Reciprocal Ferrite Switch Layout With Low Insertion Loss

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Solution Overview

Problem

High-frequency switches, particularly ferrite switches, face challenges with complex structures and high insertion losses, which affect the performance of high-frequency communication systems. Additionally, ferrite switches lack reciprocity between ports, limiting their flexibility.

Innovation Solution

A ferrite switch is designed using a combination of a coupler, two ferrite circulators connected to short-circuit loads, and a magic T. By controlling the magnetic field bias states of the ferrite circulators, the switch achieves a reciprocal function while maintaining low insertion loss characteristics.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a Y-junction combined ferrite switch or differential phase-shift ferrite switch is used to achieve reciprocity, then reciprocity between ports is improved, but device complexity increases due to additional transmission links and phase shifters

Engineering Contradiction:
ImprovereciprocityVSAvoidstructure
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent combines a magic T junction and ferrite circulators into an integrated reciprocal ferrite switch structure. The magic T junction integrates E-plane and H-plane waveguide junctions to combine signal paths, while ferrite circulators provide non-reciprocal phase shifting. This merging eliminates the need for separate phase shifters and transmission links required in conventional Y-junction or differential phase-shift designs, achieving reciprocity with reduced structural complexity

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The magic T junction serves multiple functions simultaneously: it acts as a power combiner, signal splitter, and provides the geometric structure for phase difference generation. The ferrite circulators provide both signal routing and phase control functions. This multi-functionality reduces the number of dedicated components needed, simplifying the overall device structure while maintaining reciprocity capability

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

2Adaptability or versatility

If a Y-junction combined ferrite switch or differential phase-shift ferrite switch is used to achieve reciprocity, then reciprocity between ports is improved, but insertion loss increases

Engineering Contradiction:
ImprovereciprocityVSAvoidinsertion loss
Core Design Contradiction:
Adaptability or versatilityVSLoss of energy

Solution Approach 1:

By merging the magic T junction with ferrite circulators, the patent creates a direct signal path that avoids the multiple transmission links and phase shifter connections required in conventional reciprocal switch designs. This reduces the number of interfaces and components where energy loss occurs, thereby reducing overall insertion loss while maintaining reciprocity

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The ferrite circulators maintain continuous signal flow through their non-reciprocal phase shifting capability, allowing signals to pass through with minimal disruption. The magic T junction provides continuous signal combining and splitting paths. This continuity reduces signal interruptions and re-reflections that would otherwise increase insertion loss in conventional switch architectures

Inventive Principle:
Principle #20Continuity of useful action

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 proposed ferrite switch improves performance by enabling reciprocal operation with low insertion loss, enhancing the flexibility and efficiency of high-frequency communication systems.

Implementation Method 1

The ferrite circulator has first ports, second ports, and third ports... after the equi-amplitude in-phase or equi-amplitude phase-inverted power signals are input from the two input ports of the first magic T, the power signals are output from two output ports of the first magic T respectively

Methodology Applied
Scientific EffectMagnetoelectric effect: Magneto-Optic Effects

Data Source

PatentEP4120469B1Ferrite switch, microwave antenna, and electronic device
Publication Date: 2025.06.11 HUAWEI TECH CO LTD
  • EP4120469B1 patent drawingFigure 1~2
  • EP4120469B1 patent drawingFigure 3~4
  • EP4120469B1 patent drawingFigure 5

AI summary

This application provides a ferrite switch, a microwave antenna, and an electronic device. The ferrite switch includes a coupler, a first magic T, and two ferrite circulators. The ferrite circulators have first ports, second ports, and third ports, the second ports are connected to short-circuit loads, the first ports of the two ferrite circulators are respectively connected to two output ports of the coupler, the two output ports of the coupler are configured to output equi-amplitude in-phase or equi-amplitude phase-inverted power signals, and the third ports of the two ferrite circulators are respectively connected to two input ports of the first magic T; and after the equi-amplitude in-phase or equi-amplitude phase-inverted power signals are input from the two input ports of the first magic T, the power signals are output from two output ports of the first magic T respectively. Embodiments of this application provide a ferrite switch, a microwave antenna, and an electronic device, to resolve problems of a complicated structure and a high insertion loss of a reciprocal ferrite switch.