Microwave Filter Stubs With Enlargements To Prevent Multipactor
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Solution Overview
Problem
Very high power microwave filters face the challenge of the multipactor effect, where electron avalanches occur due to electromagnetic field concentrations in vacuum environments, degrading performance and potentially leading to component destruction, especially in space applications where high transmission power is required.
Innovation Solution
The solution involves producing microwave waveguides with strategically located enlargements at specific distances from short-circuit zones in stubs, where energy concentrations are highest, to reduce electromagnetic field concentrations and prevent multipactor effects, while maintaining compatibility with existing manufacturing methods and frequency ranges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the walls of the waveguide are separated to increase V multi, then the multipactor threshold voltage increases, but the range of operating frequencies is reduced and the device has difficulties in adapting the guide for all frequencies
Solution Approach 1:
The patent applies local quality by introducing enlargements only at specific critical locations within the waveguide where electromagnetic field concentrations occur, rather than uniformly separating all walls. This localized modification increases the multipactor threshold voltage at problem areas while preserving the overall waveguide geometry and its broadband frequency adaptability.
2Reliability
If the topology of the devices is modified to reduce the concentration of the electric field, then the multipactor effect is reduced, but the device complexity increases and existing manufacturing methods cannot be used
Solution Approach 1:
The patent changes geometric parameters by introducing enlargements with specific dimensions and positions defined by mathematical relationships (e.g., distance from short-circuit zone, enlargement depth as fraction of wavelength). These parameter modifications reduce electric field concentration and multipactor effects while maintaining compatibility with existing waveguide manufacturing processes.
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 approach significantly increases multipactor power handling, reduces ohmic losses, and ensures compatibility with existing manufacturing methods, enabling high-power operation without electron avalanches, thus enhancing the reliability and efficiency of microwave filters.
Implementation Method 1
This multipactor effect is caused by a concentration of the electromagnetic field which pulls electrons from the walls of the guide
Implementation Method 2
The multipactor effect is caused by a concentration of the electromagnetic field which pulls electrons from the walls of the guide
Implementation Method 3
The electrons are then accelerated towards the opposite wall of the guide. The impact of these electrons on this wall in turn causes electron tearing and so on. There is thus an electron avalanche phenomenon
Data Source
Figure 1a~2
Figure 3~4b
Figure 5a~7c
AI summary
The invention concerns a method for making a microwave waveguide including: a step of determining the zone(s) (zl) of the guide (gl) where there is an electric field concentration, and a step of forming at least one enlargement (ell) of the waveguide in the zone(s) thus determined. The invention also concerns a microwave filter in which the stubs are provided with such enlargements. The invention is suitable for use in microwave filters.