Microwave Filter Impedance Matching via Segmented Branch Widths
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing microwave filters are ineffective in significantly reducing electromagnetic interference (EMI) due to unoptimized impedance curves in transmission lines, leading to inadequate filtering effects.
Innovation Solution
A microwave filter design featuring a strip transmission line with a filtering assembly comprising primary and secondary branches of varying widths, arranged in specific configurations to match impedance curves with high-frequency EMI, enhancing the filtering effect and suppressing EMI.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If conventional transmission line design is used, then device complexity is low, but filtering effect is insufficient and EMI is not suppressed
Solution Approach 1:
The filtering assembly is segmented into multiple primary branches (first primary branch, second primary branch) connected to different connection points on the transmission line. Each primary branch can be further divided into secondary branches with varying widths, creating a segmented structure that provides multiple impedance matching points to suppress EMI across different frequency bands
Solution Approach 2:
Different sections of the filtering assembly have different local qualities through varying strip widths. The first primary branch has a first width, the second primary branch has a second width, and secondary branches have yet another width. This local quality variation creates different impedance characteristics at different locations, enabling effective EMI suppression across broad frequency ranges
2Object-affected harmful factors
If simple transmission line is used, then manufacturing is easy, but impedance curve matching with high-frequency EMI is insufficient
Solution Approach 1:
The filtering assembly utilizes parameter changes in strip width to achieve impedance curve matching. By varying the width of primary and secondary branches, the impedance characteristics are adjusted to match the impedance profile of high-frequency EMI, enabling effective suppression without complex manufacturing processes
3Object-affected harmful factors
If uniform width branches are used, then device complexity is low, but filtering effect across frequency bands is insufficient
Solution Approach 1:
The filtering assembly employs asymmetric branch width design where the first primary branch, second primary branch, and secondary branches all have different widths. This asymmetry creates varied impedance transformations across different frequency bands, enhancing the overall filtering effect compared to uniform width designs
Data Source
AI summary
A microwave filter includes a strip transmission line and a filtering assembly connected to the strip transmission line. The transmission line has an input terminal and an output terminal. The filtering assembly includes a strip first primary branch connected directly to a first connection point of the transmission line. The first primary branch includes a first body portion and a first bent portion at a first end of the first body portion, where the first bent portion is connected directly to the first connection point, and the first body portion is substantially parallel to a body portion of the transmission line. With the microwave filter incorporated in an electric motor, the impedance curve of the transmission line can be matched with a high-frequency EMI curve, and therefore the filtering effect is enhanced, EMI is suppressed and the EMC level improved.