Built-in Cross-Coupled Dielectric Filter for Microwave Stability
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Solution Overview
Problem
Separate dielectric filters face issues with reliability due to external dielectric coupling, are prone to damage during handling and installation, suffer from temperature-induced performance deterioration, and struggle with high-frequency electromagnetic interference, making it difficult to produce high-quality filters.
Innovation Solution
A built-in cross-coupled dielectric filter design featuring sequentially welded coaxial dielectric resonators with mutually coupled capacitors or inductors etched on their surfaces, and input/output ports coated with polytetrafluoroethylene, achieving stable temperature-independent performance and improved amplitude-frequency characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If external dielectric coupling is adopted in separate dielectric filters, then the filter structure is simple to manufacture, but the reliability deteriorates due to poor contact and easy detachment of capacitors and terminals
Solution Approach 1:
The patent merges the capacitor and inductor components directly into the dielectric resonator body through etching, eliminating separate external coupling components. This integration ensures that the coupling structures become an intrinsic part of the resonator, preventing detachment and improving reliability while maintaining manufacturing simplicity through direct etching processes.
Solution Approach 2:
The coupling capacitors and inductors are nested within the dielectric resonator body itself, with etched grooves forming these components inside the resonator structure. This nesting approach allows the coupling elements to be embedded within the main body, ensuring stable mechanical contact while maintaining a compact and simple overall structure.
2Manufacturing precision
If the number of levels in ceramic-substrated capacitors is increased, then the filtering performance is improved, but the capacitors become longer and more prone to rupture during handling and installation
Solution Approach 1:
Instead of increasing the length of capacitors by adding more levels in the vertical direction, the patent transitions to a planar etching approach where coupling structures are created on the lateral surfaces of the dielectric resonator. This dimensional shift from vertical stacking to lateral etching maintains filtering performance while significantly improving mechanical strength and resistance to handling damage.
Solution Approach 2:
The patent segments the coupling structures into separate etched regions on the dielectric resonator surface, with distinct areas for capacitors and inductors. This segmentation allows for optimized local designs that maintain electrical performance while avoiding the need for long, fragile multi-level capacitor structures, thereby improving overall mechanical robustness.
3Ease of manufacture
If ceramic substrate is used as capacitor substrate, then the manufacturing process is simplified, but temperature drift causes performance deterioration at high and low temperatures
Solution Approach 1:
The patent changes the material parameter selection by using dielectric resonators with temperature-stable properties and etching coupling structures directly into them. This parameter change in material selection and structural design allows the filter to maintain stable performance across temperature ranges while keeping the manufacturing process simple through direct etching methods.
Solution Approach 2:
The patent employs composite construction where the dielectric resonator body combines mechanical strength with temperature stability, and the etched coupling structures integrate electrical functionality with thermal stability. This composite approach maintains manufacturing simplicity while achieving temperature-independent performance through the inherent properties of the dielectric material and its etched features.
4Ease of manufacture
If exterior dielectric coupling is used at high frequencies above 3G, then the coupling mechanism is simple to implement, but electromagnetic field interference between levels becomes very strong and difficult to control
Solution Approach 1:
The patent extracts the coupling functions from external separate components and integrates them directly into the dielectric resonator body through etching. This extraction and integration approach simplifies the overall structure while providing better control over electromagnetic field distribution, reducing unwanted interference between coupling levels at high frequencies above 3G.
Solution Approach 2:
The patent applies local quality by creating specific etched patterns in different regions of the dielectric resonator surface - with distinct capacitor regions and inductor regions designed for optimal electromagnetic performance. This localized design approach allows control over field distribution and minimizes interference between different coupling elements while maintaining implementation simplicity.
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 enhances filter reliability and stability across temperature extremes and significantly improves the rectangular degree and amplitude-frequency characteristics, addressing the limitations of separate dielectric filters.
Implementation Method 1
The mutually coupled capacitors are made by etching mutually-matched open-loop grooves on the two adjacent lateral surfaces of the adjacent coaxial dielectric resonators
Implementation Method 2
The mutually coupled inductors are made by etching mutually-matched straight-line grooves on the two adjacent lateral surfaces of the adjacent coaxial dielectric resonators
Implementation Method 3
The input and output ports are coated with the polytetrafluoroethylene material
Data Source
AI summary
A stable and reliable built-in cross-coupled dielectric filter with temperature-independent performances and improved rectangular degree and amplitude-frequency characteristic is disclosed. The built-in cross-coupled dielectric filter comprises at least three sequentially welded coaxial dielectric resonators. Mutually coupled capacitors or mutually coupled inductors are etched on the two adjacent lateral surfaces of the adjacent coaxial dielectric resonators, respectively, with an alternate setup. The input and output ports of the built-in cross-coupled dielectric filter are positioned at the two coaxial dielectric resonators at the head and tail, respectively. The present invention is particularly applicable to the high-frequency realm such as microwave.