Coplanar Waveguide Substrate Layout for Low Propagation Loss

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Solution Overview

Problem

Waveguide devices face challenges in achieving low-propagation loss performance over a wide frequency range, particularly in the high-frequency region of 30 GHz or more, when mounted on support substrates, due to issues like slab mode induction and substrate resonance.

Innovation Solution

A waveguide device configuration featuring an inorganic material substrate with coplanar electrodes and a low-dielectric constant portion, where the thickness of the inorganic material substrate is optimized to satisfy the condition t < λa⁢ε, and a recess in the support substrate forms a cavity to suppress slab mode and substrate resonance, ensuring low-propagation loss across a broad frequency range.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stability of the object's composition

If a waveguide device is mounted on a support substrate, then mechanical support and structural stability are improved, but propagation loss increases due to slab mode induction and substrate resonance

Engineering Contradiction:

Improvestructural stabilityVSAvoidpropagation loss

Core Design Contradiction:

Stability of the object's compositionVSLoss of energy

Solution Approach 1:

A low-dielectric constant portion is introduced as an intermediary layer between the inorganic material substrate and the support substrate. This intermediary structure suppresses slab mode induction and substrate resonance by providing a dielectric barrier, thereby reducing propagation loss while maintaining the mechanical support function of the support substrate

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The low-dielectric constant portion is specifically positioned in the region where electromagnetic fields interact with the support substrate, creating a localized zone with optimized dielectric properties. This local modification targets the problematic interaction area without changing the overall structural support configuration

Inventive Principle:

Principle #3Local quality

2Strength

If the thickness of the inorganic material substrate is increased, then mechanical strength is improved, but propagation loss increases due to enhanced slab mode and substrate resonance effects

Engineering Contradiction:

Improvemechanical strengthVSAvoidpropagation loss

Core Design Contradiction:

StrengthVSLoss of energy

Solution Approach 1:

The low-dielectric constant portion acts as a mediator that decouples the electromagnetic field interaction from the support substrate, allowing the inorganic material substrate to be thicker for mechanical strength without proportionally increasing propagation loss through slab mode and substrate resonance

Inventive Principle:

Principle #24Intermediary (Mediator)

3Device complexity

If conventional waveguide structures are used without low-dielectric constant portions, then device complexity is reduced, but propagation loss performance deteriorates in the high-frequency region of 30 GHz or more

Engineering Contradiction:

Improvestructure complexityVSAvoidpropagation loss

Core Design Contradiction:

Device complexityVSLoss of energy

Solution Approach 1:

The dielectric constant parameter is changed by introducing a low-dielectric constant portion with a dielectric constant lower than that of the inorganic material substrate. This parameter change targets the high-frequency region (30 GHz or more) to suppress propagation loss through reduced slab mode induction and substrate resonance

Inventive Principle:

Principle #35Parameter changes

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

This configuration effectively reduces propagation loss and maintains excellent low-propagation performance over a wide frequency range, including frequencies above 30 GHz, by minimizing electromagnetic wave leakage and dielectric loss.

Implementation Method 1

a low-dielectric constant portion... has a dielectric constant smaller than a dielectric constant of the inorganic material substrate

Methodology Applied

Scientific EffectDielectric loss: Dielectric Permittivity

Implementation Method 2

a recess in the support substrate forms a cavity to suppress slab mode and substrate resonance

Methodology Applied

Scientific EffectSubstrate resonance: Resonance

Data Source

PatentUS20240162592A1Waveguide device

Publication Date: 2024.05.16 NGK INSULATORS LTD

AI summary

A waveguide device includes: a waveguide member capable of guiding an electromagnetic wave having a frequency of 30 GHz or more and 20 THz or less; a support substrate configured to support the waveguide member; and a low-dielectric constant portion. The waveguide member includes: an inorganic material substrate; and coplanar electrodes arranged above the inorganic material substrate. The support substrate is arranged below the inorganic material substrate. The low-dielectric constant portion is arranged below the inorganic material substrate, and has a dielectric constant smaller than a dielectric constant of the inorganic material substrate.