Suspended Resonator Cavity Filter for Wider Bandwidth
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Solution Overview
Problem
Existing filters face challenges in achieving wider bandwidth and reduced volume due to structural limitations, high production costs, and complexity, especially with increasing operating frequencies, and are hindered by harmonic interference from flying rods.
Innovation Solution
A multi-mode cavity filter using a metal cavity with suspended resonators that generate multiple resonant frequencies, including a first resonator and a second resonator with resonance plates, allowing for adjustable null points and omitting a coupling structure of a flying rod, thereby reducing volume and harmonics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of stationary object
If a multi-mode dielectric resonator is used to reduce filter volume, then the volume is reduced and loss is prevented, but the design difficulty increases and production/assembly complexity increases leading to high costs
Solution Approach 1:
The filter is divided into multiple independent cavity units, each containing simplified resonator structures. This segmentation allows each cavity to be designed and assembled separately, reducing overall design complexity while maintaining the multi-mode resonance functionality needed for compact size.
Solution Approach 2:
The patent employs standardized, easily manufacturable cavity structures with simple resonator elements that can be produced through conventional manufacturing processes. This approach prioritizes ease of mass production over optimized complex designs, reducing both design complexity and manufacturing costs.
2Speed
If the operating frequency of the filter is increased to achieve higher performance, then the bandwidth is expected to widen, but the structural limitations of cavity and dielectric waveguide filters prevent meeting the bandwidth requirement
Solution Approach 1:
The patent introduces adjustable coupling structures between cavities that can be tuned during assembly or operation. This dynamic adjustability allows the filter to adapt its bandwidth characteristics to meet requirements at different operating frequencies, overcoming the fixed structural limitations of traditional cavity filters.
Solution Approach 2:
The filter design incorporates variable geometric parameters in the cavity structures and coupling elements that can be modified to change the operating frequency and bandwidth characteristics. This allows the same basic structure to be adapted for different frequency ranges and bandwidth requirements.
3Ease of operation
If a flying rod coupling structure is used in high frequency filters, then coupling between resonators is achieved, but harmonic generation occurs that creates greater inhibition impact on the near-end of the passband
Solution Approach 1:
The patent removes the traditional flying rod coupling structure entirely and replaces it with direct cavity-to-cavity coupling through shared walls or proximity coupling. This extraction of the harmful element eliminates the source of harmonic generation while maintaining the necessary coupling functionality between resonators.
Solution Approach 2:
The patent transforms the coupling mechanism to use the cavity walls themselves as the coupling medium, converting what would be a source of harmonics (discrete coupling elements) into a distributed coupling structure that naturally suppresses harmonic generation while maintaining passband performance.
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 filter achieves compact design, adjustable bandwidth, and reduced harmonic interference by utilizing a metal cavity with suspended resonators, enabling efficient filtering performance and ease of assembly.
Implementation Method 1
a first resonator configured to generate a first resonant frequency; and a second resonator electrically connected to the first resonator and configured to generate a second resonant frequency
Data Source
AI summary
A multi-mode cavity filter includes: a metal cavity formed into a hollow shape; and a plurality of resonators supported in suspension within the metal cavity and not contacting with an inner wall of the metal cavity. The plurality of resonators includes: a first resonator configured to generate a first resonant frequency; and a second resonator electrically connected to the first resonator and configured to generate a second resonant frequency. The second resonator includes a plurality of resonance plates. A first number of the second resonant frequency is associated with a second number of the plurality of resonance plates.