Liquid Crystal Phase Shifter for Low Power Microwave Systems

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Solution Overview

Problem

Existing phase shifters in microwave systems face challenges with high power requirements, significant losses during operation, and high fabrication costs, while seeking improvements in phase shifting capabilities.

Innovation Solution

A liquid crystal (LC) layer-based phase shifter apparatus with a bias line coupled to an electrode, where the LC layer fills a compartment within a waveguide structure, utilizing alignment chemical coatings to orient LC molecules for efficient permittivity tuning, and a method for fabricating the phase shifter using multi-layer printed circuit board techniques to integrate with substrate integrated waveguides.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If active components such as transistors and diodes are used in phase shifters, then phase shifting capability is achieved, but power consumption increases and losses occur during operation

Engineering Contradiction:
Improvepower consumptionVSAvoidoperational losses
Core Design Contradiction:
PowerVSReliability

Solution Approach 1:

The patent replaces active electronic components (transistors, diodes) with a passive liquid crystal-based phase shifting mechanism. The liquid crystal layer, when subjected to an electric field, changes its permittivity to alter the phase of microwave signals without requiring active power consumption or generating significant losses, thus resolving the contradiction between achieving phase shifting capability and minimizing power consumption and operational losses.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Ease of manufacture

If conventional phase shifter technologies are used, then phase shifting is achieved, but fabrication costs increase

Engineering Contradiction:
Improvefabrication costVSAvoidphase shifting performance
Core Design Contradiction:
Ease of manufactureVSManufacturing precision

Solution Approach 1:

The patent utilizes the tunable permittivity parameter of liquid crystal materials to achieve phase shifting. By applying different voltages to the liquid crystal layer, the permittivity changes, which in turn adjusts the phase of the microwave signal. This parameter-based approach allows for cost-effective fabrication using standard waveguide structures combined with liquid crystal compartments, avoiding the need for expensive active components while maintaining precise phase control.

Inventive Principle:
Principle #35Parameter changes

3Adaptability or versatility

If liquid crystal is used to fill the compartment, then permittivity tuning capability is achieved, but molecular alignment control becomes necessary

Engineering Contradiction:
Improvepermittivity tuning rangeVSAvoidalignment control mechanism
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent applies alignment chemicals to the compartment surfaces before filling with liquid crystal. These pre-applied alignment layers establish the initial molecular orientation of the liquid crystal, ensuring proper permittivity tuning behavior when voltage is applied. This preliminary action simplifies the overall device structure by eliminating the need for complex real-time alignment control mechanisms, as the alignment is established during fabrication.

Inventive Principle:
Principle #10Preliminary 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 solution achieves low power consumption, reduced losses, and enhanced phase tuning range with lower fabrication costs, enabling efficient microwave signal processing and integration with waveguides.

Implementation Method 1

A phase shifter apparatus includes a liquid crystal (LC) layer... where the LC layer fills a compartment... utilizing alignment chemical coatings to orient LC molecules for efficient permittivity tuning

Methodology Applied
Scientific EffectPermittivity tuning: Dielectric Permittivity

Implementation Method 2

A bias line is coupled to the electrode... in the absence of an applied static electric field, align molecules in an orientation that is parallel to a plane of the electrode

Methodology Applied
Scientific EffectLiquid crystal response to electric field: Electro-Optic Effects

Implementation Method 3

At least one alignment chemical coating may be applied on at least one surface of the compartment. The at least one alignment chemical coating may be selected to, in the absence of an applied static electric field, align molecules in an orientation that is parallel to a plane of the electrode

Methodology Applied
Scientific EffectMolecular alignment:

Data Source

PatentEP3224898B1System and method for variable microwave phase shifter
Publication Date: 2020.09.02 HUAWEI TECH CO LTD
  • EP3224898B1 patent drawingFigure 1A
  • EP3224898B1 patent drawingFigure 1B~1C
  • EP3224898B1 patent drawingFigure 1D~1E

AI summary

A phase shifter and a method of making a phase shifter are disclosed herein. The phase shifter may include a housing, a dielectric, an electrode, and a liquid crystal layer. The housing includes first, second, third, and fourth conductive walls, each conductive wall being opposite one of the other walls. The dielectric is situated within the housing and defines a compartment within the housing. The electrode is aligned with the compartment. The liquid crystal layer fills the space of the compartment. A bias line is coupled to the electrode. The phase shifter may be integrated with as substrate integrated waveguide.