Microwave Tube Output Power Equalization via Impedance Tuning

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Solution Overview

Problem

Existing microwave tubes with multiple high frequency output sections coupled to an output cavity face challenges in maintaining equal output power due to mechanical dimension variations, dielectric member permittivity changes, and waveguide deformations, leading to increased VSWR and power differences between sections.

Innovation Solution

Incorporation of an output power adjusting mechanism within the tube wall of each high frequency output section, allowing for displacement of a reflection adjusting part to adjust the load impedance by varying the coupling quantity, effectively matching output powers between sections without the need for a power mixer/divider.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If multiple high frequency output sections are coupled to the output cavity, then the power handling capability is improved, but the output power balance between sections deteriorates due to mechanical dimension variations and dielectric member permittivity changes

Engineering Contradiction:
Improvepower handling capabilityVSAvoidoutput power balance
Core Design Contradiction:
PowerVSManufacturing precision

Solution Approach 1:

The patent introduces adjustable tuning mechanisms (tuning pistons or movable walls) in each high frequency output section that allow dynamic adjustment of the output impedance. This enables compensation for manufacturing variations and maintains output power balance across multiple sections without requiring extremely tight manufacturing tolerances.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent changes the electrical parameters (impedance, phase) of each output section independently through adjustable tuning elements. By varying these parameters, the output power from each section can be equalized even when mechanical dimensions and dielectric properties vary during manufacturing.

Inventive Principle:
Principle #35Parameter changes

2Manufacturing precision

If a power mixer/divider is used to equalize output powers, then the output power balance is improved, but the external dimension of the klystron increases

Engineering Contradiction:
Improveoutput power balanceVSAvoidexternal dimension
Core Design Contradiction:
Manufacturing precisionVSLength of stationary object

Solution Approach 1:

The patent merges the power balancing function directly into the output sections by integrating adjustable tuning mechanisms within each section's waveguide or transmission line structure. This eliminates the need for separate external power mixer/divider components, thereby maintaining compact dimensions while achieving output power equalization.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The adjustable tuning mechanisms serve multiple functions: they control output power levels, match impedance, and compensate for manufacturing variations all within the existing output section structure. This multi-functionality removes the need for additional dedicated power balancing components.

Inventive Principle:
Principle #6Universality (Multi-functionality)

3Manufacturing precision

If the coupling parts and high frequency windows are made electrically identical, then the output power balance is improved, but the adaptability to manufacturing variations deteriorates

Engineering Contradiction:
Improveoutput power balanceVSAvoidtolerance to manufacturing variations
Core Design Contradiction:
Manufacturing precisionVSAdaptability or versatility

Solution Approach 1:

The patent transforms static, fixed coupling parts into dynamic structures with adjustable tuning elements. This allows the system to adapt to manufacturing variations by adjusting the electrical characteristics of each output section independently, rather than relying on identical fixed designs that are sensitive to tolerances.

Inventive Principle:
Principle #15Dynamics

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

Enables easy adjustment of high frequency output powers to achieve equalization between sections, reducing VSWR and eliminating the need for external power mixers/dividers, thereby minimizing the external dimensions of the microwave tube.

Implementation Method 1

displacement of a reflection adjusting part provided in the tube wall of an output tube in the inward or outward direction of the output tube to adjust the load impedance by varying the coupling quantity

Methodology Applied
Scientific EffectImpedance matching: Electrical Resistance

Data Source

PatentEP1826805B1Microwave tube
Publication Date: 2013.01.09 TOSHIBA ELECTRON TUBES & DEVICES CO LTD
  • EP1826805B1 patent drawingFigure 1~3
  • EP1826805B1 patent drawingFigure 4
  • EP1826805B1 patent drawingFigure 5~7

AI summary

An output power adjusting mechanisms (44) for adjusting output power is provided on a wave guide (38) of a high frequency output section (19) coupled to an output cavity (24). The output power adjusting mechanisms (44) is located at a position apart away from the output cavity (24) by a distance of 1/8 wavelength or [(1/8 wavelength) × odd number]. The output power adjusting mechanism (44) includes a reflection adjusting part (46) which is provided in the tube wall of the output tube (38) so as to be displaceable in the inward and outward directions of the output tube (38). The output power is adjusted by displacing the reflection adjusting part (46).