Waveguide Substrate Thickness Control for Low-Loss THz Transmission
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Solution Overview
Problem
Current waveguide elements experience significant propagation loss when guiding millimeter wave/terahertz waves, particularly at frequencies above 30 GHz, due to increased slab mode induction and substrate resonance.
Innovation Solution
A waveguide element design utilizing an inorganic material substrate with a thickness that satisfies the expression t < λaε, where 't' is the substrate thickness, 'λ' is the electromagnetic wave wavelength, 'ε' is the relative dielectric constant, and 'a' is a value of 3 or more, combined with a conductor layer and a supporting substrate configuration that suppresses slab mode and substrate resonance, thereby reducing propagation loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a transparent substrate with thickness of 2 mm is used in the waveguide element, then the mechanical strength is improved, but the propagation loss is remarkably increased due to slab mode induction and substrate resonance at frequencies above 30 GHz
Solution Approach 1:
The patent applies parameter changes by precisely controlling the substrate thickness to satisfy the inequality t < λ/(a√εr), where t is thickness, λ is wavelength, εr is relative dielectric constant, and a ≥ 3. This mathematical constraint transforms the substrate thickness from a fixed mechanical parameter to a frequency-dependent parameter that simultaneously satisfies both mechanical strength requirements and propagation loss reduction requirements at millimeter wave frequencies.
Solution Approach 2:
The patent applies local quality by using different materials for the substrate and supporting substrate. The waveguide substrate is made of a material with specific dielectric properties (εr and tanδ) optimized for low propagation loss, while the supporting substrate is made of a different material optimized for mechanical support. This material differentiation allows each component to be optimized for its specific function without compromising the other.
2Loss of energy
If the substrate thickness is reduced to reduce propagation loss, then the propagation loss is reduced, but the mechanical strength is weakened
Solution Approach 1:
The patent applies segmentation by dividing the support function from the waveguide function. The thin waveguide substrate (satisfying t < λ/(a√εr)) is separated from the supporting substrate, with the latter providing mechanical strength and the former providing low-loss waveguide properties. This functional segmentation allows each substrate to be optimized independently for its specific purpose.
Solution Approach 2:
The patent applies composite materials by creating a layered structure combining the waveguide substrate and supporting substrate. The composite structure integrates materials with different properties: the waveguide substrate material optimized for electromagnetic wave propagation (low tanδ) and the supporting substrate material optimized for mechanical strength, achieving both low propagation loss and sufficient mechanical strength simultaneously.
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 waveguide element achieves excellent low-propagation loss performance by stabilizing the reduction of propagation loss even at high frequencies, enabling efficient transmission of electromagnetic waves up to 20 THz with reduced slab mode and substrate resonance.
Implementation Method 1
an inorganic material substrate; and a conductor layer arranged above the inorganic material substrate. A thickness "t" of the inorganic material substrate satisfies the following expression (1): t < λ/(a√ε) where ε represents a relative dielectric constant of the inorganic material substrate
Implementation Method 2
a waveguide member capable of guiding an electromagnetic wave having a frequency of 30 GHz or more and 20 THz or less
Data Source
AI summary
A waveguide element includes a waveguide member capable of guiding an electromagnetic wave having a frequency of 30 GHz or more and 20 THz or less. The waveguide member includes: an inorganic material substrate; and a conductor layer arranged above the inorganic material substrate. A thickness “t” of the inorganic material substrate satisfies the following expression (1):t<λaε(1)where “t” represents the thickness of the inorganic material substrate, λ represents a wavelength of an electromagnetic wave to be guided by the waveguide member, ε represents a relative dielectric constant of the inorganic material substrate, and “a” represents a numerical value of 3 or more.