Ridged Serpentine Waveguide Applicator for Microwave Heating

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Solution Overview

Problem

Conventional rectangular serpentine waveguides for microwave heating, drying, or curing suffer from reduced efficiency, uniformity, and controllability due to coupling between consecutive waveguides and arcing at slot corners, leading to unwanted reflections.

Innovation Solution

A serpentine waveguide applicator with conductive ridges at the corners of a rectangular cross-section waveguide passes, which reduces microwave energy at the slots and minimizes arcing by focusing energy away from the slots, and chokes to prevent leakage, ensuring better isolation and reduced crosstalk between waveguide passes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If conventional rectangular serpentine waveguides with slots are used, then material can be exposed to microwave energy, but coupling between consecutive waveguides decreases efficiency and uniformity

Engineering Contradiction:

Improveheating efficiencyVSAvoidheating uniformity

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The waveguide is divided into multiple separate waveguide passes arranged side by side, each handling a portion of the material flow. This segmentation isolates the microwave fields in each pass, preventing coupling between consecutive waveguides while maintaining overall heating efficiency and uniformity across the material stream.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Tunnels are introduced as intermediary structures between facing waveguide passes to enclose the material and prevent direct coupling between adjacent waveguides. These tunnels act as electromagnetic barriers that isolate the microwave fields while still allowing the material to pass through continuously.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Ease of operation

If slots are used in conventional waveguides, then material exposure is enabled, but arcing at slot corners causes unwanted reflections

Engineering Contradiction:

Improvematerial exposure capabilityVSAvoidsignal stability

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

Ridges are added locally at the corner regions of the waveguide passes where arcing occurs. These corner ridges modify the electromagnetic field distribution in the critical corner areas, reducing field concentration and preventing arcing while maintaining the slot functionality for material exposure.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The ridges at the corners, which initially might be seen as structural additions, actually convert the harmful arcing effect into a beneficial field distribution pattern. The ridges guide the microwave fields away from the slot corners, eliminating reflections while maintaining efficient energy transfer.

Inventive Principle:

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

3Productivity

If waveguide passes are arranged side by side, then material flow is improved, but coupling between passes reduces controllability

Engineering Contradiction:

Improvematerial throughputVSAvoidheating controllability

Core Design Contradiction:

ProductivityVSEase of operation

Solution Approach 1:

The side-by-side arrangement of multiple waveguide passes segments the material flow into parallel channels, increasing throughput capacity. The tunnels between passes provide electromagnetic isolation, ensuring that each pass can be independently controlled for precise heating regulation while maintaining high material throughput.

Inventive Principle:

Principle #1Segmentation

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 enhances the efficiency, uniformity, and controllability of microwave heating, drying, or curing processes by reducing electric field gradients at the slots, minimizing arcing, and decreasing microwave leakage, resulting in improved material processing outcomes.

Implementation Method 1

The ridges reduce the microwave energy at the slots in the waveguide passes

Methodology Applied

Scientific EffectElectromagnetic field distribution: Electric Field

Implementation Method 2

Waveguide bends connect the waveguide passes in series so that microwave energy flows in opposite directions in consecutive waveguide passes

Methodology Applied

Scientific EffectWaveguide propagation: Waveguide

Implementation Method 3

A microwave energy source coupled to the first end of the serpentine waveguide supplies microwave energy flowing through the serpentine waveguide to the second end to heat the material advancing through the applicator portion

Methodology Applied

Scientific EffectDielectric heating: Dielectric Heating

Implementation Method 4

Chokes around the entrance and exit slots decrease the leakage of microwave energy through the slots

Methodology Applied

Scientific EffectElectromagnetic shielding: Faraday Cage

Data Source

PatentUS7368692B1Ridged serpentine waveguide applicator

Publication Date: 2008.05.06 MICROWAVE TECHNIQUES LLC

AI summary

A serpentine waveguide applicator for exposing a material to microwave energy for hearing, drying, or curing. A conveyor transports the material through aligned slots formed in facing sides at consecutive waveguide passes of the serpentine array. Each pass has a ridged waveguide structure with ridges in each corner of the otherwise rectangular waveguide. The ridges make the interior cross section of the waveguide passes cruciform and direct microwave energy away from the slots to reduce arcing, crosstalk, and leakage.