Microstrip Circulator Housing Elimination via PCB Ground Members

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Solution Overview

Problem

Current below resonance circulators face challenges such as fragile leads, increased signal loss due to interface issues, and high manufacturing costs associated with precise housing requirements, which affect their performance and compatibility with packaging and shipping.

Innovation Solution

A microstrip circulator design featuring a conductive carrier with six ground members, a non-metallized ferrite slab, and the use of microwave epoxy to bond components without an external housing, allowing for reduced component count and cost, while maintaining high performance and compatibility with tape and reel packaging.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stability of the object's composition

If a housing is used to maintain compression on the components, then the structural stability is improved, but the manufacturing cost increases due to small tolerance requirements

Engineering Contradiction:
Improvestructural stabilityVSAvoidmanufacturing cost
Core Design Contradiction:
Stability of the object's compositionVSEase of manufacture

Solution Approach 1:

The patent removes the housing from the circulator assembly, extracting the compression function to be performed by the PCB itself through its ground members and mounting structure. This eliminates the need for a separate housing component while maintaining the necessary compression on the ferrite disc and other components.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The PCB is given multiple functions: it serves as the mounting substrate, provides ground members for electrical connection, and acts as the compression structure that replaces the housing. This multi-functionality reduces the overall component count and manufacturing complexity.

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

2Ease of operation

If the circulator is designed for surface mount with bent leads, then the ease of mounting is improved, but the reliability deteriorates due to fragile leads

Engineering Contradiction:
Improveease of mountingVSAvoidlead durability
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The patent removes the traditional bent lead structure from the circulator design. Instead, the circulator is mounted directly to the PCB through soldering of its terminal structures to the PCB ground members, eliminating the fragile bent leads that limited packaging and shipping options.

Inventive Principle:
Principle #2Taking out (Extraction)

3Adaptability or versatility

If via holes are used to transfer RF signal on PCB, then the adaptability is improved, but the loss of energy increases due to signal mismatch

Engineering Contradiction:
ImprovePCB integrationVSAvoidsignal loss
Core Design Contradiction:
Adaptability or versatilityVSLoss of energy

Solution Approach 1:

The patent uses ground members on the PCB as intermediary structures that provide both mechanical support and electrical connection for RF signal transfer. These ground members create direct solder joints between the circulator terminals and the PCB, serving as an effective intermediary that maintains signal integrity better than via holes.

Inventive Principle:
Principle #24Intermediary (Mediator)

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 reduces manufacturing costs, enhances component durability, and maintains high performance across a wide frequency range (2 GHz to 30 GHz) by eliminating the need for a housing and minimizing signal loss, making it suitable for radio and radar frequency applications.

Implementation Method 1

various components bonded together using the microwave epoxy

Methodology Applied
Scientific EffectAdhesive bonding: Adhesive

Implementation Method 2

A magnet and a fourth epoxy positioned between the insulator and the magnet

Methodology Applied
Scientific EffectMagnetic field: Magnetic Field

Data Source

PatentEP3459139B1Below resonance circulator and method of manufacturing the same
Publication Date: 2021.09.22 TRAK MICROWAVE LTD
  • EP3459139B1 patent drawingFigure 1
  • EP3459139B1 patent drawingFigure 2
  • EP3459139B1 patent drawingFigure 3

AI summary

A microstrip circulator includes a carrier and a ferrite slab having a first side and a second side. The circulator further includes a first microwave epoxy positioned between the carrier and the first side of the ferrite slab. The circulator further includes a conductor having a center portion with three legs extending therefrom. The circulator further includes a second microwave epoxy positioned between the second side of the ferrite slab and the conductor. The circulator further includes an insulator and a third microwave epoxy positioned between the conductor and the insulator. The circulator further includes a magnet and a fourth epoxy positioned between the insulator and the magnet.