Composite Tuning Structure in Cavity Filters for High Q Linearity

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Solution Overview

Problem

Conventional cavity filters suffer from poor tuning capability and linearity, leading to excessive linear slope increase and degraded performance, particularly due to the continuous extension of tuning screw rods into resonant cavities.

Innovation Solution

A novel cavity filter design incorporating a tuning component with a high-conductivity and non-conductivity parts, allowing even electric field distribution and adjustable resonance, featuring a resonant column mounted on the cover plate side or bottom, with a central axis alignment and adjustable fastening.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If the tuning screw rod continuously extends into the resonant cavity, then the resonance frequency can be adjusted, but the linear slope of the cavity filter increases excessively fast, degrading filter performance

Engineering Contradiction:
Improvetuning capabilityVSAvoidlinearity
Core Design Contradiction:
Adaptability or versatilityVSReliability

Solution Approach 1:

The tuning component is divided into a high-conductivity part and a non-conductivity part. The high-conductivity part is disposed inside the resonant cavity to adjust resonance frequency, while the non-conductivity part extends outside the cavity to prevent excessive linear slope increase, thereby segmenting the tuning function to resolve the contradiction between tuning capability and linearity

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Different parts of the tuning component have different conductivity properties: the high-conductivity part inside the cavity provides effective resonance tuning, while the non-conductivity part outside the cavity suppresses unwanted electromagnetic effects. This local differentiation of material properties allows simultaneous achievement of good tuning capability and linearity

Inventive Principle:
Principle #3Local quality

2Ease of operation

If conventional tuning structures are used, then the filter can be adjusted, but signal radiation is not effectively suppressed and the Q value of the cavity is low

Engineering Contradiction:
ImproveadjustabilityVSAvoidsignal radiation loss
Core Design Contradiction:
Ease of operationVSLoss of energy

Solution Approach 1:

The tuning component uses localized high-conductivity material inside the resonant cavity to concentrate electromagnetic energy and suppress radiation losses. This localized conductivity enhancement increases the Q value of the cavity while maintaining adjustability through the non-conductivity part outside the cavity

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The tuning component is constructed as a composite structure combining high-conductivity and non-conductivity materials. This composite design enables the component to simultaneously achieve effective signal confinement (high Q value) and mechanical adjustability, resolving the contradiction between ease of operation and energy loss

Inventive Principle:
Principle #40Composite materials

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 new design effectively suppresses signal radiation, significantly increases the Q value of a single cavity, and optimizes linearity, enhancing frequency tuning performance and reducing interference.

Implementation Method 1

The tuning component may include a high-conductivity part and a non-conductivity part

Methodology Applied
Scientific EffectElectrical Conductivity: Conduction (electrical)

Implementation Method 2

effectively suppresses outward radiation of a signal

Methodology Applied
Scientific EffectElectromagnetic radiation suppression: Faraday Cage

Implementation Method 3

A function of each cavity is equivalent to an electronic oscillation circuit. When the filter is tuned to a proper wavelength of a received signal, the oscillation circuit may be represented as a parallel oscillation circuit including an inductance part and a capacitance part

Methodology Applied
Scientific EffectResonance: Resonance

Implementation Method 4

an electric field is formed in the resonant cavity. The tuning component may move along an electric field direction, to implement a tuning function

Methodology Applied
Scientific EffectElectric field distribution: Electric Field

Data Source

PatentEP3713011B1Cavity filter
Publication Date: 2026.03.25 HUAWEI TECH CO LTD
  • EP3713011B1 patent drawingFigure 1
  • EP3713011B1 patent drawingFigure 2~3
  • EP3713011B1 patent drawingFigure 4

AI summary

This application relates to the field of communications devices, and discloses a cavity filter. The cavity filter includes: a cavity, a cover plate, a tuning component, and a resonant column, where the cover plate is connected to the cavity, and the cover plate is configured to cover the cavity to form a resonant cavity. A through hole is provided on the cover plate, and the tuning component passes through the through hole and is fastened on the cover plate. The tuning part includes a high-conductivity part and a non-conductivity part, the high-conductivity part is located in the cavity, and the resonant column is mounted in the cavity. The cavity filter disclosed in this application may effectively suppress outward radiation of a signal, greatly increase a Q value of a single cavity, and optimize linearity.