Waveguide Filter Using Commensurate-Line Structures
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Solution Overview
Problem
Classical waveguide band-pass filters in high-frequency bands, such as Q/V/W bands, face challenges due to manufacturing tolerances, requiring high-precision and costly manufacturing processes, and are sensitive to imperfections, leading to time-consuming optimization and additional ohmic losses.
Innovation Solution
A novel band-pass filter design utilizing commensurate-line structures (CLS) and stub-modified commensurate-line structures (SMCLS) to provide multiple transmission zeros with reduced construction time and sensitivity to manufacturing tolerances, allowing for independent design and optimization of passbands and transmission zeros, resulting in a compact and efficient filtering solution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional coupled resonant cavities are used for waveguide BPFs in Q/V/W-bands, then better theoretical RF performance in terms of quality factor is achieved, but manufacturing precision requirements increase significantly and manufacturing cost increases
Solution Approach 1:
The patent transforms the filter design from traditional coupled resonant cavities to a stepped-impedance transmission line structure with artificial transmission zeros. This parameter change in topology allows achieving high rejection ratios through impedance discontinuities rather than relying solely on precise resonant cavity dimensions, thereby reducing manufacturing precision requirements while maintaining or improving Q-factor performance.
Solution Approach 2:
The filter is segmented into multiple sections with different impedance values (high-impedance and low-impedance sections) along the transmission path. Each segment contributes to creating specific transmission zeros at desired frequencies. This segmentation approach allows independent optimization of each section's impedance to achieve overall filter performance without requiring ultra-precise manufacturing of the entire structure.
2Reliability
If traditional coupled resonant cavities are used for waveguide BPFs in Q/V/W-bands, then better theoretical RF performance in terms of quality factor is achieved, but manufacturing time increases due to high-precision requirements and tuning screws
Solution Approach 1:
The filter design incorporates preliminary optimization during the design phase where the impedance values and section lengths are carefully calculated to achieve the desired transmission zeros and passband characteristics. This preliminary action ensures that the filter meets specifications without requiring post-manufacturing tuning with adjustment screws, thereby significantly reducing manufacturing time while maintaining high quality factor performance.
Solution Approach 2:
The patent adopts a design philosophy that accepts slightly lower individual section precision but achieves overall high performance through the cumulative effect of multiple impedance sections. This approach replaces expensive and time-consuming precision tuning mechanisms with a more robust, tolerance-friendly structure that can be manufactured quickly using standard techniques.
3Reliability
If additional coupled resonant cavities are added to provide multiple transmission zeros, then more transmission zeros are achieved, but device size increases and optimization complexity increases
Solution Approach 1:
The stepped-impedance transmission line structure serves multiple functions simultaneously: it provides the main filter passband response, creates multiple transmission zeros at different frequencies through impedance discontinuities, and maintains a compact form factor. Each impedance section can be designed to contribute to specific transmission zeros, allowing multiple zeros to be achieved within a single unified structure rather than adding separate resonant cavities for each zero.
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 enables efficient filtering with reduced construction time and cost, maintaining performance across a wide frequency range with high attenuation, and is less sensitive to manufacturing inaccuracies, making it suitable for high-frequency applications like telecommunications and Earth observation.
Implementation Method 1
A novel band-pass filter design utilizing commensurate-line structures (CLS) and stub-modified commensurate-line structures (SMCLS) to provide multiple transmission zeros
Implementation Method 2
waveguide band-pass filters (BPFs) to remove unwanted spurious signals
Data Source
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AI summary
The present invention relates to a waveguide band-pass filter. There is provided a filter for filtering wavelengths of an electromagnetic signal to provide a filtered signal, the filter comprising: at least one commensurate-line structure (CLS); and, at least one stub-modified commensurate-line structure (SMCLS) arranged to provide a corresponding at least one transmission zero in the filtered signal.