Dielectric Tuning Element for Intermodulation-Free High Frequency Filter

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Solution Overview

Problem

Conventional high-frequency coaxial filters face intermodulation problems due to metal wear at critical contact transitions, inadequate frequency stabilization against temperature changes, and manufacturing complexities, leading to costly and inefficient designs.

Innovation Solution

A high-frequency filter featuring a dielectric tuning element with an external thread and a socket connected to the housing cover, allowing for precise frequency adjustment without intermodulation issues, and enhanced temperature compensation through material thermal expansion mismatch, eliminating the need for additional sealing measures.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If a metal threaded tuning element is used for frequency adjustment, then frequency tuning capability is achieved, but metal wear at contact transitions causes intermodulation products and interfering frequencies

Engineering Contradiction:

Improvefrequency tuning capabilityVSAvoidintermodulation free operation

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The patent replaces the metal-threaded mechanical tuning system with a ceramic disc tuning element that is axially movable within a threaded socket. The ceramic material eliminates metal-to-metal contact, preventing wear and intermodulation products while maintaining frequency tuning capability through axial position adjustment.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The threaded socket acts as an intermediary mechanism that converts rotational motion into axial displacement of the ceramic tuning element. This indirect coupling allows precise frequency control without direct metal contact between the tuning element and housing, eliminating the source of intermodulation issues.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Ease of operation

If conventional metal tuning elements are used, then frequency adjustment is possible, but additional sealing measures are required increasing device complexity

Engineering Contradiction:

Improvefrequency adjustment capabilityVSAvoidsealing measures

Core Design Contradiction:

Ease of operationVSDevice complexity

Solution Approach 1:

The patent changes the material parameter of the tuning element from metal to ceramic, which has different thermal expansion characteristics. This parameter change eliminates the need for additional sealing measures because the ceramic material's thermal stability prevents the sealing issues that arise with metal components under temperature variations.

Inventive Principle:

Principle #35Parameter changes

3Ease of operation

If metal threaded components are used for tuning, then frequency control is achieved, but manufacturing precision requirements increase due to critical contact transitions

Engineering Contradiction:

Improvefrequency control capabilityVSAvoidcontact transition precision

Core Design Contradiction:

Ease of operationVSManufacturing precision

Solution Approach 1:

The patent extracts the tuning function from the threaded contact interface and relocates it to the axial position of the ceramic disc within the threaded socket. This separation removes the critical contact transition from the tuning mechanism, eliminating the need for high manufacturing precision at the contact interface while preserving frequency control capability.

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

The solution provides effective frequency tuning and improved temperature stability while preventing intermodulation and reducing manufacturing costs by using dielectric materials and a novel structural configuration.

Implementation Method 1

The high-frequency filter according to the invention comprises a resonator (1) having an internal conductor (10) and an external conductor housing (20, 22, 24), frequency tuning being provided by way of a tuning element (30), which consists of or comprises a dielectric material

Methodology Applied

Scientific EffectDielectric: Dielectric

Implementation Method 2

The housing base (20), the housing wall (24) and the internal conductor (10) conventionally consist of a metal, in other words of a first material, which has a first thermal expansion coefficient. The tuning element (30) consists of a third material, which has a third thermal expansion coefficient

Methodology Applied

Scientific EffectThermal expansion: Thermal Expansion

Data Source

PatentUS9748622B2Tunable high frequency filter

Publication Date: 2017.08.29 TELEFONAKTIEBOLAGET LM ERICSSON (PUBL)

AI summary

The invention relates to an improved tunable high frequency filter of coaxial construction, characterized, inter alia, by the following features: The high frequency filter comprises an outer conductor housing (24) having an inner conductor (10) and a housing cover (22); the resonator (1) comprises a tuning element (30) arranged opposite the inner conductor (10), which in the housing cover (22) is held position-adjustably in the axial position of the tuning element (30), at least indirectly, and which extends into the internal space of the resonator; the tuning element (30) comprises a dielectric material, or is formed from a dielectric material such that between the outer thread (32) and the inner thread (41), current transitions are avoided.