Waveguide Flange Recess Geometry for Gap-Tolerant Leakage Control

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Solution Overview

Problem

Existing waveguide tube connecting methods fail to completely eliminate gaps between waveguide tubes, leading to radio wave leakage due to mechanical tolerances, even when fastened with flanges and fasteners.

Innovation Solution

The waveguide tube connecting member features a flange with a recessed second flange outer peripheral surface, where the electric length from the flange end surface to this surface is set to (2×N+1)/4 times the free space wavelength, ensuring that any gap formed between connected tubes suppresses radio wave leakage by making the oscillating electric field a node at the flange end and an antinode on the recessed surface.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If flanges of waveguide tubes are fastened with fasteners to reduce gaps, then mechanical connection strength is improved, but mechanical tolerances still cause gaps to exist leading to radio wave leakage

Engineering Contradiction:
Improveconnection strengthVSAvoidradio wave leakage prevention
Core Design Contradiction:
StrengthVSReliability

Solution Approach 1:

The patent converts the harmful effect of gaps (caused by mechanical tolerances) into a beneficial structure by designing a recessed portion in the flange that intentionally accommodates the gap. This recessed portion is positioned to create a specific electric field distribution that suppresses radio wave leakage, thereby transforming the tolerance-induced gap from a defect into a functional feature that maintains both mechanical strength and electromagnetic sealing.

Inventive Principle:
Principle #22Blessing in disguise (Convert harm into benefit)

2Reliability

If mechanical tolerances are reduced to eliminate gaps, then radio wave leakage is suppressed, but manufacturing complexity and cost increase

Engineering Contradiction:
Improveradio wave leakage preventionVSAvoidflange manufacturing tolerance
Core Design Contradiction:
ReliabilityVSManufacturing precision

Solution Approach 1:

The patent changes the geometric parameter of the flange by introducing a recessed portion with a specifically designed depth. This recessed depth parameter is optimized to accommodate normal manufacturing tolerances while maintaining the electromagnetic field distribution necessary to suppress radio wave leakage. By adjusting this geometric parameter, the system achieves reliable performance without requiring extremely tight manufacturing tolerances.

Inventive Principle:
Principle #35Parameter changes

3Reliability

If a recessed portion is added to the flange to suppress radio wave leakage, then electromagnetic sealing is improved, but device complexity increases

Engineering Contradiction:
Improveradio wave leakage preventionVSAvoidflange structure complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent applies local quality by introducing the recessed portion only at specific locations on the flange where gap formation most significantly affects radio wave leakage. Rather than redesigning the entire flange structure, the recessed portions are strategically positioned to create the necessary electric field distribution locally, thereby suppressing leakage with minimal additional structural complexity.

Inventive Principle:
Principle #3Local quality

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 radio wave leakage even when gaps exist between connected waveguide tubes, enhancing the mechanical design flexibility and assembly ease by tolerating increased mechanical part tolerances.

Implementation Method 1

The electric length from the first opening end of the flange end surface to the second flange outer peripheral surface along the tube radial direction is (2×N+1)/4 times a free space wavelength λ0, and N is an integer of 0 or more... making the oscillating electric field a node at the flange end and an antinode on the recessed surface

Methodology Applied
Scientific EffectStanding wave: Resonance

Data Source

PatentEP4287393A1Waveguide tube connecting member
Publication Date: 2023.12.06 FURUNO ELECTRIC CO LTD
  • EP4287393A1 patent drawingFigure 1
  • EP4287393A1 patent drawingFigure 2
  • EP4287393A1 patent drawingFigure 3

AI summary

A waveguide tube connecting member includes a first waveguide tube (1) having a first waveguide path (10) and a flange (11). The flange (11) has a flange end surface (13) extending from a first opening end (13) of the first waveguide path (10) toward an outer side in a tube radial direction (RD), and a second flange outer peripheral surface (15) which is a part of a first flange outer peripheral surface. The second flange outer peripheral surface is a surface (11) formed in a shape in which a part of the flange has a cavity. An electric length from the first opening end (10a) of the flange end surface (13) to the second flange outer peripheral surface (15) along the tube radial direction is (2×N+1)/4 times a wavelength.