Impedance Matching Line Transformer with Ferrite Damping

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Solution Overview

Problem

Existing impedance transformers are not suitable for high-frequency applications beyond the shortwave range due to dimensional limitations, and they generate excessive heat that can lead to component destruction, especially in power amplifiers.

Innovation Solution

A line transformer design featuring identical high-frequency line sections made as printed lines, routed through a ferrite body for damping standing waves, with a heat sink for efficient heat dissipation and a common ferrite body surrounding multiple line sections to prevent unwanted coupling, allowing for adjustable transformation ratios and impedance matching across a wide frequency range.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If conductor tracks are looped through a ferrite core multiple times to achieve impedance transformation, then the transformation ratio is achieved, but the transformer dimensions become too large for microwave frequency applications

Engineering Contradiction:
Improveimpedance transformation ratioVSAvoidtransformer length
Core Design Contradiction:
Measurement precisionVSLength of stationary object

Solution Approach 1:

The transformer is divided into multiple identical high-frequency line sections (first line section, second line section, etc.) that can be independently designed and manufactured. Each section has the same physical dimensions but contributes differently to the overall transformation ratio through their connection configuration (series/parallel arrangements), eliminating the need for multiple loops through a ferrite core.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Instead of achieving transformation through repeated loops in one dimension (length), the patent uses the dimension of connection topology (series/parallel configurations of identical sections) to achieve the same transformation effect with much shorter physical length.

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

2Reliability

If ferrite body is used to damp standing waves in high-frequency line sections, then signal quality is improved, but excessive heat is generated that can destroy the transformer

Engineering Contradiction:
Improvesignal qualityVSAvoidferrite body temperature
Core Design Contradiction:
ReliabilityVSTemperature

Solution Approach 1:

The harmful heat generated in the ferrite body is extracted and removed from the system by providing a dedicated heat sink that is thermally coupled to the ferrite body, separating the heat dissipation function from the signal processing function.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

A heat sink is introduced as an intermediary component between the ferrite body and the environment, facilitating efficient heat transfer from the ferrite body to the surrounding air or cooling medium.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Adaptability or versatility

If multiple high-frequency line sections are used for impedance matching, then broadband capability is achieved, but manufacturing complexity increases

Engineering Contradiction:
Improvebroadband capabilityVSAvoidnumber of line sections
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

All high-frequency line sections are designed to be identical in terms of physical dimensions, impedance characteristics, and construction. This homogeneity simplifies manufacturing as all sections can be produced using the same process and then connected in different configurations to achieve various transformation ratios and broadband performance.

Inventive Principle:
Principle #33Homogeneity

4Adaptability or versatility

If high-frequency line sections are arranged in parallel over minimum length, then broadband capability is enhanced, but heat dissipation becomes more difficult

Engineering Contradiction:
Improvebroadband capabilityVSAvoidheat dissipation efficiency
Core Design Contradiction:
Adaptability or versatilityVSLoss of energy

Solution Approach 1:

The ferrite body serves multiple functions simultaneously: it dampens standing waves in all parallel line sections, providing signal quality improvement, while also serving as a heat generation source that is thermally coupled to the heat sink for efficient heat dissipation from all sections.

Inventive Principle:
Principle #6Universality (Multi-functionality)

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 enhances manufacturing reliability and reduces production costs by enabling impedance matching in high-frequency applications, including the microwave range, while effectively managing heat generation and preventing component damage.

Implementation Method 1

At least one of the strip lines is routed through a ferrite body for damping standing waves

Methodology Applied
Scientific EffectMagnetic hysteresis: Magnetic Hysteresis

Implementation Method 2

The dissipation of the resulting heat to the environment can be improved by providing a heat sink connected to the ferrite body

Methodology Applied
Scientific EffectThermal conduction: Conduction (thermal)

Implementation Method 3

A standard heat sink can be attached to this flat contact surface

Methodology Applied
Scientific EffectThermal convection: Convection

Data Source

PatentEP1913606B1Line transformer for impedance matching
Publication Date: 2009.08.19 ROHDE & SCHWARZ GMBH & CO KG
  • EP1913606B1 patent drawingFigure 1
  • EP1913606B1 patent drawingFigure 2
  • EP1913606B1 patent drawingFigure 3~4

AI summary

The invention relates to a line transformer for impedance matching in high-frequency applications. The line transformer (1') comprises at least one first high-frequency line section (2) and a second high-frequency line section (3). At least one of the high-frequency line sections (2, 3) is surrounded by a ferrite body (12), the high-frequency line sections (2, 3) being provided in the form of microstrip lines between a first connection (10) and a second connection (11). The high-frequency line sections (2, 3, 29) have an essentially identical impedance.