielectric material coating to create a composite filter unit. The dielectric coating (with relative permittivity 2.2-10.0) enables higher Q-value performance while the sheet metal base maintains structural integrity and power handling capability, achieving a balance between performance and reduced weight compared to traditional all-metal cavity filters

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The invention changes the material parameters by applying dielectric coating with specific permittivity values (2.2-10.0) to the sheet metal resonators. This parameter change allows the filter to achieve higher Q-values without increasing size, as the dielectric material concentrates electromagnetic fields and enhances resonance characteristics

Inventive Principle:

Principle #35Parameter changes

2Weight of moving object

If ceramic waveguide filters are used, then size and weight are reduced, but Q-value and power handling capacity deteriorate

Engineering Contradiction:

Improvefilter weightVSAvoidQ-value

Core Design Contradiction:

Weight of moving objectVSReliability

Solution Approach 1:

The filter uses composite material construction where sheet metal provides structural strength and power handling capability, while dielectric coating enhances Q-value. This composite approach overcomes the limitations of pure ceramic waveguide filters which have lower power handling capacity despite their compact size

Inventive Principle:

Principle #40Composite materials

3Volume of stationary object

If ceramic waveguide filters are used, then size is reduced, but out-of-band frequency attenuation performance deteriorates

Engineering Contradiction:

Improvefilter sizeVSAvoidout-of-band frequency attenuation

Core Design Contradiction:

Volume of stationary objectVSObject-generated harmful factors

Solution Approach 1:

The invention merges low-pass filter and band-pass filter functions into a single integrated filter unit. The band-pass resonators provide frequency selection while the low-pass resonators provide harmonic suppression, achieving both compact size and excellent out-of-band attenuation performance in one integrated structure

Inventive Principle:

Principle #5Merging (Combining)

4Volume of stationary object

If ceramic waveguide filters are used, then size is reduced, but reliability in production and long-term operation deteriorates

Engineering Contradiction:

Improvefilter sizeVSAvoidproduction reliability

Core Design Contradiction:

Volume of stationary objectVSReliability

Solution Approach 1:

The invention uses sheet metal instead of fragile ceramic materials, making the filter more resistant to mechanical damage during production and operation. The sheet metal construction eliminates the risk of cracking that plagues ceramic waveguide filters, significantly improving production yield and long-term operational reliability

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

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 solution achieves smaller, lighter filters with improved Q-value, better power handling, and flexible design capabilities, enabling effective suppression of radio frequency signals across 8-18 GHz with reduced insertion loss.

Implementation Method 1

A part of each of the low-pass and band-pass resonators is coated with dielectric material

Methodology Applied

Scientific EffectDielectric: Dielectric

Implementation Method 2

one or more low-pass resonators and two or more band-pass resonators comprised in the inner cavity

Methodology Applied

Scientific EffectResonance: Resonance

Data Source

PatentUS12463313B2Integrated low-pass and band-pass filter unit formed by sheet metal coated with dielectric material

Publication Date: 2025.11.04 TELEFONAKTIEBOLAGET LM ERICSSON (PUBL)

AI summary

An integrated low-pass and band-pass filter unit comprises an inner cavity formed by a shell of conductive materials; one or more low-pass resonators and two or more band-pass resonators comprised in the inner cavity. The low-pass and band-pass resonators are integrally formed by electroplated sheet metal material, and a part of each of the low-pass and band-pass resonators is coated with dielectric material. The two or more band-pass resonators are arranged at two sides of the inner cavity such that at least two resonators are aligned to face each other. The integrated low-pass and band-pass filter unit further comprises a first separator of electroplated sheet metal arranged in the inner cavity between the low-pass resonators and band-pass resonators and a second separator of electroplated sheet metal arranged in the inner cavity between the band-pass resonators at the two sides of the inner cavity.