Broadband Microstrip Ferrite Circulator With Low-Loss Adhesive Bonding

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Solution Overview

Problem

Conventional circulators exhibit high field loss outside a narrow bandwidth and are prone to damage during processing due to low-temperature curing of epoxy.

Innovation Solution

A broadband microstrip ferrite circulator design with a non-metallized ferrite disc and independent center conductor, using low-loss microwave adhesives to bond components without a housing, allowing processing at higher temperatures and enabling a broader bandwidth of 4 GHz to 18 GHz with reduced field loss.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional circulator design is used, then the circulator can be manufactured with traditional epoxy curing, but the circulator suffers from high field loss outside narrow bandwidth and damage during processing

Engineering Contradiction:

Improvestructural integrity during processingVSAvoidbandwidth range

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The patent changes the curing temperature parameter from low (conventional epoxy) to high (125°C-150°C), enabling the use of high-temperature adhesives that provide both structural integrity during processing and support for broadband operation. This parameter change resolves the contradiction between structural reliability and bandwidth adaptability.

Inventive Principle:

Principle #35Parameter changes

2Ease of manufacture

If low-temperature epoxy curing is used, then the circulator can be processed at lower temperatures, but the circulator is damaged during processing and has narrow bandwidth

Engineering Contradiction:

Improveprocessing temperatureVSAvoidstructural integrity during processing

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The patent raises the processing temperature parameter from conventional low-temperature epoxy curing to high-temperature curing (125°C-150°C), enabling the use of high-temperature adhesives that provide superior structural integrity while avoiding damage during subsequent processing operations.

Inventive Principle:

Principle #35Parameter changes

3Reliability

If high-temperature processing is used, then the circulator can withstand processing without damage, but the epoxy may be damaged at high temperatures

Engineering Contradiction:

Improvestructural integrity during processingVSAvoidepoxy damage from high temperature

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent replaces the conventional low-temperature epoxy (which is damaged at high temperatures) with high-temperature adhesives that are specifically designed to withstand curing temperatures of 125°C-150°C and subsequent processing, eliminating the harmful effect of temperature-induced epoxy damage.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

4Object-affected harmful factors

If conventional circulator design with housing is used, then structural protection is provided, but manufacturing cost increases and tape and reel packaging compatibility is reduced

Engineering Contradiction:

Improvestructural protectionVSAvoidmanufacturing cost and packaging compatibility

Core Design Contradiction:

Object-affected harmful factorsVSEase of manufacture

Solution Approach 1:

The patent extracts and eliminates the housing component from the conventional circulator design, relying instead on high-temperature adhesives to provide structural bonding and protection. This extraction reduces manufacturing cost and enables tape and reel packaging compatibility while maintaining structural integrity through the adhesive bonding system.

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 design achieves low field loss over a wide bandwidth and withstands processing without structural damage, reducing manufacturing costs and enabling tape and reel packaging compatibility.

Implementation Method 1

a magnet. The broadband microstrip ferrite circulator or isolator further includes a spacer positioned between the conductor and the magnet

Methodology Applied

Scientific EffectMagnetic field: Magnetic Field

Implementation Method 2

a ferrite disc positioned within the opening of the dielectric substrate

Methodology Applied

Scientific EffectFaraday effect: Faraday Effect

Data Source

PatentEP3724947B1Broadband circulator and method of manufacturing the same

Publication Date: 2025.08.06 TRAK MICROWAVE LTD

Figure 1~2
Figure 3

AI summary

A broadband microstrip ferrite circulator or isolator includes a carrier. The broadband microstrip ferrite circulator or isolator further includes a dielectric substrate having an opening therein. The broadband microstrip ferrite circulator or isolator further includes a ferrite disc positioned within the opening of the dielectric substrate. The broadband microstrip ferrite circulator or isolator further includes a conductor having three contacts extending therefrom, the conductor being positioned on the ferrite disc. The broadband microstrip ferrite circulator or isolator further includes a magnet. The broadband microstrip ferrite circulator or isolator further includes a spacer positioned between the conductor and the magnet.