Concave Triple-Mode Cavity Resonator for Compact High-Q Filters
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Solution Overview
Problem
Existing single-mode dielectric filters face challenges of high manufacturing cost and large volume, while TM triple-mode filters with a silver-coated dielectric resonant block suffer from low conductivity and limited use due to low Q values, and concave triple-mode cavity structures have issues with limited tuning range, sensitivity to resonant frequency, and high processing costs.
Innovation Solution
A concave triple-mode cavity resonant structure with a dielectric resonant block and support frame, where the dielectric constant of the support frame is lower than the block, allowing for a ratio of cavity to block side lengths between 1.0 and 1.30, enabling Q value transitions and frequency tuning through coupling structures and tuning devices, reducing overall insertion loss and volume.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of stationary object
If a single-mode dielectric filter is used to replace traditional metallic cavity filters, then the manufacturing cost and volume are reduced, but the Q value is insufficient and performance is limited
Solution Approach 1:
The patent combines multiple resonant modes (TE101, TM210, TM111) within a single dielectric resonator body to achieve triple-mode resonance. This merging of multiple resonant functionalities into one component enables the filter to achieve high Q value performance while maintaining compact volume, resolving the contradiction between volume reduction and performance maintenance
Solution Approach 2:
The patent employs a dielectric resonator with specific material properties (dielectric constant εr=35, Q×f=48000MHz) and combines it with a metallic cavity structure. This composite approach leverages the high Q value characteristics of dielectric materials while using the metallic cavity to establish well-defined resonant modes, achieving both volume reduction and high performance
2Volume of stationary object
If a TM triple-mode filter with silver-coated dielectric resonant block is used, then the volume is reduced, but the conductivity is degraded and Q value is low
Solution Approach 1:
The patent extracts the silver coating layer from the dielectric resonator surface, eliminating the source of conductivity degradation. By removing the silver layer that forms insulating vitreous substance after baking, the design avoids the Q value reduction problem while maintaining the compact volume benefits of dielectric resonators
Solution Approach 2:
The patent replaces the expensive and performance-degrading silver coating with a simpler dielectric material surface. This substitution uses a more stable and manufacturable approach that avoids the complexity and performance issues associated with silver baking processes while maintaining electrical performance
3Reliability
If the ratio of cavity size to dielectric resonant block size is increased to improve base mode Q value, then the base mode Q value increases, but the higher-order mode Q value decreases and filter volume increases
Solution Approach 1:
The patent optimizes the ratio of cavity side length to dielectric resonator side length within the specific range of 1.01-1.30. This parameter optimization simultaneously achieves high base mode Q value (greater than 800) and maintains compact cavity volume, while also ensuring the higher-order mode Q value remains above 400, resolving the trade-off between different mode Q values and volume
4Volume of stationary object
If a concave triple-mode cavity structure is used to reduce volume, then the volume is reduced, but the tuning range is limited and processing cost increases
Solution Approach 1:
The patent incorporates adjustable coupling structures between resonant cavities that enable dynamic tuning of the filter characteristics. The coupling coefficients between cavities can be adjusted to achieve the desired passband width and frequency response, providing operational flexibility while maintaining the reduced volume benefits of the compact cavity design
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 structure achieves a high Q value with reduced volume and insertion loss, facilitating efficient frequency tuning and cost-effective production, with a 40% reduction in volume and 30% reduction in insertion loss compared to prior designs.
Implementation Method 1
the dielectric resonant block and the dielectric support frame form a triple-mode dielectric resonator
Implementation Method 2
the triple-mode dielectric resonant structure is internally provided with a coupling structure for changing orthogonal properties of a degenerate triple-mode electromagnetic field in the cavity
Data Source
Figure 1~2
Figure 3~5
AI summary
The disclosure discloses a concave triple-mode cavity resonance structure and a filter with the resonance structure. The structure comprises a cavity and a cover plate, wherein the cavity is internally provided with a dielectric resonance block and a dielectric support frame; at least one end face of the cavity and/or the dielectric response block is concave; the dielectric resonance block and the dielectric support frame form a triple-mode dielectric resonance rod; one end or any end of the cube-like dielectric resonance block is connected with the dielectric support frame; the dielectric support frame is connected with an inner wall of the cavity; and the dielectric response block and the dielectric support frame form triple-mode resonance in three directions along the X, Y and Z axes of the cavity. The cavity multi-mode filter disclosed by the disclosure ensures a high Q value when the resonance rod and the cavity are at a small distance apart, while also increasing the turning range of a tuning screw, and reducing sensitivity to resonance frequencies due to the small distance between the cavity and the dielectric resonance block, thereby facilitating production debugging and reducing production cost.