Dielectric Multi-Mode Resonator With Air Gaps
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Solution Overview
Problem
Existing radio-frequency filters using dielectric multi-mode resonators face challenges in achieving compact size, low insertion loss, and tunable frequency due to difficulties in creating reliable ceramic-metal joints and supporting a wide frequency band without spurious responses.
Innovation Solution
A dielectric multi-mode resonator design featuring a metal housing with a ceramic body having orthogonal axes and asymmetric cuts or holes, supported by a low-permittivity material, allowing for adjustable coupling and frequency tuning through screws, and incorporating air gaps to manage temperature expansion and dimension tolerances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If ground contact or full metal plating is used around ceramic resonators, then compact size and structural support are achieved, but manufacturing difficulty increases due to different coefficient of linear temperature expansion between ceramic and metal
Solution Approach 1:
A metal housing acts as an intermediary structure that provides mechanical support and grounding without requiring direct ceramic-metal joints. The housing contains the ceramic resonator body and provides the necessary structural framework, eliminating the need for difficult ceramic-to-metal plating connections while maintaining compact form factor.
2Strength
If full metal plating is applied on ceramic block, then structural integrity and electrical connection are improved, but adaptability decreases making it difficult to connect to other mechanics and achieve tunable couplings
Solution Approach 1:
The resonator system is segmented into separate functional components: a metal housing providing structural integrity and grounding, and a ceramic resonator body providing resonant functionality. This segmentation allows independent optimization of each component and enables flexible coupling mechanisms through the housing structure rather than through plated ceramic surfaces.
Solution Approach 2:
Tuning screws are introduced as dynamic adjustment elements that can modify the coupling between resonators and the housing. These screws allow the electrical characteristics to be adjusted after assembly, providing adaptability and tunable coupling capabilities that would be impossible with fixed plated ceramic structures.
3Ease of manufacture
If orthogonal TM dual mode/multimode resonators without straight cavity contact are used, then ease of assembly is improved, but frequency band width and spurious response performance are insufficient
Solution Approach 1:
The metal housing serves multiple functions simultaneously: it provides structural support, acts as a ground reference, enables coupling between resonators, and allows for frequency tuning. This multi-functional design achieves ease of assembly without compromising frequency band width or spurious response performance, as the housing structure is specifically designed to support orthogonal TM modes while maintaining proper electromagnetic coupling.
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 enables high Q-factor, miniaturized filters with improved power handling and frequency range, maintaining low electric fields and compensating for temperature-induced frequency drift, while allowing for efficient coupling with single-mode resonators and cost-effective manufacturing.
Implementation Method 1
a resonator body made of a dielectric material... a dielectric body having a first thickness between the top and bottom surfaces of the cavity
Implementation Method 2
The resonator comprises a metal housing. The housing has a top surface, a bottom surface and four sides
Implementation Method 3
A joint between ceramic and metal is difficult to create because of different coefficient of linear temperature expansion
Data Source
Figure 1~2A
Figure 2B~3
Figure 4~5
AI summary
A radio-frequency filter with at least one dielectric multi-mode resonator is provided. The resonator comprises a metal housing (102) with a top surface (104), a bottom surface (106), four sectors (108A, 108B, 108C, 108D) between the top and bottom surfaces, and comprising a resonator cavity therein. The resonator further comprises a dielectric body (110) positioned inside the cavity, the dielectric body having a first thickness between the top and bottom surfaces of the cavity, wherein there is a gap (302A, 302B, 302C, 302D) between the sectors of the housing and the dielectric body, the dielectric body comprising a hollow (112A, 112B) on the surface facing the top surface of the housing and on the surface facing the bottom surface of the housing, the dielectric body thus having a second thickness at the location of the hollows, the second thickness being smaller than the first thickness.