RF Filter Resonator Securing via Elastic Gasket
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Solution Overview
Problem
Existing RF filters face challenges in securing dielectric resonators stably due to thermal expansion differences between resonator materials and housings, leading to potential contact issues and performance changes, especially in smaller, lower-frequency applications.
Innovation Solution
The RF filter design incorporates metallic washers with protrusions and a pressing member with an elastic member to securely fasten the dielectric resonator within a cavity, using a combination of soldering and adjustable tuning bolts to ensure stable contact and improved performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a dielectric resonator is used to reduce filter size, then the filter size is reduced, but thermal expansion differences cause the resonator to become unsecure or provide inadequate contact
Solution Approach 1:
An elastic gasket is introduced as an intermediary component between the dielectric resonator and the housing. This gasket compensates for thermal expansion differences by deforming elastically, maintaining secure contact between the resonator and housing across temperature variations, thus resolving the reliability issue while preserving the compact filter design.
Solution Approach 2:
The patent utilizes the elastic properties of the gasket material to change its physical parameters (deformation) in response to temperature changes. This allows the gasket to adapt its shape and maintain constant contact pressure on the resonator, compensating for thermal expansion mismatches without requiring larger tolerances or additional fastening mechanisms.
2Adaptability or versatility
If a dielectric disk is added to a coaxial resonator to enable smaller filters at lower frequencies, then the frequency range is extended, but thermal expansion differences still cause inadequate securing
Solution Approach 1:
The elastic gasket serves as a mediator between the modified resonator structure (with dielectric disk) and the housing. It absorbs thermal expansion differences, ensuring that the resonator remains securely positioned and maintains adequate contact with the housing across the extended frequency range, particularly important for lower frequency applications where the resonator structure is more complex.
3Reliability
If conventional fastening methods are used, then the resonator can be secured, but PIMD performance deteriorates due to inadequate contact stability
Solution Approach 1:
The elastic gasket acts as a mediator that provides continuous, stable contact between the resonator and housing without requiring rigid fastening methods. This stable contact prevents micro-movements and poor connections that generate passive intermodulation distortion, thereby improving PIMD performance while maintaining secure resonator positioning.
Solution Approach 2:
The gasket's elastic deformation capability allows it to maintain optimal contact pressure on the resonator across temperature variations. This consistent contact pressure ensures stable electrical connections and prevents the contact instability that leads to PIMD, without requiring additional fastening hardware that could introduce new sources of distortion.
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 design effectively secures the resonator, enhancing PIMD performance by maintaining stable contact and reducing thermal expansion-related issues, thus improving the filter's operational stability and frequency tuning capabilities.
Implementation Method 1
The pressing member may include an elastic member capable of applying an elastic force
Implementation Method 2
because of a difference in thermal expansion coefficients between the dielectric resonator element and the housing, thermal contraction and expansion due to temperature changes can result in the dielectric resonator elements becoming unsecure or providing inadequate contact
Data Source
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AI summary
An RF filter for improving PIMD performance includes: a housing having at least one cavity and a dielectric resonator (104) held in the cavity; washers (350) shaped as circular plates and made of metal that are joined to an upper and lower portion of the dielectric resonator; and a cover joined to the housing. A protrusion (355) is formed on one side of the washer to contact the cover or the housing, where the washer protrusion may increase in height along a direction moving away from the center. In another embodiment, the resonator is a metallic coaxial resonator (604), provided with a dielectric disk (800) on top of the coaxial resonator. A washer (850) with a protrusion (855) is joined to an upper portion of the dielectric disk.