Multilayer Waveguide Choke Structure for Leakage Suppression

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Solution Overview

Problem

Conventional waveguide connection structures experience leakage and transmission loss due to misalignment and warpage, leading to resonance in higher order modes, which degrades connection characteristics, especially in high-frequency bands like millimeter waves.

Innovation Solution

A waveguide connection structure featuring a choke structure with a rectangular conductor pattern and a closed-ended dielectric transmission path, forming a magnetic wall to suppress parallel plate mode and reduce leakage, allowing for better alignment independence and smaller size.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If a conventional choke structure with a groove of depth λ/4 is formed at a position λ/4 away from the E-plane edge, then the E-plane edge is closed-ended in a standing wave and leakage is reduced, but resonance in higher order modes occurs when waveguides are misaligned and connection characteristics are degraded

Engineering Contradiction:

Improvesignal leakageVSAvoidconnection characteristics

Core Design Contradiction:

Loss of energyVSReliability

Solution Approach 1:

The choke structure is segmented into multiple conductor patterns arranged in a specific configuration. Instead of using a single continuous groove, the invention divides the choke into discrete conductor patterns (e.g., rectangular or circular patterns) positioned at specific locations around the waveguide, which prevents the formation of resonant higher-order modes while maintaining the leakage suppression function.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The conductor patterns are strategically positioned at specific locations (e.g., at positions where the electric field is maximum) to locally suppress leakage without creating resonance conditions. The local electromagnetic field distribution is exploited to place conductor patterns where they provide maximum benefit while avoiding resonant interactions.

Inventive Principle:

Principle #3Local quality

2Reliability

If a choke groove is formed on the metal waveguide substrate, then connection characteristics are improved, but high-accuracy mechanical processing is required and manufacturing complexity increases

Engineering Contradiction:

Improveconnection characteristicsVSAvoidmechanical processing accuracy

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The invention replaces the mechanical groove formation process with a conductor pattern deposition process. Instead of mechanically machining a choke groove into the metal substrate, conductor patterns are formed using standard PCB fabrication techniques such as photolithography and electroplating, which are more tolerant of manufacturing variations and do not require high-precision mechanical processing.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The choke structure parameters are optimized to be less sensitive to manufacturing tolerances. The conductor patterns are designed with dimensions and positions that provide robust performance even with typical manufacturing variations, reducing the need for ultra-precise fabrication.

Inventive Principle:

Principle #35Parameter changes

3Loss of energy

If the multilayer dielectric substrate warpages, then a gap is formed between the conductor layer and waveguide substrate, causing parallel plate mode leakage and increased transmission loss

Engineering Contradiction:

Improvetransmission lossVSAvoidsubstrate flatness

Core Design Contradiction:

Loss of energyVSStability of the object's composition

Solution Approach 1:

The conductor patterns are positioned and designed to provide leakage suppression even when gaps are present due to substrate warpage. The choke structure is designed with sufficient margin to accommodate expected substrate deformations, cushioning against the adverse effects of warpage before they can significantly degrade performance.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

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 lower signal leakage and loss, preventing resonance-induced degradation in connection characteristics, even with misalignment, and reduces the size and weight of the choke structure, eliminating the need for high-accuracy mechanical processing.

Implementation Method 1

forming a magnetic wall to suppress parallel plate mode and reduce leakage

Methodology Applied

Scientific EffectMagnetic wall: Magnetic Field

Implementation Method 2

the E-plane edge of the waveguide is closed-ended in a standing wave from a closed-end point of a choke groove

Methodology Applied

Scientific EffectStanding wave: Resonance

Data Source

PatentUS8179214B2Waveguide connection between a multilayer waveguide substrate and a metal waveguide substrate including a choke structure in the multilayer waveguide

Publication Date: 2012.05.15 MITSUBISHI ELECTRIC CORP

AI summary

A rectangular conductor pattern is formed around a first waveguide on a multilayer dielectric substrate facing a metal substrate, with an end at about λ/4 away from a long side edge of the first waveguide, where μ is a free-space wavelength of a signal wave. A conductor opening is formed between the end of the conduction pattern and the long side edge of the first waveguide, with a length longer than a long side of the first waveguide and shorter than about λ. A closed-ended dielectric transmission path is formed in the multilayer dielectric substrate in the layer direction, with a length of about λg/4, where λg is an in-substrate effective wavelength of the signal wave.